Komunikacijaski sistemi

Navigacijski sistemi

Radio signali

Radio-talasi su vrsta elektromagnetskog zračenja u opsegu EM spektra po talasnoj dužini iznad infracrvenog spektra. Područje radijskog spektra obuhvata talasne dužine od milimetar do kilometar odnosno frekvencije od 3 Hz do 300 GHz (gigaherca;1 GHz = 1×109 Hz).

Radio-talasi nastaju u antenama kada visokofrekventna struja izaziva naizmeničnu promijenu električnog i magnetskog polja u okolini antene što predstavlja radio zračenje. Talasna dužina zavisi od rezonantne frekvencije oscilatornog kola koje se nalazi u izlaznom stepenu i koje je povezano sa antenom. Veličina i tip antene utiču na efikasnost zračenja talasa i to tako da je nejefikasnije zračenje u slučaju da je veličina antene jednaka četvrtini talasne dužine. Veća antena - veće su talasne dužine (manja frekvencija) i obrnuto.

Radio signali Prost radio-talas je sinusna talasna pojava i kao takav ne nosi mnoge informacije. Da bi se neka informacija prenijela, potrebno je nekako „utisnuti“ u talas ali i potom prepoznati na prijemnoj strani. Taj postupak se zove modulacija i on predstavlja mijnjanje neke od osobina talasa u sinhronizmu sa signalom koji predstavlja informaciju. U zavisnosti koja se osobina mijnja postoji:

amplitudska modulacija,frekventna modulacija ifazna modulacija.

Na prijemnoj strani postoji prijemna antena koja je vezana za prijemno oscilatorno kolo koje rezonuje na željenoj frekvenciji. Kada se elektromagnetska energija talasa pretvori u visokofrekventnu struju u oscilatornom kolu, tada se pristupa demodulaciji i pojačavanju signala. Takav se signal može dovesti na zvučnik i onda, recimo, čuti signal neke radio-stanice.

Radio signali

Kretanje signala

Radio frekventni opseg

Lokacija antena na zrakoplovu

Radio signali

zrakoplovstvo

Princip modulacijeAmplituna modulacija

Kretanje signala

Zračni prostor

• Zračni prostor je dio atmosfere iznad kopna i teritorijalnog mora koji kontrolira pojedina država.

• Kontrolirani zračni prostor u kojem se odvija promet zrakoplova kontroliran od strane kontrole leta.

• Nekontrolirani zračni prostor u kojem kontrola leta ne vrši kontrolu i nema utjecaj, ali može davati savjete.

• Zračni prostor može biti unaprijed podijeljen u razne zone uključujući i one u kojima postoje ograničenja letenja ili potpune zabrane leta.

• Prema odluci od 12. marta 1990. godine koju je donijela Organizacija međunarodnog civilnog zrakoplovstva (ICAO) zračni prostor podijeljen je na klase od A-G:

Zračni prostor

– Klasa A je zračni prostor na velikim visinama (iznad 6000 m nadmorske visine). U nekim zemljama u taj prostor je uključena i zona oko velikih aerodroma. U prostoru se leti isključivo po IFR pravilima, poštujući uputstva kontrole leta. Ograničenja brzine nema (osim zabrane probijanja zvučnog zida nad kopnom).

– Klasa B uključuje zonu između 4000 i 6000 m u koji je također uključen zračni prostor oko aerodroma. Ulaz u ovu zonu mora odobriti kontrola leta, zrakoplov mora imati ugrađen uređaj (transporder) koji automatski šalje podatke o visini i smjeru leta. U ovom području dozvoljeno je i VFR letenje. Svi zrakoplovi moraju poštivati upute kontrole leta.

– Klasa C je zona oko aerodroma na kojoj se odvija srednje gusti promet. Kontrola leta kontrolira zrakoplove koji lete po IFR pravilima (po potrebi i ona koja lete po VFR pravilima) te im daje i sigurnosne upute i zahtjeve. Za ulazak u ovu zonu nije potrebna dozvola kontrole leta nego samo najava ulaska.

Zračni prostor

– Klasa D se odnosi uglavnom na zonu uzlijetanja i slijetanja zrakoplova i obuhvaća zonu od oko 10 km oko aerodroma. U ovoj je zoni dozvoljeno letenje po IFR a po VFR pravilima kada je dobra vidljivost. Svi zrakoplovi moraju poštivati naloge kontrole leta.

– Klasa E je zona u kojoj upute Kontrole leta moraju poštivati zrakoplovi koji lete po IFR pravilima.

– Klasa F je nekontrolirani zračni prostor. U njemu se može letjeti po IFR pravilima ali to nije preporučljivo radi mogućih "bliskih susreta" sa zrakoplovima koji lete po VFR. U ovoj zoni nije neophodna komunikacija s Kontrolom leta.

– Klasa G je također nekontrolirana zona u kojoj Kontrola leta ne daje nikakva uputstva niti preporuke.

Zračni prostor

NAVIGATION

– Relative Bearing• Direction you want to

track to the station. Shown by the indicator needle on the ADF.

– Magnetic Heading • Direction your nose is

pointed.

– Magnetic Bearing• Direction flown to the

station in still air. RB + MH (=/- 180 for FROM)

Zračni prostor • A service to promote the safe, orderly, and expeditious flow of air

traffic. Safety is principally a matter of preventing collisions with other aircraft, obstructions, and the ground; assisting aircraft in avoiding hazardous weather; assuring that aircraft do not operate in airspace where operations are prohibited; and assisting aircraft in distress. Orderly and expeditious flow assures the efficiency of aircraft operations along the routes selected by the operator. It is provided through the equitable allocation of system resources to individual flights.

Air-traffic control (ATC) is the product of the National Airspace System (NAS), comprising airspace; air navigation facilities and equipment; airports and landing areas; aeronautical charts, information, and publications; rules, regulations, and procedures; technical information; and personnel.

Zračni prostor • Flight rules

• Two principal categories of rules governing air traffic are visual flight rules (VFR) and instrument flight rules (IFR). Visual flight rules govern the procedures for conducting flight where the visibility, the ceiling, and the aircraft distance from clouds are equal to or greater than established minima. Ceiling is the height above the Earth's surface of the lowest layer of clouds or obscuring phenomenon that significantly restricts visibility. The minima for operation under visual flight rules vary by airspace. In controlled airspace, the ceiling must be at least 1000 ft (305 m) and the visibility must be at least 3 statute miles (4830 m). The aircraft must remain clear of clouds, at least 500 ft (150 m) below, 1000 ft (305 m) above, and 2000 ft (610 m) horizontally. Instrument flight rules go into effect when visibility, distance from clouds, and ceiling conditions are less than the minima specified for visual flight rules. To operate under these rules, the pilot must pass an instrument flight examination and have an adequately instrumented aircraft.

• Aircraft operating under visual flight rules (VFR aircraft) maintain separation from other aircraft visually. IFR aircraft in controlled airspace operate in accordance with clearances and instructions provided by air-traffic controllers for the purpose of maintaining separation and expediting the flow of traffic. Flight crews operating under instrument flight rules are responsible for seeing and avoiding other aircraft, but the air-traffic control clearances they receive provide substantial added assurance of safe separation. Consequently, flight crews often will operate under instrument flight rules even though the weather satisfies visual meteorological conditions.

Flight Rules

• Visual Flight Rules (VFR)– Flight with reference to the ground

• Instrument Flight Rules (IFR)– Flight with reference to the aircraft’s

instruments

Day VFR Requirements

• Airspeed Indicator (ASI)

• Altimeter (ALT)

• Compass

• Working Timepiece

Day and Night

• Day– Period of time when center of sun’s disc is less than

6° below horizon– Period starting one half hour before sunrise and

ending one half hour after sunset

• Night– Period of time when center of sun’s disc is more than

6° below horizon– Period starting one half hour after sunset and ending

one half hour before sunrise

Night VFR Requirements

• Airspeed Indicator (ASI)• Sensitive Pressure Altimeter (ALT)• Compass• Turn and Bank Indicator• Gyro Magnetic Compass or Heading Indicator• Means to Illuminate Flight Instruments• Each crewmember must have access to working

timepiece and flashlight

Aircraft Lighting• Right wing

– Green light– Visible 110° for 2 miles

• Left wing– Red light– Visible 110° for 2 miles

• Tail– White light– Visible 140° for 2 miles

• Anti-Collision Light (AKA Beacon)– White or red light– Visible 360°

Aircraft Lighting

ATC Clearance and Instruction• Clearance

– Authorization from ATC for aircraft to proceed within controlled airspace under specific conditions

– Pilot must ask for clarification if unsure of any meaning of any part of an ATC clearance

– Once you accept it, you are required to comply with an ATC clearance– If you are VFR, you must read back the text of the clearance only if

requested by ATC to do so– If clearance unacceptable, pilot should contact ATC with intentions

• Instruction– Directive issued by ATC for air traffic control purposes– You are required to comply with and acknowledge receipt of an ATC

instruction which is directed to you provided the safety of the aircraft is not jeopardized

Flight Plans

• VFR Flight Plans– Required if going beyond 25NM from departure aerodrome– Purpose is to inform people where you are going and when you

will get there– Should be filed with ATC or FIC (Flight Information Centre)– Must be closed within 1 hour after landing

• VFR Flight Itinerary– May be used instead of a flight plan– Purpose is to inform people where you are going and when you

will get there– Should be filed with a responsible person– Must be closed within 24 hours after landing

Cruising Altitudes

• Aircraft must fly at proper cruising altitudes

• Below 18,000 ft, altitudes in thousands

• Above 18,000 ft, altitudes in flight levels

• Altitudes measured from Mean Sea Level (MSL)

• VFR Cruising Altitudes begin at 3,000 ft Above Ground Level (AGL)

Cruising Altitudes

• Track of180° - 359°

– VFREven thousands plus 500 ft ASL

– IFREven thousands

• Track of000° - 179°

– VFROdd thousands plus 500 ft ASL

– IFROdd thousands

VFR Weather Limits

Airspace Flight Visibility Distance from Cloud

Controlled 3 SM Horizontally 1 SM

Vertically 500 ft

Uncontrolled above 1000 ft AGL

1 SM (day)

3 SM (night)

Horizontally 2000 ft

Vertically 500 ft

Uncontrolled below 1000 ft AGL

2 SM (day)

3 SM (night)

Clear of Cloud

Special VFR Limits

• Special VFR may be requested by pilot if weather falls below VFR standards in a control zone

Visibility Distance from Cloud

Aircraft other than Helicopters

1 SM Clear of Cloud

Helicopters ½ SM Clear of Cloud

Oxygen Requirements

• Below 10,000 ft– Oxygen supply not required

• Between 10,000 ft and 13,000 ft– Oxygen supply required if flying more than 30 minutes at this

altitude

• Above 13,000 ft– Oxygen supply required

• Hypoxia– Dangerous condition where pilot does not get enough oxygen– Creates sense of euphoria (false sense of “well being”)

Wake Turbulence

• Wake Turbulence is large, rotating, unstable air left behind an aircraft

• Worse with large, slow aircraft (created by high angle of attacks), and prominent on take-off and landing

• Can last up to 5 minutes; Aircraft must wait at least 2 minutes before taking-off/landing behind large aircraft

• Small aircraft should take-off before or land after rotation/landing point of large aircraft ahead

Airline codes

• IATA airline designator

IATA airline designators, sometimes called IATA reservation codes, are two-character codes assigned by the International Air Transport Association (IATA) to the world's airlines in accordance with the provisions of IATA Resolution 762. They form the first two characters of the flight number.

Designators are used to identify an airline for all commercial purposes, including reservations, timetables, tickets, tariffs, air waybills, and in airline interline telecommunications.

There are three types of designator: unique, alpha/numeric, and controlled duplicate.

IATA maintains two policies to deal with the limited number of available codes:

after an airline is delisted, the code becomes available for reuse after six months;

IATA issues "controlled duplicates".

Controlled duplicates are issued to regional airlines whose destinations are not likely to overlap, in such a way that the same code would be shared by two different airlines. The controlled duplicate is denoted here with an asterisk (*) following the code and in IATA literature as well.

Airline codes

• ICAO airline designator

The ICAO airline designator is a code assigned by the International Civil Aviation

Organization to aircraft operating agencies, aeronautical authorities, and services. The codes are unique by airline which is not true for the IATA airline designator codes.

Each aircraft operating agency, aeronautical authority, and services related to international aviation is allocated both a three-letter designator and a telephony designator. The designators are listed in ICAO Document 8585: Designators for Aircraft Operating Agencies, Aeronautical Authorities and Services.

An example is:

Three-letter designator – AAL

Telephony designator – AMERICAN

Operator – American Airlines

Certain combinations of letters are not allocated to avoid confusion with other systems (for example SOS). Other designators (particularly those starting with Y and Z) are reserved for government organizations.

Designator YYY is used for operators that do not have a code allocated

Airline codes

• Call sign

Most airlines employ a distinctive and internationally recognized call sign that is normally spoken during airband radio transmissions as a prefix to the flight number. The flight number is normally then published in their public timetable and appears on the arrivals and departure screens in the airport terminals served by that particular flight. In cases of emergency, the airline name and flight number, rather than the individual aircraft's registration, are normally mentioned by the main news media.

Some call signs are less obviously associated with a particular airline than others. This might be for historic reasons, or possibly to avoid confusion with a call sign used by an established airline.

Not all of these operators of aircraft are civilian and some only operate ad hoc chartered flights rather than scheduled flights; some operate both types of flights. Some cargo airlines specialize in freight transport, an emphasis that may be reflected in the company's name.

Clearly companies' names will change over time, normally due to bankruptcies or mergers occurring. Country names can also change over time and new call signs may be agreed in substitution for traditional ones. The country shown alongside an airline's call sign is that wherein most of its aircraft are believed to be registered, which may not always be the same as the country in which the firm is officially incorporated or registered. There are many other airlines in business whose radio call signs are more obviously derived from the trading name.

The callsign should normally resemble the operators name or function and not be confused with callsigns used by other operators. The callsign should be easily and phonetically pronounceable in at least English, French, Spanish or Russian.

Airline codes

A flight number, when combined with the name of the airline and the date, identifies a particular flight. This callsign should not be confused with the tail number of the aircraft, although both can be used as a call-sign as used in general aviation. A particular aircraft may fly several different flights in one day, and different aircraft may be used for the same flight number on successive days.

A number of conventions have been developed for defining flight numbers, although these vary widely from airline to airline. Eastbound and northbound flights are traditionally assigned even numbers, while westbound and southbound flights have odd numbers. Other airlines will use an odd number for an outbound flight and use the next even number for the reverse inbound flight. For destinations served by multiple flights per day, numbers tend to increase during the day. Hence, a flight from point A to point B might be flight 101 and the return flight from B to A would be 102, while the next pair of flights on the same route would usually be assigned codes 103 and 104.

Flight numbers of less than three digits are often assigned to long-haul or otherwise premium flights. Flight number 1 is often used for an airline's "flagship" service. For example, British Airways flight 1 was the early morning supersonic Concorde service from London to New York City; Air New Zealand flight 1 is the daily service from London to Auckland via Los Angeles; and El-Al flight 1 is the daily overnight service from Tel Aviv to New York City. Four-digit numbers in the range 1000-4999 typically represent regional affiliate flights, while numbers larger than 5000 are generally codeshare numbers for flights operated by entirely different airlines or even railways.

Airline codes

Likewise, flight numbers larger than 9000 are usually referred to ferry flights, that carry no passengers and are only to move an aircraft from point A to point B, where it is supposed to start a new commercial flight. Flight numbers starting with 8 are often used for charter flights, but it always depends on the commercial carrier choice.

Flight numbers are often taken out of use after a crash or a serious incident. For example, following the crash of Alaska Airlines Flight 261, the airline changed the flight number for subsequent flights following the same route to 295. Also, American Airlines Flight 77, which regularly flew from Dulles International Airport in Washington, DC, to Los Angeles International Airport, was changed to Flight 149 after the September 11, 2001 attacks.

Note that, although 'flight number' is the term used colloquially, the official term as defined in the Standard Schedules Information Manual (SSIM) published annually by the International Air Transport Association (IATA) Schedules Information Standards Committee (SISC), is flight code. Officially the term 'flight number' refers to the numeric part (up to four digits) of a flight code. For example, in the flight codes BA2490 and BA2491A, "2490" and "2491" are flight numbers. Even within the airline and airport industry it is common to use the colloquial term rather than the official term.

Flight numbers are also sometimes used for spacecraft, though a flight number for an expendable rocket (say, Ariane 5 Flight 501) might more reasonably be called the serial number of the vehicle used, since an expendable rocket can only be launched once. Space Shuttle launches get numbers with the prefix STS, for example, STS-93.

Airline codes

JA BON B&H Airlines Air Bosna Bosnia and Herzegovina

TK THY Turkish Airlines TURKISH Turkey

LH DLH Lufthansa LUFTHANSA Germany

IATA ICAO AIRLINECALLSIGN

COUNTRY

Introduction

• What is TCAS?

• Big picture, How it works

• TCAS - Philosophy

• TCAS/- Future?

Introduction

• What is TCAS?

• Big picture, How it works

• TCAS - Philosophy

• TCAS/- Future?

What is TCAS?

• Traffic Collision Avoidance System

• Situational awareness tool– Shows other air traffic in the vicinity

• Collision avoidance– Gives avoidance steering cues to pilots

How it works

• IFF interrogator

• Mode A, C and S

• Components;– Computer– Mode S transponder– Antenna assembly– ATC/TCAS control panel– Traffic advisory indicator

How it works

• A transponder is a receiver / transmitter device designed to transmit a response signal when legitimately interrogated. [NATO definition]

• An automatic device that transmits a predetermined message in response to a predefined received signal. [Wikipedia]

• A ground-based primary surveillance radar (PSR) detects the presence of an aircraft and indicates its bearing and distance.

• At the same time a secondary surveillance radar (SSR), synchronized (on boresight) with the PSR, interrogates the aircraft using a series of pulses.

• The aircraft transponder responds with a different series of pulses containing situational information, typically its aircraft identifier and altitude.

• The information from the PSR and SSR is then integrated and presented on the ATC console.

How it works

How it works

• This system is also known as identification friend or foe / secondary surveillance radar (IFF/SSR)

• The onboard aircraft equipment consists of:– an ATC transponder control unit for setting the modes of operation and the

control codes,– a dedicated ATC transponder, and– antennas.

• Mode A (simple system):– Aircraft identification (Call-sign)

• Mode C (more advanced):– Mode A + altitude

• Mode S (more recently):– Mode C + 24 bit address identifier (unambiguous)– Provides limited air-air and air-ground communications– Can also provides whereabouts of other aircraft in its vicinity – Uses digital error-correcting codes for improved reliability

How it works • A transponder (short-for Transmitter-responder) and sometimes abbreviated to XPDR,

XPNDR, TPDR or TP is an electronic device that produces a response when it receives a radio-frequency interrogation. In aviation, aircraft have transponders to assist in identifying them on radar and on other aircraft's collision avoidance systems.

• Air traffic control units use the term "squawk" when they are assigning an aircraft a transponder code, e.g. "Squawk 7421". Squawk or squawking thus can be said to mean "select transponder code" or "I have selected transponder code xxxx".

How it works • Secondary surveillance radar (SSR) is a radar system used in air traffic control (ATC), which

not only detects and measures the position of aircraft but also requests additional information from the aircraft itself such as its identity and altitude. Unlike primary radar systems, which measure only the range and bearing of targets by detecting reflected radio signals, rather like seeing an object in a beam of light, SSR relies on its targets being equipped with a radar transponder, which replies to each interrogation signal by transmitting its own response containing encoded data. SSR is based on the military identification friend or foe (IFF) technology originally developed during World War II, and the two

systems are still compatible today.

How it works • The aviation transponder was originally developed during World War II by the

British and American military as an "Identification friend or foe" (IFF) system to differentiate friendly from enemy aircraft on radar. The concept became a core of NORAD technology in the defence of North America during the Cold War.

• This concept was adapted in the 1950s by civil air traffic control using secondary surveillance radar (beacon radar) systems to provide traffic services for general aviation and commercial aviation.

• Secondary Surveillance Radar

Secondary Surveillance Radar is referred to as "secondary", to distinguish it from the "primary radar" that works by passively bouncing a radio signal off the skin of the aircraft. Primary radar works best with large all-metal aircraft, but not so well on small, composite aircraft. Its range is also limited by terrain, rain or snow and also detects unwanted objects such as automobiles, hills and trees. Furthermore not all primary radars can estimate the altitude of an aircraft. Secondary radar overcomes these limitations but it requires a radio transponder in the aircraft to respond to interrogation signals from the ground station to make the aircraft more visible and to report the aircraft's altitude.

How it works • Transponder modes• Operation

– A pilot may be requested to squawk a given code by the air traffic controller via the radio, using a phrase such as "Cessna 123AB, squawk 0363". The pilot then selects the 0363 code on their transponder and the track on the radar screen of the air traffic controller will become correctly associated with their identity.Because primary radar generally gives bearing and range position information, but lacks altitude information, mode C and mode S transponders also report pressure altitude. Around busy airspace there is often a regulatory requirement that all aircraft be equipped with an altitude-reporting mode C or mode S transponders. In the United States, this is known as a Mode C veil. Mode S transponders are compatible with transmitting the mode C signal, and have the capability to report in 25 foot increments. Without the pressure altitude reporting, the air traffic controller has no display of accurate altitude information, and must rely on the altitude reported by the pilot via radio. Similarly, the Traffic Collision Avoidance System installed on large aircraft as a last resort safety net needs the altitude information supplied by transponder signals.

• Ident– All mode A, C, and S transponders include an "ident" button, which activates a special

"thirteenth" bit on the mode A reply known as Ident, short for Identify. When radar equipment receives the Ident bit, it results in the aircraft's blip "blossoming" on the radar scope. This is often used by the controller to locate the aircraft amongst others by requesting the ident function from the pilot (e.g., "Cessna 123AB, squawk 0363 and ident").

– Ident can also be used in case of a reported or suspected radio failure to determine if the failure is only one way and whether the pilot can still transmit or receive but not both (e.g., "Cessna 123AB, if you read, squawk ident").

How it works • Transponder codes

Transponder codes are four digit numbers transmitted by the transponder in an aircraft in response to a secondary surveillance radar interrogation signal to assist air traffic controllers in traffic separation. A discrete transponder code (often called a squawk code) is assigned by air traffic controllers to uniquely identify an aircraft. This allows easy identity of the aircraft on radar.

Squawk codes are four-digit octal numbers; the dials on a transponder read from zero to seven inclusive. Thus the lowest possible squawk is 0000 and the highest is 7777. There are 4096 permutations of these four digit codes, which is why they are often called "4096 code transponders." Because these squawks are sensitive, care must be taken not to squawk any emergency code during a code change. For example, when changing from 1200 to 6501 (an assigned ATC squawk), one might turn the second wheel to a 5 (thus 1500), and then rotate the first wheel backwards in the sequence 1-0-7-6 to get to 6. This would momentarily have the transponder squawking a hijack code (7500), which might lead to more attention than one desires. Pilots are instructed not to place the transponder in "standby mode" while changing the codes as it causes the loss of target information on the ATC radar screen, but instead to carefully change codes to avoid inadvertently selecting an emergency code. Additionally, modern digital transponders are operated by buttons to avoid this problem.

There are other codes known as conspicuity codes which are not necessarily unique to a particular aircraft, but may have their own meaning and are used to convey information about the aircraft to ATC, possibly when the aircraft is not in radio contact.Codes 2000 and 7000 are examples of conspicuity codes.

The use of the word "squawk" comes from the system's origin in the World War II Identification Friend or Foe (IFF) system, which was code-named "Parrot". Parrot today generally refers to IFF only. The parrot check is generally done as part of the last-chance inspection at the runway, or after becoming airborne. Parrot sweet, and parrot sour are given, and the aircraft will have to abort in a real-world mission when sour, or face being attacked by friendly forces. Modern use of the word Parrot refers to a test transponder located at a fixed location off the radar facility. The parrot verifies range and direction accuracy of the radar facility.

How it works

• Electronic equipment in an aircraft that gives the pilot relative position information concerning nearby aircraft; some versions also display resolution advisories of maneuvers to avoid a collision. The system operates independently of ground-based air-traffic control equipment, but makes use of transponders carried by most aircraft to reply to air-traffic control surveillance.

• To achieve surveillance of aircraft carrying Air-Traffic Control Radar Beacon System (ATCRBS) transponders , TCAS transmits interrogations once per second using 0.8-microsecond pulses at 1030 MHz, in a format similar to those of the ground radars. The transponders reply with a block of 0.45-μs pulses at 1090 MHz, their sequence announcing the aircraft's barometric altitude quantized to the nearest 100 ft (30.5 m). TCAS measures the round-trip time from its interrogation to the received reply to determine the slant range, and decodes the altitude information contained in the reply sequence.

How it works Relation of the Traffic Alert and Collision Avoidance System (TCAS) to the existing air-traffic control system. TCAS interrogations elicit replies from transponders of nearby aircraft, enabling TCAS to show the pilot their relative position on a traffic display, and when appropriate, to issue a resolution advisory Here, TCAS instructs the pilot to descend to avoid a threat aircraft 300 ft above

How it works • The collision avoidance logic must distinguish a genuine collision threat from

routine safe passages. The relative range rate is derived from successive range reports. Likewise, an altitude rate is estimated from the other aircraft's altitude, and also for the system's aircraft. An estimate of the time of closest approach (τ) can be calculated from the equation below.

τ =RANGE / RANGE RATE

• Each nearby aircraft is evaluated once per second, and is deemed a threat if the range is already small or if τ is small, and if the relative altitude is predicted to be small. When a threat is declared, the effects of potential climb and descent maneuvers are estimated. The maneuver sense that gives the greater separation is chosen, except that a vertical crossing is not selected if the noncrossing sense gives adequate separation. An advisory is selected (such as limit climb; do not climb; descend) that is predicted to prevent a collision while minimizing the displacement from the aircraft's flight path

• An important part of TCAS is its traffic display, enabling crews to locate nearby traffic even when weather hinders visual sighting. At present, the format in use depicts nearby

aircraft in plan view, centered about the TCAS aircraft

How it works

AircraftIntruder

TCAS TRSP.Request

How it works

AircraftIntruder

TCAS TRSP.

Reply

How it works

• The system needs to find relative;– Bearing– Range– Altitude

How it works

• Bearing:Intruder

How it works

• Range:Intruder

How it works

• Altitude:Intruder

Embedded in either mode C or S reply

How it works

• Multiple requests:

Establish "track"

How it works

• Gives 3 different outputs depending on intruder equipment and range/bearing to intruder– Other traffic:

• Situational awareness

– Traffic Advisory: • Traffic within certain parameters, no steering

– Resolution Advisory: • Traffic within certain parameters, Steering

How it works

Aircraft Intruder

TCAS

mA

TA

How it works

Aircraft Intruder

TCAS

mA mC

mA

RA

TA

How it works

Aircraft Intruder

TCAS

mA mC

TCAS I

mA

RA

RA

TA

How it works

Aircraft Intruder

TCAS

mA mC

TCAS II

TCAS I

mA

Coord. RA

RA

RA

TA

How it works

TCAS

SurveillanceVolume

40 NM+/- 9900'

How it works

TCAS

SurveillanceVolume

6 NM+/- 1200'

How it works

TCAS

Other trafficRATA

30-45 s

20-30 s

How it works

TCAS

Other trafficRATA

30-45 s

20-30 s

Proximate traffic

Restrictions

• Can only give vertical guidance because;– System only uses;

• Altitude • Position• Closure rate• Vertical velocity to compute RA

– No aspect capability

Restrictions

?

TCAS - Philosophy

• TCAS increases safety!

• TCAS JAR Req. 1 Jan 00

• Safety paramount in aviation

• Technical solutions alone not enough

Breakdown in Quality system

Error

Flaps omitted

Deviation

Checklist failure

Amplification

Unheededwarning

Degradation "breakdown"

Quality system

Flapsomitted

Error Amplification

Effectivewarning

NormaloperationDeviation

Checklistworks

TCAS / - Future?

• 3D TCAS

• Sensor Fusion– AP– RNAV– GPS– EGPWS– TCAS– Other?

Zračni prostor • Flight plans

• A flight plan is filed with the authority providing air-traffic control services to convey information about the intended flight of the aircraft. All flight plans contain essentially the same information, that is, aircraft identification number, make and model, and color; planned true airspeed and cruising altitude; origin and destination airports; planned departure time and estimated time en route; planned route of flight, fuel, and number of people on board; pilot's name and address; navigation equipment on board; and the aircraft's radio call sign, if different from the aircraft identification number.

• A flight plan is not required for a flight under visual flight rules. However, if a flight plan is filed and the aircraft is overdue at its destination, search and rescue procedures will be initiated. Hence the flight plan under visual flight rules provides a significant safety benefit. An IFR flight plan is required for operation in controlled airspace when instrument meteorological conditions prevail.

Zračni prostor • Airspace

• The two principal categories of airspace are controlled and uncontrolled airspace. In controlled airspace some or all aircraft are required to operate in accordance with air-traffic control clearances in order to assure safety, to meet user needs for air-traffic control, or to accommodate high volumes of traffic. Air-traffic control services including air-to-ground communications and navigation aids are provided in controlled airspace. Uncontrolled airspace simply is airspace that has not been designated as controlled; air-traffic control services may not be available in such airspace.

• Two specific examples of controlled airspace are class A (the positive control area or PCA) and class B (the terminal control area or TCA). The positive control area is, with a few exceptions, the airspace within the conterminous 48 states and Alaska extending from 18,000 to 60,000 ft (5490 to 18,290 m) above mean sea level. Terminal control areas are centered on primary airports and extend from the surface to specified altitudes. An air-traffic control clearance and prescribed equipment are required prior to operating within a terminal control area regardless of weather conditions.

Zračni prostor • Air-to-ground communications

• Two-way air-to-ground voice communications between civil pilots and air-traffic controllers are conducted in the very high frequency (VHF) band. In addition, certain radio navigation aids can provide one-way communications from controllers to aircraft. These channels generally are used to broadcast weather and aeronautical information to pilots.

• Air-to-ground data communications (that is, data link) increasingly are used to transfer information to and from the cockpit. Many of the communications errors associated with humans incorrectly reading, speaking, and hearing text are eliminated by communications protocols that detect errors in data transmissions, by electronically displaying the information received, and by storing the received information so that it can be reviewed. Data link also permits large quantities of data to be exchanged between ground-based and airborne computers. Civil aviation is exploiting three data-link media: some VHF voice channels, Mode S, and communications satellites.

Zračni prostor

• Radio navigation aids

• Radio navigation aids are used to determine the plan position of the aircraft (that is, the position in the horizontal plane) in coordinates referenced either to the navigation aid or to the Earth (that is, latitude and longitude). For most operations, the aircraft vertical position is determined by sensing atmospheric pressure on board and converting this pressure to altitude, based on a standard model of the atmosphere. For the landing phase of flight, precision landing aids provide horizontal and vertical position referenced to the runway.

• VOR is a principal system used for determining plan position, with approximately 1000 ground stations nationwide. The system provides the magnetic azimuth from the VOR station to the receiving aircraft accurate to ±1°. Position determinations can be obtained from the intersection of radials from VORs with overlapping coverage volumes. With the addition of distance-measuring equipment at a VOR station, it is possible to obtain a position determination from a single station.

• Nondirectional radio beacon is an older technology, with few installations remaining. The system radiates a continuous signal from which direction-finding receivers can determine the azimuth to the ground station.

• Loran C is a pulsed system, with chains of ground stations each consisting of one master station and at least two secondary stations organized to transmit their signals in synchronism.

Zračni prostor

• Radio navigation aids

• In order to conduct approaches and landings in low-visibility conditions, it is necessary that an electronic glideslope (or glidepath) be provided as a reference for controlling the descent of the aircraft. In addition, a stable guidance signal is required to align the aircraft with the runway centerline. The instrument landing system (ILS) has been the standard means for providing precision landing guidance to the runway.The localizer antenna transmits the lateral (left and right) guidance signal over a 20° sector, 10° on both sides of the extended runway centerline. The glideslope antenna transmits the elevation guidance signal over a 1.4° sector, 0.7° on both sides of the glidepath, which is normally 3.0° above the horizontal.

• A new standard system for providing precision approach guidance, the microwave landing system (MLS) has been designed to eliminate limitations of the instrument landing system. It utilizes scanning-beam technology to provide proportional landing guidance over 80° in azimuth (40° on both sides of the extended runway centerline) and 15° in elevation. The system can provide three-dimensional landing guidance within the scanned volume, thereby permitting curved approaches and approaches at higher glideslope angles than those available from the instrument landing system.

Zračni prostor

• Radio navigation aids

• The constellation of Global Positioning System (GPS) satellites provides a highly accurate worldwide position determination and time transfer capability. In the horizontal plane, the position determined by a GPS receiver is within 330 ft (100 m) of the true receiver position at least 95% of the time. The vertical position is accurate to within 459 ft (140 m) on the same 95% probability basis. In addition, the receiver provides Coordinated Universal Time (UTC) with an accuracy of 310 ns (95% probability). Coordinated Universal Time is an internationally accepted time standard that never differs from Greenwich Mean Time by more than 1 s. The principal advantages of GPS are its accuracy and worldwide coverage

Zračni prostor

• Surveillance systems

• Air-traffic controllers use radar to monitor the positions of aircraft and to monitor areas of heavy precipitation. The radar information is used to develop clearances and instructions for separating aircraft operating under instrument flight rules, and to provide traffic advisories to IFR aircraft and to VFR aircraft receiving the traffic advisory service. Traffic advisories provide the ranges, bearings, and altitudes of aircraft in the pilot's immediate vicinity. The pilot is responsible for visually acquiring and avoiding any traffic that may be a collision threat. Two principal types of radar are used in civil air-traffic control: secondary, or beacon, radar and primary radar.

• Primary radar operates by transmitting high-power, radio-frequency pulses from a rotating directional antenna. The energy is reflected from any aircraft in the directional beam and received by the antenna. The aircraft is displayed at the azimuth corresponding to the pointing direction of the antenna and the range corresponding to the round-trip time between pulse transmission and receipt of the reflected signal. Primary radar has the advantage that aircraft without air-traffic control transponders can be detected, and energy reflected from heavy precipitation indicates to the controller areas of potentially hazardous weather. However, extraneous returns (clutter) from surrounding buildings and terrain can reduce the effectiveness of primary radar in detecting aircraft. At most air-traffic control radar sites, the secondary radar antenna is mounted on the primary radar antenna, and they are turned by a common drive system.

Zračni prostor

The antenna system of a typical ground radar. The ladder-like top section is the SSR directional antenna, and the remainder of the assembly makes up the PSR antenna.

Zračni prostor

• Surveillance systems

• Secondary radar is an interrogate-respond system. The rotating directional antenna of the ground station transmits a pulse pair to the transponder in the aircraft. The pulse spacing encodes one of two messages, “transmit your altitude” (the Mode C interrogation) or “transmit your identity” (the Mode A interrogation). The aircraft transponder transmits an encoded pressure-altitude reply in response to the first interrogation and a four-digit identity code, assigned by air-traffic control and entered into the transponder by the pilot, in response to the second system.

• The secondary radar system has been improved through the addition of Mode S, which employs more sophisticated signaling formats than Modes A and C. Each aircraft transponder is permanently assigned a unique address and interrogations therefore can be addressed to individual aircraft.

• In the oceanic environment, the ground-based surveillance systems described above obviously cannot be used. Oceanic operations are now based on rigid procedures and high-frequency (HF) communications that sometimes are unreliable. With the advent of commercially available mobile satellite communication systems, the development of a technique called automatic dependent surveillance (ADS) has been undertaken to provide real-time position information from aircraft over the ocean. In the operation of this system, the position of the aircraft, as determined from on-board navigation sensors, is communicated to air-traffic control facilities when requested by satellite relay. This position information can be displayed to controllers as though it had been determined by a radar system.

Navigacioni sistemi- VOR

Navigacioni sistemi- VOR

• A short-range air navigation aid, which provides azimuth aid by visual means of cockpit instruments. A VOR system provides properly equipped aircraft with bearing information relative to the VOR station and magnetic north. The VOR system is used for landing, terminal, and en route guidance. It also gives virtually static-free regular weather broadcasts, special flight instructions, and voice and code station identification. The VOR service operates in the very high frequency (VHF) band between 108 and 118 MHz, sharing alternate channels with the localizer in the instrument landing system. Typically, VOR stations are co-located with a distance measuring equipment (DME) system or a tactical are navigation (TACAN) system. The combined systems are referred to as VOR/DME or VORTAC stations and provide both azimuth and distance information.

• The VOR operates on the principle that the phase difference between two signals can be employed as a means of determining azimuth if one of the signals maintains a fixed phase through 360°, so it can be used as a reference, while the other is made to vary as a direct function of azimuth. The phase difference between these two signals will then equal the azimuth of the aircraft. In practice, two demodulated 30-Hz signals are used. These

are called the reference-phase and variable-phase signals.

Navigacioni sistemi- VOR

Postoje različiti oblici indikatora, od najjednostavnijeg do najkompleksnijih elektroničkih informacionih sistema letenja. Tri su tipa indikatora VOR-a:

Indikator radio kompasa (RMI) Birač radijala VOR-a (OBS) Prikazivač horizontalne situacije (HSI) Prostorna navigacija (RNAV)

Navigacioni sistemi- VOR

RMI kombinuje informaciju sa radio navigacionih instrumenata sa informacijom pravca koju pokazuje žiroskop. RMI ima dvije iglice, koje prikazuju ADF (Automatic Direction Finding) i VOR informaciju. Iglice obično imaju jednu samostalnu liniju i uduplanu liniju kako bi olakšali posadi identifikaciju stanica.

Indikatorske igle stalno ukazuju na podešenu stanicu. RMI je podešen žiropolukompasom, tako da se magnetski kurs zrakoplova ili heading, može očitati direktno sa reperne linije kompasa na vrhu. U ovom slučaju, iglicie pokazuju kurs ka zemaljskim stanicama:Vrh iglica ukazuje na magnetski kurs ka zemaljskim stanicama, QDMRepni dio iglica pokazuje magnetski kurs od zemaljske stanice ka zrakoplovu, QDR Kada je podešen VOR, kraj iglice pokazuje radijal VOR-a. Na slici, tanka ili samostalna iglica usmjerena ka VOR stanici, pokazuje da je zrakoplov na radijalu 195°. Markirna iglica sa uduplanom linijom pokazuje QDM 302° (QDR 122°).

Navigacioni sistemi- VOR

- OBS selektorPomoću ovog selektora pilot odabira željeni magnetni kurs, odnosno da li želi da ide ka VORU-u ili dolozi od njega. Prema slici 5., pilot je odabrao 100-ti radijal. - Indikator TO/FROMKada je zahtjevani magnetni kurs postavljen, strjelica TO ili FROM se pojavljuje na osnovu položaja zrakoplova u odnosu na radio far odnosno VOR. Na slici 4. to je strjelica TO. Indikacija se mjenja kada zrakoplov pređe preko VOR-a na koji je bio nastrojen.

Indikator odstupanja od kursa

Indikator posjeduje 4 male tačke i jednu centralnu veliku. Svaka od tačaka predstavlja 2°, sa potpunim otklonom igle od 10°. Vertikalna crta se pomjera lijevo ili desno shodno trenutnoj poziciji zrakoplova u odnou na postavljeni magnetni kurs. Kada je crta na sredini, zrakoplov je na zadanom magnetnom kursu. Na slici 4. je prikazano odstupanje od 3,5 tačaka lijevo, što znači da zrakoplov odstupa od zadatog kursa za 7°. Da bi se vratio na zadati kurs, odnosno da bi se crta postavila u vertikalan položaj na sredini, potrebno je da zrakoplov skrene u lijevo.

Navigacioni sistemi- VOR1 HSI omogućava slikovitu prezentaciju odstupanja zrakoplova u odnosu na radijal VOR-a ili snop localiser-a. Prikazuje i odstupanja od ravni poniranja i referentni heading prema magnetnom sjeveru.2 Navigaciona zastavica (NAV) je prikazana kada je prijemnik signala neadekvatan. Kada je prikazana zastavica, navigacioni indikator operacije autopilota nije uticajan. Posada mora monitorisati navigacioni indikator zbog NAV zastavice, kako bi bili sigurni da Autopilot i/ili Flight Director daju validan navigacioni podatak.3 Reperna linija pokazuje magnetni heading na kompasnoj karti (10).4 Heading zastavica upozorenja (HDG) je prikazana kada je displej heading-a netačan. Ako se HDG pojavi a seloktovani su bočni modovi (HDG, NAV, APR ili APR BC), autopilot se isključuje. Moguće je ponovo uključiti autopilot u osnovnom wings-level modu skupa sa bilo kojim vertikalnim modom.5 Pointer izabranog kursa pokazuje selektovani kurs VOR-a ili localiser-a na kompas karti (10). Selektovani radijal VOR-a ili heading localiser-a biva postavljen na kompas karti kada se karta rotira.6 Indikatorska zastavica TO/FROM pokazuje smjer VOR stanice u odnosu na selektovani kurs.

7 Dupli pokazivači ravni poniranja na skali pokazuju otklon zrakoplova od centra snopa ravni poniranja. Kazaljke ravni poniranja pokazuju prihvat korisnog signala ravni poniranja. Ukoliko je signal izgubljen neće biti nikakvih indikacija.8 Skale ravni poniranja pokazuju otklon od centra snopa ravni poniranja. Odstupanje od dvije tačke predstavlja otklon od 7° iznad ili ispod centralne linije snopa ravni poniranja .9 Dugme za selekciju heading-a, pozicionira heading (14) na karti kompasa (10). Greška se rotira sa kopasnom kartom.10 Kompasna karta rotira se, kako bi se prikazao heading zrakoplova koji je referentan ka repernoj liniji (3) na HSI-u.11 Dugme za selekciju kursa, pozicionira kazaljku kursa (5) na kompasnoj karti (10) okretanjem dugmeta za selekciju kursa.12 Bar odstupanja od kursa (D-BAR) pomjera se bočno kako bi slikovito ukazao na odnos zrakoplova prema selektovanom kursu korištenjem centralne pozicije selektora radijala (OBS). Pokazuje stepene ugaonog otklona od VOR radijala i snopa localiser-a, ili otklon u nautičkim miljama od RNAV (Area Navigation) kursa.13 Skala odstupanja od kursa funkcionira sa D-BAR-om od pet tačaka prezentujući odstupanje od centralne linije snopa (VOR = 10° , LOC = 2.5°, RNAV = 5 NM, RNAV APR = 1NM).8Heading strjelica prikazuje željeni heading, selektovan korištenjem heading dugmeta (9).

Navigacioni sistemi- VOR

Navigacioni sistemi- VOR

A Rotating Course Card, calibrated from 0 to 360°, which indicates the VOR bearing chosen as the reference to fly TO or FROM. Here, the 345° radial has been set into the display. This VOR gauge also digitally displays the VOR bearing, which simplifies setting the

desired navigation track.

C The CDI, or Course Deviation Indicator. This needle swings left or right indicating the direction to turn to return to course. When the needle is to the left, turn left and when the needle is to the right, turn right, When centered, the aircraft is on course. Each dot in the arc under the needle represents a 2° deviation from the desired course. This needle is more-frequently called the left-right needle, with the CDI term quickly forgotten after taking the FAA written exams. Here, the pilot is doing well, and is dead-

on course—or maybe lazy and with the autopilot activated in the "NAV" mode

B The Omni Bearing Selector, or OBS knob, used to manually rotate the course

card.

Navigacioni sistemi- VOR

This aircraft is north of the Omni station, flying on the 345° radial away FROM the station. The left-right needle shows the aircraft on course and the FROM flag is present, pointing down, toward the station behind.

Navigacioni sistemi- VOR

This aircraft is south of the Omni station. Its magnetic course is 345°.

Navigacioni sistemi- VOR

The aircraft isn't on the 345° radial because that radial extends from the Omni to the northwest as shown by the arrow. The aircraft is actually on the reciprocal radial, the radial pointing towards the plane. That reciprocal radial is 165°, away from the station like all radials. If the 165° radial were set into the VOR, the FROM flag would properly show, because the aircraft is away from the Omni on that radial. Here is the important point. If the OBS is rotated until the needle centers and the FROM flag shows, it will always show the correct radial from the Omni that the aircraft is on regardless of the aircraft heading. To eliminate the confusion of location relative to an Omni, the magnetic course of the aircraft and the radial setting on the VOR should be the same. Presumably the aircraft is flying in the desired course direction, so its heading will be approximately the same as the VOR setting, i.e., the magnetic course. The heading may differ slightly from the VOR because of the correction needed to correct for wind drift. Thus, with the OBS set to 345° the left-right needle shows the aircraft on course and the TO flag is showing, pointing up,

toward the station ahead.

Navigacioni sistemi- VOR

This aircraft has drifted to the right of the desired course. To be "on course" the aircraft must be on the red line. Not paying attention to a crosswind (what other kind is there?), or simply letting the heading wander could do it. In any event, the VOR needle has swung to the left, indicating that the aircraft must move to the left to return to course. So a left turn is in order. Like the RMI, with the VOR a pilot always turns towards the needle to return to course, assuming that the OBS setting approximates the aircraft heading.

This aircraft is 4° off course. Each dot of the arc under the needle is a 2° deviation from the desired course. Don't confuse heading, the direction of the aircraft's nose, with course, the desired track along the ground. Only with no wind will heading and course be the same.

Navigacioni sistemi- VOR

• VOR and the older NDB stations were traditionally used as intersections along airways. A typical airway will hop from station to station in straight lines. As you fly in a commercial airliner you will notice that the aircraft flies in straight lines occasionally broken by a turn to a new course. These turns are often made as the aircraft passes over a VOR station or at an intersection in the air

defined by one or more VORs .

Navigacioni sistemi- VOR• Navigational reference points can also be defined by the point at which two

radials from different VOR stations intersect, or by a VOR radial and a DME distance. This is the basic form of RNAV and allows navigation to points located away from VOR stations. As RNAV systems have become more common, in particular those based upon GPS, more and more airways have been defined by such points, removing the need for some of the expensive ground-based VORs. A recent development is that, in some airspace, the need for such points to be defined with reference to VOR ground stations has been removed. This has led to predictions that VORs will be obsolete within a decade or so.

• There are three types of VORs: High Altitude, Low Altitude and Terminal. The range of the three differ. Terminal VORs are accurate to 25 NM outward up to 12,000 ft.

• In many countries there are two separate systems of airway at lower and higher levels: the lower Airways (known in the US as Victor Airways) and Upper Air Routes (known in the US as Jet routes).

• Most aircraft equipped for instrument flight (IFR) have at least two VOR receivers. As well as providing a backup to the primary receiver, the second receiver allows the pilot to easily follow a radial toward one VOR station while watching the second receiver to see when a certain radial from another VOR station is crossed, essentially seeing when a particular fix is crossed.

Navigacioni sistemi- VOR

The information is then fed to one of four common types of indicators:

• An Omni-Bearing Indicator (OBI) is the typical light-airplane VOR indicator [3] and is shown in the accompanying illustration. It consists of a knob to rotate an "Omni Bearing Selector" (OBS), and the OBS scale around the outside of the instrument, used to set the desired course. A "course deviation indicator" (CDI) is centered when the aircraft is on the selected course, or gives left/right steering commands to return to the course. An "ambiguity" (TO-FROM) indicator shows whether following the selected course would take the aircraft to, or away from the station.

• A Horizontal Situation Indicator (HSI) is considerably more expensive and complex than a standard VOR indicator, but combines heading information with the navigation display in a much more user-friendly format, approximating a simplified moving map.

• A Radio Magnetic Indicator (RMI), developed previous to the HSI, features a course arrow superimposed on a rotating card which shows the aircraft's current heading at the top of the dial. The "tail" of the course arrow points at the current radial from the station, and the "head" of the arrow points at the reciprocal (180 degrees different) course to the station.

• An Area Navigation (RNAV) system is an onboard computer, with display, and up-to-date navigation database. At least two VOR stations, or one VOR/DME station is required, for the computer to plot aircraft position on a moving map, or display course deviation relative to a waypoint (virtual VOR station).

Navigacioni sistemi- vor• If a pilot wants to approach the VOR station from due east then the aircraft

will have to fly due west to reach the station. The pilot will use the OBS to rotate the compass dial until the number 27 (270 degrees) aligns with the pointer (called the Primary Index) at the top of the dial. When the aircraft intercepts the 90-degree radial (due east of the VOR station) the needle will be centered and the To/From indicator will show "To". Notice that the pilot sets the VOR to indicate the reciprocal; the aircraft will follow the 90-degree radial while the VOR indicates that the course "to" the VOR station is 270 degrees. This is called "proceeding inbound on the 090 radial." The pilot needs only to keep the needle centered to follow the course to the VOR station. If the needle drifts off-center the aircraft would be turned towards the needle until it is centered again. After the aircraft passes over the VOR station the To/From indicator will indicate "From" and the aircraft is then proceeding outbound on the 270 degree radial. The CDI needle may oscillate or go to full scale in the "cone of confusion" directly over the station but will recenter once the aircraft has flown a short distance beyond the station.

• In the illustration on the right, notice that the heading ring is set with 360 degrees (North) at the primary index, the needle is centred and the To/From indicator is showing "TO". The VOR is indicating that the aircraft is on the 360 degree course (North) to the VOR station (i.e. the aircraft is South of the VOR station). If the To/From indicator were showing "From" it would mean the aircraft was on the 360 degree radial from the VOR station (i.e. the aircraft is North of the VOR). Note that there is absolutely no indication of what direction the aircraft is flying. The aircraft could be flying due West and this snapshot of the VOR could be the moment when it crossed the 360 degree radial

Navigacioni sistemi- DME

• A short-range Distance measuring equipment (DME) is a transponder-based radio navigation technology that measures distance by timing the propagation delay of VHF or UHF radio signals.

• Aircraft use DME to determine their distance from a land-based transponder by sending and receiving pulse pairs - two pulses of fixed duration and separation. The ground stations are typically co-located with VORs. A typical DME ground transponder system for en-route or terminal navigation will have a 1 kW peak pulse output on the assigned UHF channel. A low-power DME can also be co-located with an ILS glide slope or localizer where it provides an accurate distance function, similar to that otherwise provided by ILS Marker Beacons.

• The DME system is composed of a UHF transmitter/receiver (interrogator) in the aircraft and a UHF

receiver/transmitter(transponder) on the ground.

Navigacioni sistemi- DME• Timing• The aircraft interrogates the ground transponder with a series of pulse-pairs (interrogations) and,

after a precise time delay (typically 50 microseconds), the ground station replies with an identical sequence of reply pulse-pairs. The DME receiver in the aircraft searches for pulse-pairs (X-mode= 12 microsecond spacing) with the correct time interval between them, which is determined by each individual aircraft's particular interrogation pattern. The aircraft interrogator locks on to the DME ground station once it understands that the particular pulse sequence is the interrogation sequence it sent out originally. Once the receiver is locked on, it has a narrower window in which to look for the echoes and can retain lock.

• Distance calculation• A radio pulse takes around 12.36 microseconds to travel 1 nautical mile (1,852 m) to and from;

this is also referred to as a radar-mile. The time difference between interrogation and reply 1 nautical mile (1,852 m) minus the 50 microsecond ground transponder delay is measured by the interrogator's timing circuitry and translated into a distance measurement in nautical miles, which is then displayed in the cockpit.

• The distance formula, distance = rate * time, is used by the DME receiver to calculate its distance from the DME ground station. The rate in the calculation is the velocity of the radio pulse, which is the speed of light (roughly 300,000,000 m/s or 186,000 mi/s). The time in the calculation is (total time - 50µs)/2.

• Specification• A typical DME transponder can provide distance information to 100 aircraft at a time. Above this

limit the transponder avoids overload by limiting the gain of the receiver. Replies to weaker more distant interrogations are ignored to lower the transponder load. DME can be used by 300 users at one time. The technical term of the DME station when its overloaded and cannot accept more than 100 aircraft is called station saturation.

Navigacioni sistemi- DME• Radio frequency and modulation data• DME frequencies are paired to VHF omnidirectional range (VOR) frequencies and a DME

interrogator is designed to automatically tune to the corresponding DME frequency when the associated VOR frequency is selected. An airplane’s DME interrogator uses frequencies from 1025 to 1150 MHz. DME transponders transmit on a channel in the 962 to 1150 MHz range and receive on a corresponding channel between 962 to 1213 MHz. The band is divided into 126 channels for interrogation and 126 channels for reply. The interrogation and reply frequencies always differ by 63 MHz. The spacing of all channels is 1 MHz with a signal spectrum width of 100 kHz.

• Technical references to X and Y channels relate only to the spacing of the individual pulses in the DME pulse pair, 12 microsecond spacing for X channels and 30 microsecond spacing for Y channels.

• DME facilities identify themselves with a 1350 Hz morse code three letter identity. If collocated with a VOR or ILS, it will have the same identity code as the parent facility. Additionally, the DME will identify itself between those of the parent facility. The DME identity is 1350 Hz to differentiate itself from the 1020 Hz tone of the VOR or the ILS localizer.

• Accuracy• The accuracy of DME ground stations is 185 m (±0.1 nm).[It's important to understand that DME

provides the physical distance from the aircraft to the DME transponder. This distance is often referred to as 'slant range' and depends trigonometrically upon both the altitude above the transponder and the ground distance from it.

• For example, an aircraft directly above the DME station at 6000 ft (1 nmi) altitude would still show 1.0 nmi (1.9 km) on the DME readout. The aircraft is technically a mile away, just a mile straight up. Slant range error is most pronounced at high altitudes when close to the DME station.

• Radio-navigation aids must keep a certain degree of accuracy, given by international standards, FAA.,ICAO, etc. To assure this is the case, flight inspection organizations check periodically critical parameters with properly equipped aircraft to calibrate and certify DME precision.

Navigacioni sistemi- VOR/DME

• In many cases, VOR stations have co-located DME (Distance Measuring Equipment) or military TACAN (TACtical Air Navigation) — the latter includes both the DME distance feature and a separate TACAN azimuth feature that provides military pilots data similar to the civilian VOR. A co-located VOR and TACAN beacon is called a VORTAC. A VOR co-located only with DME is called a VOR-DME. A VOR radial with a DME distance allows a one-station position fix. Both VOR-DMEs and TACANs share the same DME system.

• VORTACs and VOR-DMEs use a standardized scheme of VOR frequency to TACAN/DME channel pairing so that a specific VOR frequency is always paired with a specific co-located TACAN or DME channel. On civilian equipment, the VHF frequency is tuned and the appropriate TACAN/DME channel is automatically selected.

Navigacioni sistemi- VOR/DME

• A VOR station serves a volume of airspace called its Service Volume. Some VORs have a relatively small geographic area protected from interference by other stations on the same frequency—called "terminal" or T-VORs. Other stations may have protection out to 130 nautical miles (NM) or more. Although it is popularly thought that there is a standard difference in power output between T-VORs and other stations, in fact the stations' power output is set to provide adequate signal strength in the specific site's service volume.

A worldwide land-based network of "air highways", known in the US as Victor airways (below 18,000 feet) and "jet routes" (at and above 18,000 feet), was set up linking VORs. An aircraft can follow a specific path from station to station by tuning the successive stations on the VOR receiver, and then either following the desired course on a Radio Magnetic Indicator, or setting it on a Course Deviation Indicator (CDI) or a Horizontal Situation Indicator (HSI, a more sophisticated version of the VOR indicator) and keeping a

course pointer centered on the display.

VOR

VORTAC

VOR-DME

Navigacioni sistemi- DME• This information is then fed to one of four common types of indicators:

• An Omni-Bearing Indicator (OBI) is the typical light-airplane VOR indicator and is shown in the accompanying illustration. It consists of a knob to rotate an "Omni Bearing Selector" (OBS), and the OBS scale around the outside of the instrument, used to set the desired course. A "course deviation indicator" (CDI) is centered when the aircraft is on the selected course, or gives left/right steering commands to return to the course. An "ambiguity" (TO-FROM) indicator shows whether following the selected course would take the aircraft to, or away from the station.

• A Horizontal Situation Indicator (HSI) is considerably more expensive and complex than a standard VOR indicator, but combines heading information with the navigation display in a much more user-friendly format, approximating a simplified moving map.

• A Radio Magnetic Indicator (RMI), developed previous to the HSI, features a course arrow superimposed on a rotating card which shows the aircraft's current heading at the top of the dial. The "tail" of the course arrow points at the current radial from the station, and the "head" of the arrow points at the reciprocal (180 degrees different) course to the station.

• An Area Navigation (RNAV) system is an onboard computer, with display, and up-to-date navigation database. At least two VOR stations, or one VOR/DME station is required, for the computer to plot aircraft position on a moving map, or display course deviation relative to a waypoint (virtual VOR station).

Navigacioni sistemi- VOR/DME

• Area Navigation (RNAV) is a method of Instrument Flight Rules (IFR) navigation that allows an aircraft to choose any course within a network of navigation beacons, rather than navigating directly to and from the beacons. This can conserve flight distance, reduce congestion, and allow flights into airports without beacons. RNAV can be defined as a method of navigation that permits aircraft operation on any desired course within the coverage of station-referenced navigation signals or within the limits of a self-contained system capability, or a combination of these.

DME • When used in conjunction with the VOR system, DME makes it possible for

pilots to determine an accurate geographic position of the aircraft, including the bearing and distance TO or FROM the station. The aircraft DME transmits interrogating radio frequency (RF) pulses, which are received by the DME antenna at the ground facility. The signal triggers ground receiver equipment to respond to the interrogating aircraft. The airborne DME equipment measures the elapsed time between the interrogation signal sent by the aircraft and reception of the reply pulses from the ground station. This time measurement is converted into distance in nautical miles (NM) from the station.

• Some DME receivers provide a groundspeed in knots by monitoring the rate of change of the aircraft’s position relative to the ground station. Groundspeed values are accurate only when tracking directly to or from the station.

• VOR/DME, VORTAC, ILS/DME, and LOC/DME navigation facilities provide course and distance information from collocated components under a frequency pairing plan. DME operates on frequencies in the UHF spectrum between 962 MHz and 1213 MHz. Aircraft receiving equipment which provides for automatic DME selection assures reception of azimuth and distance information from a common source when designated VOR/DME, VORTAC, ILS/DME, and LOC/DME are selected. Some aircraft have separate VOR and DME receivers, each of which must be tuned to the appropriate navigation facility. The airborne equipment includes an antenna and a receiver.

RNAV RNAV specifications include requirements for certain navigation functions.

These functional requirements include:

• continuous indication of aircraft position relative to track to be displayed to the pilot flying on a navigation display situated in his primary field of view;

• display of distance and bearing to the active (To) waypoint;

• display of ground speed or time to the active (To) waypoint;

• navigation data storage function; and

• appropriate failure indication of the RNAV system including its sensors.

Channel (Frequency) Selector

Many DMEs are channeled by an associated VHF radio, or there may be a selector switch so a pilot can select which VHF radio is channeling the DME. For a DME with its own frequency selector, use the frequency of the associated VOR/DME or VORTAC station.

On/Off/Volume Switch

The DME identifier will be heard as a Morse code identifier with a tone somewhat higher than that of the associated VOR or LOC. It will be heard once for every three or four times the VOR or LOC identifier is heard. If only one identifier is heard about every 30 seconds, the DME is functional, butthe associated VOR or LOC is not.

Mode Switch

The mode switch selects between distance (DIST) or distance in NMs, groundspeed, and time to station. There may also be one or more HOLD functions which permit the DME to stay channeled to the station that was selected before the switch was placed in the hold position. This is useful when you make an ILS approach at a facility that has no collocated DME, but there is a VOR/DME nearby.

DME

Function of DME

A DME is used for determining the distance from a ground DME transmitter. Compared to other VHF/UHF NAVAIDs, a DME is very accurate. The distance information can be used to determine the aircraft position or flying a track thatis a constant distance from the station. This is referred to as a DME arc.

DME Arc

There are many instrument approach procedures (IAPs) that incorporate DME arcs. The procedures and techniques given here for intercepting and maintaining such arcs are applicable to any facility that provides DME information. Such a facility may or may not be collocated with the facility that provides final approach guidance.

DME

DME

1. Track inbound on the OKT 325° radial, frequently checking the DME mileage readout.

2. A 0.5 NM lead is satisfactory for groundspeeds of 150 knots or less; start the turn to the arc at 10.5 miles. At higher ground speeds, use a proportionately greater lead.

3. Continue the turn for approximately 90°. The roll-out heading will be 055° in a no wind condition.

4. During the last part of the intercepting turn, monitor the DME closely. If the arc is being overshot (more than 1.0 NM), continue through the originally planned roll-out heading. If the arc is being undershot, roll-out of the turn early.

An aeronautical chart is the road map for a pilot flying under VFR. The chart provides information which allows pilots to track their position and provides available information which enhances safety. The three aeronautical charts used by VFR pilots are:

• Sectional • VFR Terminal Area • World Aeronautical

Sectional charts are the most common charts used by pilots today. The charts have a scale of 1:500,000 (1 inch = 6.86 nautical miles (NM) or approximately 8 statute miles (SM)) which allows for more detailed information to be included on the chart.The charts provide an abundance of information, including airport data, navigational aids, airspace, and topography. Figure is an excerpt from the legend of a sectional chart. By referring to the chart legend, a pilot can interpret most of the information on the chart. A pilot should also check the chart for other legend information, which includes air traffic control (ATC) frequencies and information on airspace. These charts are revised semiannually.

AERONAUTICHAL CHARTS

SECTIONAL AERONAUTICHAL CHARTS

VFR TERMINAL AERONAUTICHAL CHARTS

VFR terminal area charts are helpful when flying in or near Class B airspace. They have a scale of 1:250,000 (1 inch = 3.43 NM or approximately 4 SM). These charts provide a more detailed display of topographical information and are revised semiannually

WORLD AERONAUTICHAL CHARTS

World aeronautical charts are designed to provide a standard series of aeronautical charts, covering land areas of the world, at a size and scale convenient for navigation by moderate speed aircraft. They are produced at a scale of 1:1,000,000 (1 inch = 13.7 NM or approximately 16 SM). These charts are similar to sectional charts and the symbols are the same except there is less detail due to the smaller scale. These charts are revised annually.

The ILS system provides both course and altitude guidance to a specific runway. The ILS system is used to execute a precision instrument approach procedure or precision approach. The system consists of the following components:

1. A localizer providing horizontal (left/right) guidancealong the extended centerline of the runway.

2. A glide slope (GS) providing vertical (up/down)guidance toward the runway touchdown point, usuallyat a 3° slope.

3. Marker beacons providing range information alongthe approach path.

4. Approach lights assisting in the transition frominstrument to visual flight.

ILS

ILS Components

• Localizer – indicates alignment w/ runway

• Glideslope – indicates correct descent path

• Outer Marker – Final Approach Fix

• Middle Marker – Missed Approach Point

ILS

ILS

Localizer

Needle indicates direction of runway.

Centered Needle = Correct Alignment

ILS

LocalizerThe localizer (LOC) ground antenna array is located on the extended centerline of the instrument runway of an airport, located at the departure end of the runway to prevent it from being a collision hazard. This unit radiates a field pattern, which develops a course down the centerline of the runway toward the middle markers (MMs) and outer markers (OMs), and a similar course along the runway centerline in the opposite direction. These are called the front and back courses, respectively. The localizer provides course guidance, transmitted at 108.1 to 111.95 MHz (odd tenths only), throughout the descent path to the runway threshold from a distance of 18 NM from the antenna to an altitude of 4,500 feet above the elevation of the antenna site.

The localizer course width is defined as the angular displacement at any point along the course between a full “fly-left” (CDI needle fully deflected to the left) and a full “fly-right” indication (CDI needle fully deflected to the right). Each localizer facility is audibly identified by a three-letter designator, transmitted at frequent regular intervals. The ILS identification is preceded by the letter “I” (two dots). The localizer includes a voice feature on its frequency for use by the associated ATC facility in issuing approach and landing instructions.The localizer course is very narrow, normally 5°. This results in high needle sensitivity. With this course width, a full-scale deflection shows when the aircraft is 2.5° to either side of the centerline. This sensitivity permits accurate orientation to the landing runway. With no more than onequarter scale deflection maintained, the aircraft will be aligned with the runway.

ILS KOMPONENTE

ILS KOMPONENTE

Glide Slope (GS)

GS describes the systems that generate, receive, and indicate the ground facility radiation pattern. The glide path is the straight, sloped line the aircraft should fly in its descent from

where the GS intersects the altitude used for approaching the FAF, to the runway touchdown zone. The GS equipment is housed in a building approximately 750 to 1,250 feet

down the runway from the approach end of the runway, and between 400 and 600 feet to one side of the centerline.

The course projected by the GS equipment is essentially the same as would be generated by a localizer operating on its side. The GS projection angle is normally adjusted to 2.5°

to 3.5° above horizontal, so it intersects the MM at about 200 feet and the OM at about 1,400 feet above the runway elevation. At locations where standard minimum obstruction clearance cannot be obtained with the normal maximum GS angle, the GS equipment is displaced farther from the approach end of the runway if the length of the runway permits; or, the GS angle may be increased up to 4°.

Unlike the localizer, the GS transmitter radiates signals only in the direction of the final approach on the front course. The system provides no vertical guidance for approaches on the back course. The glide path is normally 1.4° thick. At 10 NM from the point of touchdown, this represents a vertical distance of approximately 1,500 feet, narrowing to a few feet at touchdown.

ILS KOMPONENTE

Glideslope

Needle indicates above/below glidepath.

Centered Needle = Correct Glidepath

Runway

Correct Glidepath

Descent Cone

ILS KOMPONENTE

ILS

ILS

ILS

ILS

ILS

ILS

ILS

The following supplementary elements, though not specific components of the system, may be incorporated to increase safety and utility:

1.Compass locators providing transition from en route NAVAIDs to the ILS system and assisting in holding procedures, tracking the localizer course, identifying the marker beacon sites, and providing a FAF for ADF approaches.2. DME collocated with the GS transmitter providing positive distance-to-touchdown information or DME associated with another nearby facility (VOR or standalone), if specified in the approach procedure.

ILS approaches are categorized into three different types of approaches based on the equipment at the airport and the experience level of the pilot. Category I approaches provide for approach height above touchdown of not less than 200 feet. Category II approaches provide for approach to a height above touchdown of not less than 100 feet. Category III approaches provide lower minimums for approaches without a decision height minimum. While pilots need only be instrument rated and the aircraft be equipped with the appropriate airborne equipment to execute Category I approaches, Category II and III approaches require special certification for the pilots, ground equipment, and airborne equipment.

ILS

Marker Beacons

Two VHF marker beacons, outer and middle, are normally used in the ILS system. A third beacon, the inner, is used where Category II operations are certified. A marker beacon may also be installed to indicate the FAF (final approach fix) on the ILS back course.

The OM is located on the localizer front course 4–7 miles from the airport to indicate a position at which an aircraft, at the appropriate altitude on the localizer course, will intercept the glide path. The MM is located approximately 3,500 feet from the landing threshold on the centerline of the localizer front course at a position where the GS centerline is about 200 feet above the touchdown zone elevation. The inner marker (IM), where installed, is located on the front course between the MM and the landing threshold. It indicates the point at which an aircraft is at the decision height on the glide path during a Category II ILS approach. The back-course marker, where installed, indicates the back-course FAF.

ILS KOMPONENTE

ILS Airborne Components

Airborne equipment for the ILS system includes receivers for the localizer, GS, marker beacons, ADF, DME, and the respective indicator instruments.

The typical VOR receiver is also a localizer receiver with common tuning and indicating equipment. Some receivers have separate function selector switches, but most switch between VOR and LOC automatically by sensing if odd tenths between 108 and 111.95 MHz have been selected. Otherwise, tuning of VOR and localizer frequencies is

accomplished with the same knobs and switches, and the CDI indicates “on course” as it does on a VOR radial. Though some GS receivers are tuned separately, in a typical

installation the GS is tuned automatically to the proper frequency when the localizer is tuned. Each of the 40 localizer channels in the 108.10 to 111.95 MHz band is paired with a corresponding GS frequency.

When the localizer indicator also includes a GS needle, the instrument is often called cross-pointer indicator. The crossed horizontal (GS) and vertical (localizer) needles are

free to move through standard five-dot deflections to indicate position on the localizer course and glide path. When the aircraft is on the glide path, the needle is horizontal, overlying the reference dots. Since the glide path is much narrower than the localizer course (approximately 1.4° from full up to full down deflection), the needle is very sensitive

to displacement of the aircraft from on-path alignment. With the proper rate of descent established upon GS interception, very small corrections keep the aircraft aligned.

ILS KOMPONENTE

ILS Airborne Components

The localizer and GS warning flags disappear from view on the indicator when sufficient voltage is received to actuate the needles. The flags show when an unstable signal or receiver malfunction occurs.

The OM is identified by a low-pitched tone, continuous dashes at the rate of two per second, and a purple/blue marker beacon light. The MM is identified by an intermediate tone, alternate dots and dashes at the rate of 95 dot/dash combinations per minute, and an amber marker beacon light. The IM, where installed, is identified by a high-pitched tone, continuous dots at the rate of six per second, and a white marker beacon light.

The back-course marker (BCM), where installed, is identified by a high-pitched tone with two dots at a rate of 72 to 75 twodot combinations per minute, and a white marker beacon light.

Marker beacon receiver sensitivity is selectable as high or low on many units. The low-sensitivity position gives the sharpest indication of position and should be used during an approach. The high-sensitivity position provides an earlier warning that the aircraft is approaching the marker beacon site.

ILS FunctionThe localizer needle indicates, by deflection, whether the aircraft is right or left of the

localizer centerline, regardless of the position or heading of the aircraft. Rotating the OBS has no effect on the operation of the localizer needle, although it is useful to rotate the OBS to put the LOC inbound course under the course index. When inbound on the front course, or outbound on the back course, the course indication remains directional.

ILS KOMPONENTE

ILS KOMPONENTE

ILS Function

The localizer needle indicates, by deflection, whether the aircraft is right or left of the localizer centerline, regardless of the position or heading of the aircraft. Rotating the OBS has no effect on the operation of the localizer needle, although it is useful to rotate the OBS to put the LOC inbound course under the course index. When inbound on the front course, or outbound on the back course, the course indication remains directional. (Figure , aircraft C, D, and E.)

Unless the aircraft has reverse sensing capability and it is in use, when flying inbound on the back course or outbound on the front course, heading corrections to on-course are made opposite the needle deflection. This is commonly described as “flying away from the needle.” (Figure , aircraft A and B.) Back course signals should not be used for an approach unless a back course approach procedure is published for that particular runway and the approach is authorized by ATC.

Once you have reached the localizer centerline, maintain the inbound heading until the CDI moves off center. Drift corrections should be small and reduced proportionately as the course narrows. By the time you reach the OM, your drift correction should be established accurately enough on a wellexecuted approach to permit completion of the approach, with heading corrections no greater then 2°.

ILS KOMPONENTE

ILS Function

The heaviest demand on pilot technique occurs during descent from the OM to the MM, when you maintain the localizer course, adjust pitch attitude to maintain the proper rate of descent, and adjust power to maintain proper airspeed. Simultaneously, the altimeter must be checked and preparation made for visual transition to land or for a missed approach. You can appreciate the need for accurate instrument interpretation and aircraft control within the ILS as a whole, when you notice the relationship between CDI and glide path needle indications, and aircraft displacement from the localizer and glide path centerlines. Deflection of the GS needle indicates the position of the aircraft with respect to the glide path. When the aircraft is above the glide path, the needle is deflected downward. When the aircraft is below the glide path, the needle is deflected upward.

ILS KOMPONENTE

ILS

The MLS provides precision navigation guidance for exact alignment and descent of aircraft on approach to a runway. It provides azimuth, elevation, and distance. Both lateral and vertical guidance may be displayed on conventional course deviation indicators or incorporated into multipurpose flight deck displays. Range information can be displayedby conventional DME indicators and also incorporated into multipurpose displays. The system may be divided into five functions, which are approach azimuth, back azimuth, approach elevation, range; and data communications. The standard configuration ofMLS ground equipment includes an azimuth station to perform functions as indicated above. In addition to providing azimuth navigation guidance, the station transmits basic data,which consists of information associated directly with the operation of the landing system, as well as advisory data on the performance of the ground equipment.

Approach Azimuth Guidance

The azimuth station transmits MLS angle and data on one of 200 channels within the frequency range of 5031 to 5091 MHz. The equipment is normally located about 1,000 feetbeyond the stop end of the runway, but there is considerable flexibility in selecting sites. For example, for heliport operations the azimuth transmitter can be collocated withthe elevation transmitter. The azimuth coverage extends laterally at least 40° on either side of the runway centerline in a standard configuration, in elevation up to an angle of 15°and to at least 20,000 feet, and in range to at least 20 NM. MLS requires separate airborne equipment to receive and process the signals from what is normally installed in generalaviation aircraft today.

Microwave Landing System (MLS)

MLS

MLS employs 5GHz transmitters at the landing place which use passive electronically scanned arrays to send scanning beams towards approaching aircraft. An aircraft that enters the scanned volume uses a special receiver that calculates its position by measuring the arrival times of the beams. Compared to the existing ILS system, MLS had significant advantages. The antennas were much smaller, due to using a higher frequency signal. They also did not have to be placed at a specific point at the airport, and could "offset" their signals electronically. This made placement at the airports much simpler compared to the large ILS systems, which had to be placed at the ends of the runways and along the approach path.

Another advantage was that the MLS signals covered a very wide fan-shaped area off the end of the runway, allowing controllers to vector aircraft in from a variety of directions or guide aircraft along a segmented approach. In comparison, ILS required the aircraft to fly down a single straight line, requiring controllers to distribute planes along that line. MLS allowed aircraft to approach from whatever direction they were already flying in, as opposed to flying to a parking orbit before "capturing" the ILS signal. This was particularly interesting to larger airports, as it potentially allowed the aircraft to be separated horizontally until much closer to the airport.

MLS

Operational FunctionsThe system may be divided into five functions: Approach azimuth, Back azimuth, Approach elevation, Range and Data communications.

Approach azimuth guidance The azimuth station transmits MLS angle and data on one of 200 channels within the frequency range of 5031 to 5091 MHz and is normally located about 1,000 feet (300 m) beyond the stop end of the runway, but there is considerable flexibility in selecting sites. For example, for heliport operations the azimuth transmitter can be collocated with the elevation transmitter.The azimuth coverage extends: Laterally, at least 40 degrees on either side of the runway centerline in a standard configuration. In elevation, up to an angle of 15 degrees and to at least 20,000 feet (6 km), and in range, to at least 20 nautical miles (37 km)

MLS

Elevation guidance

The elevation station transmits signals on the same frequency as the azimuth station. A single frequency is time-shared between angle and data functions and is normally located about 400 feet from the side of the runway between runway threshold and the touchdown zone. Elevation coverage is provided in the same airspace as the azimuth guidance signals: In elevation, to at least +15 degrees; Laterally, to fill the Azimuth lateral coverage and in range, to at least 20 nautical miles (37 km).

MLS

Range guidance

The MLS Precision Distance Measuring Equipment (DME/P) functions the same as the navigation DME, but there are some technical differences. The beacon transponder operates in the frequency band 962 to 1105 MHz and responds to an aircraft interrogator. The MLS DME/P accuracy is improved to be consistent with the accuracy provided by the MLS azimuth and elevation stations.A DME/P channel is paired with the azimuth and elevation channel. A complete listing of the 200 paired channels of the DME/P with the angle functions is contained in FAA Standard 022 (MLS Interoperability and Performance Requirements).The DME/N or DME/P is an integral part of the MLS and is installed at all MLS facilities unless a waiver is obtained. This occurs infrequently and only at outlying, low density airports where marker beacons or compass locators are already in place.

Data communications

The data transmission can include both the basic and auxiliary data words. All MLS facilities transmit basic data. Where needed, auxiliary data can be transmitted. MLS data are transmitted throughout the azimuth (and back azimuth when provided) coverage sectors. Representative data include: Station identification, Exact locations of azimuth, elevation and DME/P stations (for MLS receiver processing functions), Ground equipment performance level; and DME/P channel and status.

Microwave Landing System (MLS)

Microwave Landing System (MLS)

An MLS azimuth guidance station with rectangular azimuth scanning antenna with DME antenna at left.

An MLS elevation guidance station

Required Navigation Performance

RNP is a navigation system that provides a specified level of accuracy defined by a lateral area of confined airspace in which an RNP-certified aircraft operates. The continuing

growth of aviation places increasing demands on airspace capacity and emphasizes the need for the best use of the available airspace. These factors, along with the accuracy of

modern aviation navigation systems and the requirement for increased operational efficiency in terms of direct routings and track-keeping accuracy, have resulted in the concept

of required navigation performance—a statement of the navigation performance accuracy necessary for operation within a defined airspace. RNP can include both performance

and functional requirements, and is indicated by the RNP type. These standards are intended for designers, manufacturers, and installers of avionics equipment, as well as service providers and users of these systems for global operations. The minimum aviation system performance specification (MASPS) provides guidance for the development of airspace and operational procedures needed to obtain the benefits of improved navigation capability.

The RNP type defines the total system error (TSE) that is allowed in lateral and longitudinal dimensions within a particular airspace. The TSE, which takes account of navigation system errors (NSE), computation errors, display errors and flight technical errors (FTE), must not exceed the specified RNP value for 95 percent of the flight time on any part of any single flight.

Microwave Landing System (MLS)

RNP combines the accuracy standards laid out in the ICAO Manual (Doc 9613) with specificaccuracy requirements, as well as functional and performance standards, for the RNAV

system to realize a system that can meet future air traffic management requirements. The

functional criteria for RNP address the need for the flight paths of participating aircraft to be both predictable and repeatable to the declared levels of accuracy. More information on RNP is contained in subsequent chapters.

The term RNP is also applied as a descriptor for airspace, routes, and procedures (including departures, arrivals, and IAPs). The descriptor can apply to a unique approach procedure or to a large region of airspace. RNP applies to navigation performance within a designated airspace, and includes the capability of both the available infrastructure (navigation aids) and the aircraft. RNP type is used to specify navigation requirements for the airspace. The following are ICAO RNP Types: RNP-1.0, RNP-4.0, RNP-5.0, and RNP-10.0. The required performance is obtained through a combination of aircraft capability and the level of service provided by the corresponding navigation infrastructure. From a broad perspective:

Aircraft Capability + Level of Service = Access

In this context, aircraft capability refers to the airworthiness certification and operational approval elements (including avionics, maintenance, database, human factors, pilot

procedures, training, and other issues). The level of service element refers to the NAS infrastructure, including published routes, signal-in-space performance and availability, and air traffic management.

Microwave Landing System (MLS)

When considered collectively, these elements result in providing access. Access provides the desired benefit (airspace, procedures, routes of flight, etc.).

RNP levels are actual distances from the centerline of the flight path, which must be maintained for aircraft and obstacle separation. Although additional FAA-recognized RNP

levels may be used for specific operations, the United States currently supports three standard RNP levels:

• RNP 0.3 – Approach• RNP 1.0 – Departure, Terminal• RNP 2.0 – En route

RNP 0.3 represents a distance of 0.3 NM either side of a specified flight path centerline. The specific performance that is required on the final approach segment of an instrument approach is an example of this RNP level. At the present time, a 0.3 RNP level is the lowest level used in normal RNAV operations. Specific airlines, using special procedures, are approved to use RNP levels lower than RNP 0.3, but those levels are used only in accordance with their approved operations specifications (OpsSpecs). For aircraft equipment to qualify for a specific RNP type, it must maintain navigational accuracy at least 95 percent of the total flight time.

Microwave Landing System (MLS)

Microwave Landing System (MLS)-RNP

FMS

A computer system that forms an integrated, full-flight communications and information management system that provides automatic navigation, guidance, communications, and fuel management computation. The system aids crews by automating many routine tasks and manual computations and by providing them with useful information on managing a flight path from origin to destination. In flight, the pilot can couple the flight management system with an autopilot that allows the system to fly the aircraft and provide guidance via integrated roll-and-pitch commands. The system’s position accuracy is constantly updated using conventional navigation aids. The system ensures that the most appropriate aids are selected automatically during the information-update cycle. Data are entered into the system using an alphanumeric keypad, and they are displayed on a cockpit-display unit.

FMS

A computer that is the heart of a flight management system, providing a centralized control for navigation and performance management. It obtains data from various navigational systems both ground based and on board aircraft. The system’s position accuracy is constantly updated using conventional navigation aids. The complete flight plan is loaded into the computer before the flight. The computer calculates air position, fuel consumption, aircraft position, and expected time of arrival and aids crews in managing the flight from origin to destination.

FMS

A flight management system (FMS) is a fundamental part of a modern aircraft's avionics. A FMS is a specialized computer system that automates a wide variety of in-flight tasks, reducing the workload on the flight crew to the point that modern aircraft no longer carry flight engineers or navigators. A primary function is in-flight management of the flight plan. Using various sensors (such as GPS and INS) to determine the aircraft's position, the FMS can guide the aircraft's autopilot along the flight plan. From the cockpit, the FMS is normally controlled through a Control Display Unit (CDU) which incorporates a small screen and keyboard. The FMS sends the flight plan for display on the EFIS, Navigation Display (ND) or MultiFunction Display (MFD).

Navigation database

All FMS contain a navigation database. The navigation database contains the elements from which the flight plan is constructed. These are defined via the ARINC 424 standard. The navigation database (NDB) is normally updated every 28 days, in order to ensure that its contents are current. Each FMS contains only a subset of the ARINC data, relevant to the capabilities of the FMS.The NDB contains all of the information required for building a flight plan and information relevant to it. These include:

• Waypoints, • Airways (highways in the sky)

FMS

These include• Radio navigation aids including distance measuring equipment (DME), VHF omnidirectional range (VOR), and non-directional beacons (NDBs) • Airports • Runways • Standard instrument departure (SID) • Standard terminal arrival (STAR) • Holding patterns • And a variety of related and often installation-specific information

IFR LETENJE

Flight plans are documents filed by pilots or a Flight Dispatcher with the local Civil Aviation Authority (e.g. FAA in the USA) prior to departure. They generally include basic information such as departure and arrival points, estimated time en route, alternate airports in case of bad weather, type of flight (whether instrument flight rules or visual flight rules), pilot's name and number of people on board. In most countries, flight plans are required for flights under IFR. Under VFR, they are optional unless crossing national borders, however they are highly recommended, especially when flying over inhospitable areas, such as water, as they provide a way of alerting rescuers if the flight is overdue.For IFR flights, flight plans are used by air traffic control to initiate tracking and routing services. For VFR flights, their only purpose is to provide needed information should search and rescue operations be required, or for use by air traffic control when flying in a "Special Flight Rules Area".

Routing Types

Aircraft routing types used in flight planning are: Airway, Navaid and Direct. A route may be composed of segments of different routing types. For example, a route from Chicago to Rome may include Airway routing over the U.S. and Europe, but Direct routing over the Atlantic Ocean.

IFR LETENJE

Airway

Airway routing occurs along pre-defined pathways called Airways. Airways can be thought of as three-dimensional highways for aircraft. In most land areas of the world, aircraft are required to fly airways between the departure and destination airports. The rules governing airway routing cover altitude, airspeed, and requirements for entering and leaving the airway ( SIDs and STARs). Most airways are eight nautical miles (14 kilometers) wide, and the airway flight levels keep aircraft separated by at least 500 vertical feet from aircraft on the flight level above and below. Airways usually intersect at Navaids, which designate the allowed points for changing from one airway to another. Airways have names consisting of one or more letters followed by one or more digits (e.g., V484 or UA419).The airway structure is divided into high and low altitudes. The low altitude airways in the U.S. which can be navigated using VOR Navaids have names that start with the letter V, and are therefore called Victor Airways. They cover altitudes from approximately 1200 feet above ground level (AGL) to 18,000 feet (5,486 m) above mean sea level (MSL). The high altitude airways in the U.S. all have names that start with the letter J, and are called Jet Routes. These run from 18,000 feet (5,486 m) to 35,000 feet (10,668 m). The altitude separating the low and high airway structures varies from country to country. For example, it is 19,500 feet (5,944 m) in Switzerland, and 25,500 feet (7,772 m) in Egypt.

IFR LETENJE

Navaid

Navaid routing occurs between Navaids (short for Navigational Aids,) which are not always connected by airways. Navaid routing is typically only allowed in the continental U.S. If a flight plan specifies Navaid routing between two Navaids which are connected via an airway, the rules for that particular airway must be followed as if the aircraft was flying Airway routing between those two Navaids. Allowable altitudes are covered in Flight Levels.

Direct

Direct routing occurs when one or both of the route segment endpoints are at a latitude/longitude which is not located at a Navaid. Some flight planning organizations specify that checkpoints generated for a Direct route be a limited distance apart, or limited by time to fly between the checkpoints (i.e. direct checkpoints could be farther apart for a fast aircraft than for a slow one).

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SIDs and STARs

SIDs and STARs are procedures and checkpoints used to enter and leave the airway system by aircraft operating on IFR flight plans. There is a defined transition point at which an airway and a SID or STAR intersect.A SID, or Standard Instrument Departure, defines a pathway out of an airport and onto the airway structure. A SID is sometimes called a Departure Procedure (DP). SIDs are unique to the associated airport.A STAR, or Standard Terminal Arrival Route, ('Standard Instrument Arrival' in the UK) defines a pathway into an airport from the airway structure. STARs can be associated with more than one arrival airport, which can occur when two or more airports are in close proximity (e.g., San Francisco and San Jose).

Special use airspace

In general, flight planners are expected to avoid areas called Special Use Airspace (SUA) when planning a flight. In the United States, there are several types of SUA, including Restricted, Warning, Prohibited, Alert, and Military Operations Area (MOA). Examples of Special Use Airspace include a region around the White House in Washington, D.C., and the country of Cuba. Government and military aircraft may have different requirements for particular SUA areas, or may be able to acquire special clearances to traverse through these areas.

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Flight levels

Flight levels (FL) are used by air traffic controllers to simplify the vertical separation of aircraft and one exists every 1000 feet relative to an agreed pressure level. Above a transitional altitude, which varies from country to country, the worldwide arbitrary pressure datum of 1013.25 millibar or the equivalent setting of 29.921 inches of mercury is entered into the altimeter and altitude is then referred to as a flight level. The altimeter reading is converted to a flight level by removing the trailing two zeros: for example, 29000 feet becomes FL290 and 25500 feet is FL255. When the pressure at sea level is by chance the international standard then the flight level is also the altitude. To avoid confusion, below the transition altitude, height is referred to as altitude, for example 'climb flight level 250' or 'descend altitude...'Airways have a set of associated standardized flight levels (sometimes called the "flight model") which must be used when on the airway. On a bi-directional airway, each direction has its own set of flight levels. A valid flight plan must include a legal flight level at which the aircraft will travel the airway. A change in airway may require a change in flight level.In the USA, for eastbound (heading 0–179 degrees) IFR flights, the flight plan must list an "odd" flight level in 2000 foot increments starting at FL190 (i.e., FL190, FL210, FL230, etc.); Westbound (heading 180–359 degrees) IFR flights must list an "even" flight level in 2000 foot increments starting at FL180 (i.e., FL180, FL200, FL220, etc.). However, Air Traffic Control (ATC) may assign any flight level at any time if traffic situations merit a change in altitude.Aircraft efficiency increases with height. Burning fuel decreases the weight of an aircraft which may then choose to increase its flight level to further improve fuel consumption. For example an aircraft may be able to reach FL290 early in a flight, but step climb to FL370 later in the route after weight has decreased due to fuel burn off.

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Reduced Vertical Separation Minima or Minimum (RVSM) is an aviation term used to describe the reduction of the standard vertical separation required between aircraft flying at levels between FL290 (29,000 ft.) and FL410 (41,000 ft.) from 2,000 feet to 1,000 feet (or between 8,900 metres and 12,500 metres from 600 metres to 300 metres in China). This therefore increases the number of aircraft that can safely fly in a particular volume of airspace.Historically, standard vertical separation was 1,000 feet from the surface to FL290, 2,000 feet from FL290 to FL410 and 4,000 feet above this. This was because the accuracy of the pressure altimeter (used to determine altitude) decreases with height. Over time, Air data computers (ADCs) combined with altimeters have become more accurate and autopilots more adept at maintaining a set level, therefore it became apparent that for many modern aircraft, the 2,000 foot separation was too cautious. It was therefore proposed by ICAO that this be reduced to 1,000 feet.Between 1997 and 2005 RVSM was implemented in all of Europe, North Africa, Southeast Asia and North America, South America, and over the North Atlantic, South Atlantic, and Pacific Oceans. The North Atlantic implemented initially in March 1997 at flight levels 330 through 370. The entire western hemisphere implemented RVSM FL290-FL410 on January 20, 2005. Africa implemented it on September 25, 2008.Only aircraft with specially certified altimeters and autopilots may fly in RVSM airspace, otherwise the aircraft must fly lower or higher than the airspace, or seek special exemption from the requirements. Additionally, aircraft operators (airlines or corporate operators) must receive specific approval from the aircraft's state of registry in order to conduct operations in RVSM airspace. Non RVSM approved aircraft may transit through RVSM airspace provided they are given continuous climb throughout the designated airspace, and 2,000ft vertical separation is provided at all times between the non-RVSM flight, and all others for the duration of the climb/descent.Critics of the change are concerned that by reducing the space between aircraft, RVSM may increase the number of mid-air collisions and conflicts. In the ten years since RVSM was first implemented not one collision has been attributed to RVSM. In the US this program was known as the Domestic Reduced Vertical Separation Minimum (DRVSM)..

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Alternate airportsPart of flight planning often involves the identification of one or more airports which can be flown to in case of unexpected conditions (such as weather) at the destination airport. The planning process must be careful to include only alternate airports which can be reached with the anticipated fuel load and total aircraft weight and that have capabilities necessary to handle the type of aircraft being flown.FuelAircraft manufacturers are responsible for generating flight performance data which flight planners use to estimate fuel needs for a particular flight. The fuel burn rate is based on specific throttle settings for climbing and cruising. The planner uses the projected weather and aircraft weight as inputs to the flight performance data to estimate the necessary fuel to reach the destination. The fuel burn is usually given as the weight of the fuel (usually pounds or kilograms) instead of the volume (such as gallons or litres) because aircraft weight is critical.In addition to standard fuel needs, some organizations require that a flight plan include reserve fuel if certain conditions are met. For example, an over-water flight of longer than a specific duration may require the flight plan to include reserve fuel. The reserve fuel may be planned as extra which is left over on the aircraft at the destination, or it may be assumed to be burned during flight (perhaps due to unaccounted for differences between the actual aircraft and the flight performance data).In case of an in-flight emergency it may be necessary to determine whether it is quicker to divert to the alternate airfield or continue to the destination. This can be calculated according to the formula (known as the Vir Narain formula) as follows:

C = D O secθ / 2Awhere C is the distance from the Critical Point (equitime point) to the destination, D the distance between the destination and the alternate airfield, O is the groundspeed, A is the airspeed, θ = Φ +/- d (where Φ is the angle between the track to the destination and the track from the destination to the alternate airfield), and d is the drift (plus when the drift and the alternate airfield are on the opposite sides of the track, and minus when they are on the same side).

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Flight plan timelineFlight plans may be submitted before departure or even after the aircraft is in the air. However flight plans may be submitted up to 24 hours in advance either by voice or by data link; though they are usually filled out or submitted just several hours before departure. The minimum recommended time is 1 hour before departure for domestic flights, and up to three hours before international flights. This time depends on the country the aircraft is flying out of.

Other Flight Planning ConsiderationsHolding over the destination or alternate airports is a required part of some flight plans. Holding (circling in a pattern designated by the airport control tower) may be necessary if unexpected weather or congestion occurs at the airport. If the flight plan calls for hold planning, the additional fuel and hold time should appear on the flight plan.Organized Tracks are a series of paths similar to airways which cross ocean areas. Some organized track systems are fixed and appear on navigational charts (e.g., the NOPAC tracks over the Northern Pacific Ocean). Others change on a daily basis depending on weather and other factors and therefore cannot appear on printed charts (e.g., the North Atlantic Tracks (NAT) over the Atlantic Ocean).

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Description of flight plan blocks Type: Type of flight plan. Flights may be VFR, IFR, DVFR, or a combination of types, termed composite. Aircraft Identification: The registration of the aircraft, usually the flight or tail number. Aircraft Type/Special Equipment: The type of aircraft and how it's equipped. For example, a Mitsubishi Mu-2 equipped with an altitude reporting transponder and GPS would use MU2/G. Equipment codes may be found in the FAA Airman's Information Manual. True airspeed in knots: The planned cruise true airspeed of the aircraft in knots. Departure Point: Usually the identifier of the airport from which the aircraft is departing. Departure Time: Proposed and actual times of departure. Times are Universal Time Coordinated. Cruising Altitude: The planned cruising altitude or flight level. Route: Proposed route of flight. The route can be made up of airways, intersections, navaids, or possibly direct. Destination: Point of intended landing. Typically the identifier of the destination airport. Estimated Time Enroute: Planned elapsed time between departure and arrival at the destination. Remarks: Any information the PIC believes is necessary to be provided to ATC. One common remark is "SSNO", which means the PIC is unable or unwilling to accept a SID or STAR on an IFR flight. Fuel on Board: The amount of fuel on board the aircraft, in hours and minutes of flight time. Alternate Airports: Airports of intended landing as an alternate of the destination airport. May be required for an IFR flight plan if poor weather is forecast at the planned destination. Pilot's Information: Contact information of the pilot for search and rescue purposes. Number Onboard: Total number of people on board the aircraft. Color of Aircraft: The color helps identify the aircraft to search and rescue personnel. Contact Information at Destination: Having a means of contacting the pilot is useful for tracking down an aircraft that has failed to close its flight plan and is possibly overdue or in distress.

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In air traffic control, separation is the name for the concept of keeping an aircraft in a minimum distance from another aircraft to reduce the risk of those aircraft colliding, as well as prevent accidents due to wake turbulence.Air traffic controllers apply rules, known as separation minima to do this. Pairs of aircraft to which these rules have been successfully applied are said to be separated: the risk of these aircraft colliding is therefore remote. If separation is lost between two aircraft, they are said to be in a conflict.When an aircraft passes behind or follows another aircraft, wake turbulence minima are applied due to the effect of the wingtip vortices of the preceding aircraft on the following aircraft. These minima vary depending on the relative size of the two aircraft. This is particularly acute on final approach with a smaller aircraft following larger aircraft.

Which aircraft need separating?It is a common misconception that air traffic controllers keep all aircraft separated. Whether aircraft actually need separating depends upon the class of airspace in which the aircraft are flying, and the flight rules under which the pilot is operating the aircraft. As stated by the U.S. FAA, The pilot has the ultimate responsibility for ensuring appropriate separations and positioning of the aircraft in the terminal area to avoid the wake turbulence created by a preceding aircraft.There are three sets of flight rules under which an aircraft can be flown:Visual Flight Rules (VFR) Special Visual Flight Rules (SVFR) Instrument Flight Rules (IFR)

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Public transport flights are almost exclusively operated under IFR, as this set of rules allows flight in regions of low visibility (e.g. cloud). On the other hand a large amount of private flying in light aircraft is done under VFR since this requires a lower level of flying skill on the part of the pilot, and meteorological conditions in which a pilot can see and avoid other aircraft. As its name suggests, SVFR is a special infrequently-used set of rules. For the purposes of separation, controllers consider SVFR to be the same as IFR.Airspace exists in seven classes, A to G, in decreasing order of air traffic control regulation. Classes A to E are controlled airspace and classes F and G are uncontrolled airspace. At one end of the scale in classes A and B airspace, all aircraft must be separated from each other. At the other end of the scale in class G airspace there is no requirement for any aircraft to be separated from each other. In the intermediate classes some aircraft are separated from each other depending on the flight rules under which the aircraft are operating. For example in class D airspace, IFR aircraft are separated from other IFR aircraft, but not from VFR aircraft, nor are VFR aircraft separated from each other.

Vertical separation

Between the surface and an altitude of 29,000 feet (8,800 m), no aircraft should come closer vertically than 1,000 feet or 300 metres (in those countries that express altitude in metres), unless some form of horizontal separation is provided. Above 29,000 feet (8,800 m) no aircraft shall come closer than 2,000 feet (or 600 m), except in airspace where Reduced Vertical Separation Minima (RVSM) can be applied.

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Horizontal separationIf any two aircraft are separated by less than the vertical separation minimum, then some form of horizontal separation must exist.

Procedural separationProcedural separation is separation based upon the position of the aircraft, based upon reports made by the pilots over the radio. It therefore does not necessarily require the use of radar to provide air traffic control using procedural separation minima. In procedural control, any period during which two aircraft are not vertically separated is said to be "level change". In some cases, procedural separation minima are provided for use with radar assistance, however it is important not to get this mixed up with radar separation as in the former case the radar need not necessarily be certified for use for radar separation purposes, the separation is still procedural.

Lateral separationLateral separation minima are usually based upon the position of the aircraft as derived visually, from dead reckoning or internal navigation sources, or from radio navigation aids ('beacons').In the case of beacons, to be separated, the aircraft must be a certain distance from the beacon (measured by time or by DME) and their tracks to or from the beacon must diverge by a minimum angle.Other lateral separation may be defined by the geography of pre-determined routes, for example the North Atlantic Track system.

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Longitudinal separation

If two aircraft are not laterally separated, and are following tracks within 45 degrees of each other (or the reciprocal), then they are said to be following the same route and some form of longitudinal separation must exist.Longitudinal separation can be based upon time or distance as measure by DME. The golden rule is the 15 minute rule: no two aircraft following the same route must come within 15 minutes flying time of each other. In areas with good navaid cover this reduces to 10 minutes; if the preceding aircraft is faster than the following one then this can be reduced further depending of the difference in speed.Aircraft whose tracks bisect at more than 45 degrees are said to be crossing, in this case longitudinal separation cannot be applied as it will not be very long before lateral separation will exist again.

Radar separation

Radar separation is applied by a controller observing that the radar returns from the two aircraft are a certain minimum horizontal distance away from each other, as observed on a suitably calibrated radar system. The actual distance used varies: 5 nmi (9 km) is common in en route airspace, 3 NM is common in terminal airspace at lower levels. On occasion 10 NM may be used, especially at long range or in regions of less reliable radar cover.By US FAA Rules, when an aircraft is:

1. Less than 40 miles from the [radar] antenna, horizontal separtion is 3 miles from obstructions or other aircraft.

2. 40 miles or more from the [radar] antenna, horizontal separation is 5 miles from obstructions or other aircraft.

3. Terminal Area For single sensor ASR-9 with Mode S, when less than 60 miles from the antenna, horizontal separation is 3 miles from other aircraft.

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Reduced separation

In certain special cases, controllers may reduce separation below the usually required minima in the vicinity of an aerodrome.

A erodrome or "Tower" controllers work in tall towers with large windows allowing them, in good weather, to see the aircraft flying in the vicinity of the aerodrome, unless the aircraft is not in sight from the tower (i.e. a helicopter departing from a ramp area). Also, aircraft in the vicinity of an aerodrome tend to be flying at lower speeds. Therefore, if the aerodrome controller can see both aircraft, or both aircraft report that they can see each other, or a following aircraft reports that it can see the preceding one, controllers may reduce the standard separation to whatever is adequate to prevent a collision.

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ConflictsA conflict is an event in which two or more aircraft experience a loss of minimum separation. This does not in itself suggest that the aircraft are at any risk of collision. However, the separation minima are set for risk mitigation and therefore it is central to a controller's job to prevent this situation from occurring. Conflicts are detected by data assistants, who report them to the actual controllers; the data assistants suggest how to solve the conflict, but the controller is not obligated to follow the suggested instructions. A conflict occurs when the distance between aircraft in flight violates a defining criterion, usually considered as 5 nautical miles (9 km) of horizontal and/or 1000 feet of vertical separation. These distances define an aircraft's protected zone, a volume of airspace surrounding the aircraft which should not be infringed upon by any another aircraft.Local conflictA local conflict occurs if two or more aircraft pass a certain given point (in nearly all cases a certain town). A local conflict occurs, if at least one of the following conditions are met:The distance in time is 4 minutes or less, and The distance in space is 30 flight units or less.Opposite conflictAn opposite conflict occurs if two aircraft are flying towards each other from opposing directions. Looking at the information on the flight progress strips, a controller can detect an opposite conflict by checking:If one aircraft is flying from city A to city B and another from city B to city A, If comparisons of the temporal distance of the first plane over city A with that of the second plane over city B and that of the second plane over city A with the first plane over city B lead to a separation of 4 minutes or less at any time during their flights, or If comparisons of the topical altitude of the first plane over city A with that of the second plane over city B and then the altitude of the second plane over city A with that of the first plane over city B give a separation of 30 flight units or less at any time during their flights.

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Doc 4444ATM/501Procedures forAir Navigation Services

CHAPTER 5. SEPARATION METHODSAND MINIMA

The lateral separation points are calculated by the formula: R = Sy / sin θwhere:Sy = the lateral distance between the tracks equal to the lateral separation minimum;R = the distance of the lateral separation point from the intersection;

θ = the angle between tracks.

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RADAR

Radar "radio detection and ranging," is a sensor; its purpose is to provide estimates of certain characteristics of its surroundings of interest to a user, most commonly the presence, position, and motion of such objects as aircraft, ships, or other vehicles in its vicinity. In other uses, radars provide information about the Earth's surface (or that of other astronomical bodies) or about meteorological conditions. To provide the user with a full range of sensor capability, radars are often used in combinations or with other elements of more complete systems.

Radar operates by transmitting electromagnetic energy into the surroundings and detecting energy reflected by objects. If a narrow beam of this energy is transmitted by the directive antenna, the direction from which reflections come and hence the bearing of the object may be estimated. The distance to the reflecting object is estimated by measuring the period between the transmission of the radar pulse and reception of the echo. In most radar applications this period will be very short since electromagnetic energy travels with the velocity of light.Radars intended principally to determine the presence and position of reflecting targets in a region around the radar are called search radars. Other radars examine further the targets detected: examples are height finders with antennas that scan vertically in the direction of an assigned target, and tracking radars that are aimed continuously at an assigned target to obtain great accuracy in estimating target motion. In some modern radars, these search and track functions are combined, usually with some computer control. Surveillance radar connotes operation of this sort, somewhat more than just search alone. There are also very complex and versatile radars with considerable computer control, with which many functions are performed and which are therefore called multifunction radars. Very accurate tracking radars intended for use at missile test sites or similar test ranges are called instrumentation radars. Radars

designed to detect clouds and precipitation are called meteorological or weather radars.

RADAR

Radars composed of four principal parts: the transmitter, antenna, receiver, and display.

RADAR

The transmitter provides the rf signal in sufficient strength (power) for the radar sensitivity desired and sends it to the antenna, which causes the signal to be radiated into space in a desired direction. The signal propagates (radiates) in space, and some of it is intercepted by reflecting bodies. These reflections, in part at least, are radiated back to the antenna. The antenna collects them and routes all such received signals to the receiver, where they are amplified and detected. The presence of an echo of the transmitted signal in the received signal reveals the presence of a target. The echo is indicated by a sudden rise in the output of the detector, which produces a voltage (video) proportional to the sum of the rf signals being received and the rf noise inherent in the receiver itself. The time between the transmission and the receipt of the echo discloses the range to the target. The direction or bearing of the target is disclosed by the direction the antenna is pointing when an echo is received.A duplexer permits the same antenna to be used on both transmit and receive, and is equipped with protective devices to block the very strong transmit signal from going to the sensitive receiver and damaging it. The antenna forms a beam, usually quite directive, and, in the search example, rotates throughout the region to be searched. The radar reflections are among the signals received by the antenna in the period between transmissions. Most search radars have a pulse repetition frequency (prf), antenna beam-width, and rotation rate such that several pulses are transmitted (perhaps 20 to 40) while the antenna scans past a target. This allows a buildup of the echo being received. Most radars are equipped with low-noise rf preamplifiers to improve sensitivity. The signal is then “mixed” with (multiplied by) a local oscillator signal to produce a convenient intermediate-frequency (i-f) signal, commonly at 30 or 60 MHz; the same principle is used in all heterodyne radio receivers. The local oscillator signal, kept offset from the transmit frequency by precisely this intermediate frequency, is supplied by the transmitter oscillators during reception. After other significant signal processing in the i-f circuitry (of a digital nature in many newer radars), a detector produces a video signal, a voltage proportional to the strength of the processed i-f signal. This video can be applied to a cathode-ray-tube (CRT) display so as to form a proportionately bright spot (a blip), which could be judged to originate from a target echo. However, increasingly radars use artificial computerlike displays based on computer analysis of the video. Automatic detection and automatic tracking (based on a sequence of dwells) are typical of such data processing, reports being displayed for radar operator management and also made instantly available to the user system.

RADAR

One way to measure the distance to an object is to transmit a short pulse of radio signal (electromagnetic radiation), and measure the time it takes for the reflection to return. The distance is one-half the product of the round trip time (because the signal has to travel to the target and then back to the receiver) and the speed of the signal. Since radio waves travel at the speed of light (186,000 miles per second or 300,000,000 meters per second), accurate distance measurement requires high-performance electronics.In most cases, the receiver does not detect the return while the signal is being transmitted. Through the use of a device called a duplexer, the radar switches between transmitting and receiving at a predetermined rate. The minimum range is calculated by measuring the length of the pulse multiplied by the speed of light, divided by two. In order to detect closer targets one must use a shorter pulse

length.

Pulse radar Continuous wave (CW) radar

RADAR

Speed measurementSpeed is the change in distance to an object with respect to time. Thus the existing system for measuring distance, combined with a memory capacity to see where the target last was, is enough to measure speed. At one time the memory consisted of a user making grease-pencil marks on the radar screen, and then calculating the speed using a slide rule. Modern radar systems perform the equivalent operation faster and more accurately using computers.However, if the transmitter's output is coherent (phase synchronized), there is another effect that can be used to make almost instant speed measurements (no memory is required), known as the Doppler effect. Most modern radar systems use this principle in the pulse-doppler radar system. Return signals from targets are shifted away from this base frequency via the Doppler effect enabling the calculation of the speed of the object relative to the radar. The Doppler effect is only able to determine the relative speed of the target along the line of sight from the radar to the target. Any component of target velocity perpendicular to the line of sight cannot be determined by using the Doppler effect alone, but it can be determined by tracking the target's azimuth over time.

Doppler effect, change in the wavelength (or frequency) of energy in the form of waves, e.g., sound or light, as a result of motion of either the source or the receiver of the waves; the effect is named for the Austrian scientist Christian Doppler, who demonstrated the effect for sound. If the source of the waves and the receiver are approaching each other (because of the motion of either or both), the frequency of the waves will increase and the wavelength will be shortened-sounds will become higher pitched and light will appear bluer. If the sender and receiver are moving apart, sounds will become lower pitched and light will appear redder. A common example is the sudden drop in the pitch of a train whistle as the train passes a stationary listener. The Doppler effect in reflected radio waves is employed in radar to

sense the velocity of the object under surveillance.

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In aviation a ground-controlled approach (GCA), is a type of service provided by air-traffic controllers whereby they guide aircraft to a safe landing in adverse weather conditions based on radar images. Most commonly a GCA uses information from either a Precision Approach Radar (PAR, for precision approaches with vertical, glide path guidance) or an Airport Surveillance Radar (ASR, providing a non-precision Surveillance Radar Approach with no glide path guidance). Technically, the term GCA applies specifically to the precision radar approach with glide path guidance.

OverviewGround-controlled approach is the oldest air traffic technique to fully implement radar to service a plane - it was largely used during the Berlin airlift in 1948-49. It requires close communication between ground-based air traffic controllers and pilots in approaching aircraft. Only one pilot is guided at a time (max. 2 under certain circumstances). The controllers monitor dedicated precision approach radar systems, to determine the precise course and altitude of approaching aircraft. The controllers then provide verbal instructions by radio to the pilots to guide them to a landing. The instructions include both descent rate (glide path) and heading (course) corrections necessary to follow the correct approach path.

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By following both tracks a landing aircraft will arrive precisely over the runway's touchdown zone. Controllers issue position information and/or correction for both of them at least every five seconds. The guidance is stopped over the approximate touchdown point, but to continue the approach to a landing, pilots must be able to see the runway environment before reaching the published "decision height," usually 200-400 ft above the runway touchdown zone and 1/4 to 3/4 miles from the touchdown point (the published minimum visibility and decision height vary depending upon approach and runway lighting, obstacles in the approach corridor, type of aircraft, and other factors). Pilots of revenue flights periodically must demonstrate PAR approach proficiency, and GCA controllers must conduct a minimum number of such approaches in a year to maintain competency.

Because of their labor-intensive nature -- one GCA controller is normally required for each aircraft on final approach -- GCAs are no longer in widespread use at civilian airports. However, air traffic controllers at some locations in the United States are required to maintain currency in their use,.Global Positioning System (GPS) based approaches that provide both lateral and vertical guidance are coming into widespread use, with approach minima as good as, or nearly as good as, GCA or ILS. Modern ILS and GPS approaches eliminate the possibility of human error from the controller, and can serve many aircraft at the same time. The ground-controlled approach is useful when the approaching aircraft is not equipped with sophisticated navigation aids, and may also become a life saver when an aircraft's on-board navigation aids are inoperative, as long as one communication radio works. Sometimes the PAR-based ground-controlled approach is also requested by qualified pilots when they are dealing with an emergency on-board to lighten their workload, or to "back up" ILS or other approach guidance.

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A radar system located on an airfield for observation of the position of an aircraft with respect to an approach path, and specifically intended to provide guidance to the aircraft during its approach to the field; the system consists of a ground radar equipment which is alternately connected to two antenna systems; one antenna system sweeps a narrow beam over a 20° sector in the horizontal plane; the second sweeps a narrow beam over a 7° sector in the vertical plane; course correction is transmitted to the aircraft from the ground.

A tracking system that provides a ground control approach (GCA) air-traffic controller with a precise display of an aircraft's position relative to a runway final-approach course. To ensure absolute safety, precise information is displayed on a plan position indicator (PPI). This display provides the controller with aircraft position information for control of heading and rate of descent. To accomplish this and maintain the required precision for a final-approach aid, the display shows the aircraft position in relation to range, azimuth, and elevation. The information presented on the precision approach radar display allows an air-traffic controller to direct a pilot down along a runway approach course to a precision landing. Precision radar approaches are accomplished in most weather conditions and do not require any on-board avionics equipment, such as an instrument landing system (ILS).There are two ways to provide the required range, azimuth, and elevation information on the plan position indicator: use of two antennas, one scanning elevation and the other azimuth; and a single computer-controlled phased-array antenna that can provide pencil-beam tracking for both elevation and azimuth positions.

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Primary radar equipment used to determine the position of an aircraft during final approach, in terms of lateral and vertical deviations relative to a nominal approach path, and in range relative to touch down (ICAO). The system is basically a high-definition radar designed to accurately locate an airplane within 300 ft of the range, 10 ft of the elevation at a distance of one mile, and 20 ft laterally. This form of navigation assistance is termed a precision radar approach. PAR is one of the components of a GCA (ground-controlled approach); the other is an SRE (surveillance radar element) or an ASR (airport surveillance radar). With the help of this equipment, pilots can be “talked down” during the final stages of the approach to land. Normally, an aircraft will be handed over to a PAR controller by an SRE controller.

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Precision approach radar (PAR) is a type of radar guidance system designed to provide lateral and vertical guidance to an aircraft pilot for landing, until the landing threshold is reached. After the aircraft reaches the decision height (DH) or decision altitude (DA), guidance is advisory only. Controllers monitoring the PAR displays observe each aircraft's position and issue instructions to the pilot that keep the aircraft on course and glidepath during final approach. It is similar to an instrument landing system (ILS) but requires control instructions. One type of instrument approach that can make use of PAR is the ground-controlled approach (GCA). Air traffic controllers must transmit a minimum of every 5 seconds to the pilot their relation to the azimuth portion and, once intercepting the glidepath, their elevation. The approach is terminated when the aircraft touches down or the pilot reports airport in sight and that they "will proceed visually."

The upper portion of the display indicates elevation, the lower portion azimuth. Controllers must be able to interpret radar returns for the azimuth as a "top view" to inform them if the aircraft is left or right of course.

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Precision approach radars are most frequently used at military air traffic control facilities. Many of these facilities use the AN/FPN-63, AN/MPN, or AN/TPN-22. These radars can provide precision guidance to a distance of 10 to 20 miles. The OJ-333 Radar scope is the indicator which the air traffic controller uses to provide instructions to the pilots.

Local Area Augmentation System (LAAS) The augmentation to the global positioning system (GPS) to meet Cat I, Cat II, and CAT III precision approach accuracy, integrity, continuity, and availability requirements. The system is ground-based and comprises a ground reference station at or near an airport. The airborne system has only a top incorporate differential correction capability as well as a link with the ground reference station for receiving correctional data.

Local Area Augmentation System (LAAS) The Local Area Augmentation System (LAAS) is an all-weather aircraft landing system based on real-time differential correction of the GPS signal. Local reference receivers located around the airport send data to a central location at the airport. This data is used to formulate a correction message, which is then transmitted to users via a VHF Data Link. A receiver on an aircraft uses this information to correct GPS signals, which then provides a standard ILS-style display to use while flying a precision approach. The International Civil Aviation Organization (ICAO) calls this type of system a Ground Based Augmentation System (GBAS). The Local Area Augmentation System (LAAS) is designed to correct some of the errors inherent to GPS. One problem is the lack of a real-time, rapid-response monitoring system. Category I equipment will normally alert the user of the problem within ten seconds of detecting a problem. GPS has no such rapid-warning system. For example, if a satellite develops a clock problem, there is no way to rapidly warn the user not to use that satellite. WAAS, LAAS and other differential solutions fix this problem and provide GPS system integrity. Another problem is positional accuracy. Sources of error such as satellite clock drift or ionospheric delays can introduce several meters of error in an aircraft's position. These errors must be corrected in real time for a precision approach where there is little or no visibility.

Local Area Augmentation System (LAAS) OperationLocal reference receivers are located around an airport at precisely surveyed locations. The signal received from the GPS constellation is used to calculate the position of the LAAS ground station, which is then compared to its precisely surveyed position. This data is used to formulate a correction message which is transmitted to users via a VHF data link. A receiver on the aircraft uses this information to correct the GPS signals it receives. This information is used to create an ILS-type display for aircraft approach and landing purposes. Honeywell’s CAT I system provides precision approach service within a radius of 23 NM surrounding a single airport. LAAS mitigates GPS threats in the Local Area to a much greater accuracy than WAAS and therefore provides a higher level of service not attainable by WAAS. LAAS's VHF uplink signal is currently slated to share the frequency band from 108 MHz to 118 MHz with existing ILS localizer and VOR navigational aids. LAAS utilizes a Time Division Multiple Access (TDMA) technology as servicesin servicing the entire airport with a single frequency allocation. With future replacement of ILS, LAAS will reduce the congested VHF NAV band.AccuracyThe current Non-Fed LAAS is capable of achieving a Category I ILS accuracy of 16 m laterally and 4 m vertically.The goal of the LAAS program is to provide Category III ILS capability. The minimum accuracy for lateral and vertical errors of a Category III system are specified in RTCA DO-245A, Minimum Aviation System Performance Standards for Local Area Augmentation System (LAAS). Category III GBAS will allow aircraft to land with zero visibility utilizing 'autoland' systems

Wide Area Augmentation System (WAAS) The WAAS is a satellite navigation system consisting of the equipment and software that augment the GPS (global positioning system) Standard Positioning Service (SPS). The WAAS provides enhanced integrity, accuracy, availability, and continuity over and above the GPS and the SPS. The differential correction function provides the improved accuracy required for precision approaches. This augmentation of the GPS system will permit its use as a primary means of navigation for en route travel, nonprecision approaches, and CAT I approach capability at some airports.

Wide Area Augmentation System (WAAS) The Wide Area Augmentation System (WAAS) is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System (GPS), with the goal of improving its accuracy, integrity, and availability. Essentially, WAAS is intended to enable aircraft to rely on GPS for all phases of flight, including precision approaches to any airport within its coverage area.WAAS uses a network of ground-based reference stations, in North America and Hawaii, to measure small variations in the GPS satellites' signals in the western hemisphere. Measurements from the reference stations are routed to master stations, which queue the received Deviation Correction (DC) and send the correction messages to geostationary WAAS satellites in a timely manner (every 5 seconds or better). Those satellites broadcast the correction messages back to Earth, where WAAS-enabled GPS receivers use the corrections while computing their positions to improve accuracy.

The International Civil Aviation Organization (ICAO) calls this type of system a satellite-based augmentation system (SBAS). Europe and Asia are developing their own SBASs.

WAAS vs LAAS (GBAS)

Like the Wide Area Augmentation System (WAAS), LAAS relies on GPS for basic navigation signals. However, with WAAS, GPS-corrected navigation signals come from space, broadcast from WAAS geostationary satellites. With LAAS, the GPS-corrected navigation signal is broadcast from a LAAS VHF data broadcast transmitter at or near the airport. Although LAAS and WAAS will operate independently, LAAS will complement WAAS by providing GNSS Landing System (GLS) landing service for Category II/III precision approach operations. LAAS will also provide GLS Category-I capability at locations where WAAS service may not be available. Other differences between WAAS and LAAS include the manner in which the availability of the systems are computed, the manner in which avionics receive information on approach procedures, and the vertical alert limits (VAL) associated with each system.

The U.S. version of the Ground Based Augmentation System (GBAS) has traditionally been referred to as the Local Area Augmentation System (LAAS).  The worldwide community has adopted GBAS as the official term for this type of navigation system.  To coincide with international terminology, the FAA is also adopting the term GBAS to be consistent with the international community.

OPERACIJE U HITNIM SLUČAJEVIMA A Mayday situation is one in which a vessel, aircraft, vehicle, or person is in grave and imminent danger and requires immediate assistance. Examples of "grave and imminent danger" in which a Mayday call would be appropriate include fire, explosion or sinking.Mayday calls can be made on any frequency, and when a Mayday call is made no other radio traffic is permitted except to assist in the emergency. A Mayday call may only be made when life or craft is in imminent danger of death or destruction.Mayday calls are made by radio, such as a ship or aircraft's VHF radio. Although a Mayday call will be understood regardless of the radio frequency on which it is broadcast, first-line response organisations, such as the coastguard and air traffic control, monitor designated channels: marine MF on 2182 kHz; marine VHF radio channel 16 (156.8 MHz); and airband frequencies of 121.5 MHz and 243.0 MHz. A Mayday call is roughly equivalent of a morse code SOS, or a telephone call to the emergency services.

Making a hoax Mayday call is a criminal act in many countries because of the danger to the rescuers' lives that a search-and-rescue operation can create, the potential for real emergencies elsewhere, as well as the very high costs of such rescue efforts

A distress call (situation where the aircraft requires immediate assistance) is prefixed: MAYDAY, MAYDAY, MAYDAY.An urgency message (situation not requiring immediate assistance) is prefixed: PAN-PAN, PAN-PAN, PAN-PAN the (ICAO) definitions. NB the "nature of the emergency" is not the issue - but the assistance you require.

More informally, if things are under control, I can adhere to ATC expectations, then a Pan is a heads up to leave me alone and let me sort things out, and I'll let you know when I can what I want from you (ATC). If I cannot comply with ATC expectations/clearance e.g. Emergency Descent, or do need immediate assistance then a Mayday it is.

OPERACIJE U HITNIM SLUČAJEVIMA Fire

Provided are hand fire extinguishers for use in crew, passenger, and cargo compartments, and galleys. The type of extinguisher must be suitable for the kinds of fires likely to occur in the compartment where the intended use of the extinguisher is and, for personnel compartments, to minimise the hazard of toxic gas concentration.

At least one hand fire extinguisher, containing Halon 1211 (bromochlorodifluromethane, CBrCIFZ), or equivalent as the extinguishing agent, must be conveniently located on the flight deck for use by the flight crew.

At least one hand fire extinguisher must be located in, or readily accessible for use in, each galley not located on the main passenger deck.

At least one readily accessible hand fire extinguisher must be available for use in each Class A or Class B cargo or baggage compartment and in each Class E cargo compartment that is accessible to crewmembers in flight.

OPERACIJE U HITNIM SLUČAJEVIMA

OPERACIJE U HITNIM SLUČAJEVIMA

SMOKESmoke in any form at any location is hazardous to life, and when airborne it is particularlydangerous. Smoke reduces the absorption of oxygen into the lungs. In extreme cases this leadsto asphyxiation and death. It also causes panic which can lead to irrational behaviour. Othereffects include stimulation of the mucus membranes, irritation of the lungs, and obviously,reduced vision. On the flight deck, smoke distracts the pilots from their duty and one or both must take action with the necessary check list to identify the source of the smoke and stop it.To reduce or negate the physiological effects of smoke on the flight deck, pilot positions havesmoke hoods and /or goggles together with oxygen masks that do not mix the oxygen with cabinair. Smoke in the passenger cabin is most likely from a malfunction in the galley, or frompassengers illegally smoking in the toilet compartments.In the event of smoke in the passenger compartment requiring the use of the drop-out oxygenmasks, passengers are reluctant to cover their mouths. The cabin crew must be forceful inensuring compliance with the Commander's instructions to don the oxygen masks. Necessarydrills and training are in the Operations Manual.

SMOKE IN THE CARGO COMPARTMENTOn the flight deck or in the passenger compartment, smoke is immediately obvious and the drillscan be actioned. Usually unmanned, any smoke present in the cargo compartment may escapeattention until warning devices indicate increased temperature due to the fire. To overcome this,linked smoke detectors (similar to domestic smoke detector) are in cargo compartments andcrewmembers must visit the compartment (if possible) at regular intervals.

OPERACIJE U HITNIM SLUČAJEVIMA UNLAWFUL INTERFERENCE Any aircraft that is subject to unlawful interference shall endeavour to:

Notify the appropriate ATS unit of this factInform the ATS of any significant circumstancesNotify any deviation from the current flight plan necessitated by the above

This is to ensure that the ATS unit gives priority to the aircraft and minimises any risk of conflictwith other aircraft. The following procedures are intended as guidance for use by aircraft whenunlawful interference occurs and the aircraft is unable to notify an ATS unit of this fact.

PROCEDURES IF THE AIRCRAFT IS UNABLE TO NOTIFY AN ATS UNITUnless considerations on-board dictate otherwise, the Commander should attempt to continueflying on the assigned track and at the assigned cruising level until notifying an ATS, or, theaircraft is within radar coverage.Where the aircraft must depart from its assigned track or level without making radio contact withATS, the Commander should, whenever possible:1. Attempt to broadcast warnings on the VHF emergency frequency and any other appropriate frequencies, unless circumstances dictate otherwise2. Use other equipment such as on-board transponders, data links, etc. (conditions permitting)3. Proceed in accordance with the applicable special procedures for in-flightcontingencies, where such procedures are established and promulgated4. If there is no applicable regional procedure, proceed at a level which differs from the cruising levels normally used for IFR flight:300 m (1 000 ft) if above FL290, or150 m (900 ft) if BELLOW FL290.

OPERACIJE U HITNIM SLUČAJEVIMA PRESSURISATION FAILUREFailure of the pressurisation system of an aeroplane is potentially life threatening. At altitudesabove that at which the partial pressure of oxygen is no longer sufficient for normal respiration,exposure to ambient pressure causes hypoxia (lack of oxygen) leading to reduced brainfunctioning and failure of vital life systems in the body. Death results in a relatively short time.Unfortunately, the body is not very efficient at recognising the onset of hypoxia because the majoreffect is drowsiness and a gradual drifi to unconsciousness. For this reason, aircrafi havepressurisation failure warning systems to alert the crew when the required cabin pressure cannotbe maintained. If any failure of the pressurisation system occurs above a level where the outsideatmosphere can not support life, commence a descent to such a level immediately. Inform ATC ofthe descent (the RTF call preceded by MAYDAY x 3) and the pilot should broadcast level passinginformation and advise when stabilised at the lower level.

Failure of the pressurisation system can be caused by a general failure of the conditioningsystem, ruptures in the pressure hull of a size such that the system cannot cope with the rate ofloss of cabin air, total power failure (all engines out) or mishandling of the system by the crew.The classification of failures is by the rate of decompression of the cabin air: slow, rapid, orexplosive. Slow decompression occurs over a period of time because the system is trying toreplace the lost air and only losing the battle slowly. A failed door seal, stuck pressure dischargevalve, or an open window are likely causes. As the cabin altitude slowly climbs above 10 000 R(700 mb), a warning horn sounds and the drop out system operates after a delay atapproximately 14 000 ft. It is possible that physiological changes were noticed prior to this,especially by trained personnel, particularly 'ears popping', the onset of tunnel vision, pain in bodycavities, and excessive venting of air from the body.

OPERACIJE U HITNIM SLUČAJEVIMA Windshear is a change in wind direction and/or speed in either a vertical or horizontal sense. A simple definition is given by the UK CAA in a still valid AIC. Definition: Variations in vector wind along the aircraff flight path of a pattern, intensity,and duration to displace an aircraff abruptly from its intended path requiring substantialcontrol action.

LOW ALTITUDE WINDSHEARLow altitude windshear affects the take-off and landing and can be split into 3 motions:Vertical windshear: The change of a horizontal wind vector with height.Horizontal windshear: The change of a horizontal wind vector with horizontaldistance.Updraught/downdraught: Changes in the vertical component of wind with horizontaldistance. A windshear encounter can affect large aircraff suddenly by displacing them beyond the pilot's powers of recovery.

METEOROLOGICAL FEATURESSevere windshear is associated with cumulonimbus or towering cumulus clouds.However, windshear can also be experienced in association with other features such as the passage of a front, a marked temperature inversion, a low-level wind maximum, or a turbulent boundary layer. Topography or buildings can make the situation worse when there is a strong wind.

OPERACIJE U HITNIM SLUČAJEVIMA THE EFFECTS OF WINDSHEAR ON AN AIRCRAFT IN FLIGHTIn windshear the magnitude of the change of wind vector and the rate at which it happensdetermine the severity. An aeroplane at 1000 ft agl may have a headwind component of 40 ktwith a surface headwind component of only of 20 kt on the runway. The 20 kt difference mayreduce evenly and the effect is negligible, or if the speed differential still exists at 300 ft thechange through further descent is marked. Windshear implies a narrow borderline and the 20 ktof wind speed may well be lost over small vertical distance.

As shown in the diagram, the loss of airspeed when passing through the shear line is sudden.I The inertia of the aircraft keeps it at its original ground speed of 100 kt and power is needed toaccelerate the aircraft back to its original air speed. This takes time and there is sinking, as lift islost. The headwind was kind of energy and when it dropped 20 kt, an equivalent amount ofenergy loss occurred.

OPERACIJE U HITNIM SLUČAJEVIMA The opposite effect happens when taking off. Assume a climb with a 10 kt headwind, whichchanges to a 30 kt headwind. The target climb speed is 120 kt. The effect of a sudden transitionto a 20 kt increase of headwind increases the IAS by the same amount until the momentum of theground speed is lost. The aircraft climbs more rapidly with the added lift.

OPERACIJE U HITNIM SLUČAJEVIMA TECHNIQUES TO COUNTER THE EFFECTS OF WINDSHEAR

There is no international agreement for grading windshear. Always plan for the worst casescenario. If the forecast calls for thunderstorms at the planned destination, then expect windshear and give consideration to the following. lncrease the airspeed on the approach. Rule of thumbguidance include adding half the headwind component of the reported surface wind to VAT. or, half the mean wind speed plus half the gust factor, in each case up to a maximum of 20 kt.Where a sudden increase in airspeed occurs, the normal reaction to the rise above the glidepath is to reduce power to regain the glidepath. The pilot must be alert to the need to increase power in good time to avoid dropping below the glidepath. In the later stages of an approach windshear can be much more hazardous. A drop in the wind speed might bring about a very sudden drop in airspeed with an increase in the rate of descent. A rapid and positive increase in power isneeded.

Vital actions to counter loss of airspeed caused by windshear near the ground:

lncrease power to full go-aroundRaise the nose to check descent (to stick shaker operation)Co-ordinate power and pitchBe prepared to carry out a missed approach rather than risk landing from adestabilised approach

OPERACIJE U HITNIM SLUČAJEVIMA WAKE TURBULENCE SPAGING MINIMA - DISPLACED LANDING THRESHOLD Use a spachg of two minutes between medium or light aircrafl following a heavy aircraft, and light aircraft following a medium aircrafl when operating on a runway with a displaced threshold when:

A departing medium or light aircraft follows heavy aircraft or a departing lightaircraft followsa medium aircraftAn arrving medium at light aircraft follow a heavy aircraft departure, or an arriving llght aircraft follows a departing medium aircraftExpecting the projected flight paths to cross

WAKE TURBULENCE SPACING MINIMA - OPPOSITE DIRECTION

A Spacing of two minutes between a midium or light aircraft and a heavy aircraft, and between a medium aircraft and a light aircraft whenever the heavier aircraft is making a low or mised approach and the lighter aircrafl is:

Taking-off on the same runway in the opposite directionLanding on the same runway in the opposite directionLanding on a parallel opposite direction runway separated by less than 760 m

WAKE TURBULENCE SPACING MINIMA - CROSSING AND PARALLEL RUNWAYSWhen parallel runways separated by less than 760 m are in use, consider these runways assingle runways.

WAKE TURBULENCE SPACING MINIMA - INTERMEDIATE APPROACHOn intermediate approach, apply a minimum wake turbulence spacing of 5 nm between a heavyand a medium or light aircraft following or crossing behind.

OPERACIJE U HITNIM SLUČAJEVIMA BlRD HAZARD REDUCTIONAssess the bird strike hazard on, or near, an aerodrome, through the establishment of a national procedure for recording and reporting bird strikes to aircraft, and the collection of information from aircraft operations personnel on the presence of birds on or around the aerodrome. Report all bird strikes.

On aerodromes, the use of the following deters birds congregating in large flocks:Long grassBird scaring techniques such as: Pyrotechnics (most effective) Bird distress qalls

Rubbish tips or other equivalent waste areas attract birds. A bird generally reacts to the proximity of an aircraft within 3 seconds.

BIRD HAZARDS AND STRIKESWhen a potential bird hazard is observed, the Commander immediately informs the local ATSU.Where a bird strike occurs then a written bird strike report is submitted to the authority after landing, if the aircraft sustains significant damage. If the Commander is unable to do this, then the operator must submit the report.

OPERACIJE U HITNIM SLUČAJEVIMA IBISICAO established a system to collect and disseminate information concerning bird strikes, known as IBIS (ICAO Bird Strike Information System). Other sources of information include pilot reports, NOTAMS, ground radar detections, and aerodromes VCR observations. Where specific aerodromes are on migratory routes, local information may be broadcast on ATlS or a BIRDTAM may be promulgated.

OPERACIJE U HITNIM SLUČAJEVIMA EMERGENCY AND PRECAUTIONARY LANDINGS

In extreme circumstances, it may become inevitable that further flight is neither desirable norpracticable, forcing the Commander to make a decision to land as soon as possible. Theprocedures for diversion to an alternate aerodrome have been covered in detail, but a situationcould force the aeroplane to land on unprepared land or the surface of the sea. In either event,the procedures in the Operations Manual guide the actions of the pilots and crew. One point thatcannot be over-emphasised is that a decision to make such a landing must occur whilst the pilots are still able to control the aeroplane.

DITCHING

Ditching is the process of landing an aeroplane on the surface of the sea. During the designphase of the aeroplane construction, tests on computer and scale models occur in water tanks todetermine the ditching characteristics of the aeroplane. The effects are included in the aircraffmanual and pilots must be well briefed regarding the methods of ditching the aircraff during thetype rating course.Statistically, 88% of ditchings result in few if any, injuries to crew and passengers. Unfortunately,a much smaller percentage survives the ensuing 'survival' phase, with many deaths caused bydrowning after a successful ditching. Surviving the 'survival' phase is all about the speed ofrescue. This depends upon the accuracy and extent of the information conveyed to the ATCauthority by the crew during the run-up to the ditching.

OPERACIJE U HITNIM SLUČAJEVIMA PROCEDURE

Ditching is a controlled operation, with the aeroplane landing deliberately and smoothly (or assmoothly as possible) on to the surface of the sea, not dropped onto the surface during a stall. Itis recommended to land the aircraff across the swell (using a crosswind landing technique). If the wind speed is more than 35/40 kt, wave height may well exceed 10 ft making it more prudent to land into the wind in this case. A significant speed reduction and a definite nose up pitching happens, which can cause high-G rotations leading to possible structural damage and injuries.

To minimise the risk of injury, everybody on board should be securely strapped into their seatsand those without shoulder restraint harnesses should adopt a position with the head as farforward (ideally between the knees) and the hands clasped tightly behind the neck holding thehead forward. Life jackets should be donned before adopting the position. Cabin crew shouldensure that all loose articles are stowed and the seats are correctly positioned before securingthemselves.After rapidly coming to rest, providing there is no catastrophic fuselage damage, the aeroplanewill float for a considerable time allowing an orderly evacuation via the over-wing exits into the life rafts or dinghies. These should have been released from the in-wing stowages, but are stilltethered to the aeroplane.

OPERACIJE U HITNIM SLUČAJEVIMA PRECAUTIONARY LANDING

If the command decision is to divert to an enroute alternate, make a MAYDAY or PAN PAN call to ATC. The Rules of the Atr section of the Air Law notes, and the IFR and VFR Communicationsnotes cover the procedures for emergency communications. The ATC authority will activate thealerting service and the regional RCC will be informed of the emergency. SAR assets are alsoalerted. Preparations on the ground occur at the diversion aerodrome nominated to receive theaeroplane. Because the diversion is unplanned, ATC makes every effort to route other traffic outof the way of the aircraft in emergency, but compliance with ATC instructions regarding routing,heights, and speeds must occur (without exacerbating the emergency situation).

The possibility that the situation could deteriorate rapidly, requiring a forced landing or ditchingwith little extra warning, is foremost in the minds of ATC personnel. Measures such as scrambling long-range SAR aircraft and helicopters may appear some what 'over the top' at the time but such preparatory action may be crucial to saving lives later.

Within the restrictions of the situations, a normal, controlled landing should be made as well ascan be achieved. Once on the ground, the Commander must make a decision whether or not tomove the aircraft off the landing runway or bring the aircraft to a stop and immediately evacuatethe passengers and crew. This will depend very much on the nature and severity of theemergency situation. In any situation involving fire, all personnel must leave the aeroplane asquickly as possible. The fire rescue crew will attempt to control the fire until all personnel areevacuated.

OPERACIJE U HITNIM SLUČAJEVIMA PASSENGER BRIEFING

In an emergency situation, fear becomes the main enemy. Even the most seasoned traveller andthe most experienced crewmember experience at least apprehension in an emergency. Theinexperienced may tend to panic, and the cabin crew should attempt to impose strict discipline to Iovercome irrational behaviour, not only with regard to the passengers, but toward themselves aswell.

The most valuable weapon the crew has available is to keep the passengers informed of exactlywhat is happening. This, together with skill and calmness, provides the passengers theimpression that the situation is totally under control, even if this is not exactly the case. Attentionto detail (stowing small loose items, removing rubbish, and assisting in donning life jackets, etc.)reassures the passengers.

The flight crew should attempt to provide a virtual running commentary over the PA system. Thisfurther reassures and occupies the minds of the passengers. When the aeroplane is committed toa course of action: crash landing, ditching, or precautionary landing, a comprehensive brief to thecabin crew and passengers must happen. This must include a strong statement as to the Iauthority of the cabin crew and an order from the Commander for the passengers to do asinstructed.

Cabin crew should re-brief the emergency procedures covered during the pre-takeoff stage.

OPERACIJE U HITNIM SLUČAJEVIMA EVACUATION

Once the aeroplane has come to a stop after the landing, rapid evacuation is essential topreserve life. Fire is always a risk and the aim must be to get everybody as far away from the Iaeroplane as possible, During the briefing, the location of exits and the route to the exits should Ii be reiterated. Cabin crews will have trained in the procedures for evacuation, including strict discipline and firmcontrol, and the correct use of all the equipment provided to assist the evacuation. The Operatoris responsible for regular training sessions, and the drills to follow should be included in theOperations manual.

OPERACIJE U HITNIM SLUČAJEVIMA TCAS ALERTS AND WARNINGS

In the event that a Traffic Advisory (TA) is issued, commencement of a visual search for the threat aircraff should occur and preparation made to respond to a Resolution Advisory (RA), if one should follow. In the event that an RA is issued, initiate the required manoeuvre immediately.Note that manoeuvres should never be made in a direction opposite to those required by the RA, and that RAs should be disregarded only after positively identifying the potentially conflicting traffic and it becomes evident that no deviation from the current flight path is needed. Report all RAs to ATC verbally, as soon as practicable; and in writing, to the Controlling Authority, affer landing.

The pilot must react within 5 secondsA vertical speed of +/-1,500 fpm (acceleration = 0.25 g) is generally required, but may vary according to the eventPilots shall never manoeuvre in the opposite sense to the TCAS RA (RAs are coordinated with other suitably equipped aircraft)The pilot must inform ATC as soon as possible The "Clear of Conflict" message is issued when the aircraft diverge horizontallyThe pilot must then resume the ATC clearance