INSTRUMENT

LANDING

SYSTEM (ILS)Amidee bin Azizan

Present to

MR. Muzaffar MustaphaAir Traffic Controller of KLIA Department of Civil Aviation

Malaysia

SECTION 1

Outlines of ILS• Introduction to ILS• What is ILS?• The Uses of ILS• ILS Components• How Localizer Works• How Glide Path Works• ILS Categories• Marker Beacons

What Is ILS?

• ILS is stand for Instrument Landing System.• It has been existence for over 60 years.• But today, it is still the most accurate approach and landing

aid that is used by the airliners.• Why need ILS?

History of ILS

The first scheduled passenger airliner to land using ILS was in 1938.

The Uses of ILS• To guide the pilot during the approach and landing.• It is very helpful when visibility is limited and the

pilot cannot see the airport and runway.• To provide an aircraft with a precision final

approach.• To help the aircraft to a runway touchdown point.• To provide an aircraft guidance to the runway both

in the horizontal and vertical planes.• To increase safety and situational awareness.

Flight Profile

Poor Visibility Landings• Scheduled service would be impossible without a

way to land in poor weather.

Poor Visibility Landings

Runway Approach

10

Non-Instrument Runway (NI)

Non-Precision Runway (NP)

Precision Runway (P)

Threshold

Touchdown zone

Aiming point

Types of Runway Approach1.Non-Instrument Runway (NI)

• A runway intended for the operation of aircraft using visual approach procedure

2. Instrument Runway• A runway intended for the operation of aircraft using instrument

approach proceduresa) Non-Precision Runway (NP)

• An instrument runway served by visual aids and a non-visual aid providing at least lateral guidance adequate for a straight-in approach

b) Precision Runway (P) • Allow operations with a decision height and visibility

corresponding to Category 1, or II, or III

ILS category Height above touch down (HAT)/decision height (DH)

Runway visual range

CAT I HAT not less than 200 feet Not less than 1800 feet

CAT II HAT not less than 100 feet Not less than 1200 feet

CAT III A No decision height Not less than 700 feet

CAT III B No decision height Not less than 150 feet

CAT III C No decision height No RVR minimum

CAT 1• The visibility of the runway is at the minimum 1800 feet

(548,64 M)• The plane has to be equipped apart from the devices for flying

in IFR (Instrument Flight Rules) conditions also with the ILS system and a marker beacon receiver.

CAT 2• The visibility of the runway is at the minimum 1200 feet

(365,76 M)• The plane has to be equipped with a radio altimeter or an

inner marker receiver, an autopilot link, a raindrops remover and also a system for the automatic draught control of the engine can be required. The crew consists of two pilots.

CAT 3 -A• A minimal decision height lower than 100 feet (30,48 M)• The visibility of the runway is at the minimum 700 feet (213,36

M)• The aircraft has to be equipped with an autopilot with a

passive malfunction monitor or a HUD (Head-up di)

CAT 3-B• A minimal decision height lower than 50 feet (15,24 M)• The visibility of the runway is at the minimum 150 feet (45,72

M)• A device for alteration of a rolling speed to travel speed.

CAT 3-C• Zero visibility• A precision instrument approach and landing with no decision

height and no runway visual range limitations. A Category III C system is capable of using an aircraft's autopilot to land the aircraft and can also provide guidance along the runway surface.

Precision Runway (P) Categories• Runway Threshold: Beginning of runway for landing.

• Touchdown zone: The first point for the aircraft shoul touch the runway during landing.

• Aiming point: serves as a visual aiming point for a landing aircraft.

ILS Components• ILS consists of Ground Installations and Airborne

Equipments• There are 3 equipments for Ground Installations, which are:

1. Ground Localizer (LLZ) Antenna – To provide horizontal navigation2. Ground Glide path (GP) Antenna – To provide vertical navigation3. Marker Beacons – To enable the pilot cross check the aircraft’s

height.

• There are 2 equipments for Airborne Equipments, which are: 1. LLZ and GP antennas located on the aircraft nose.2. ILS indicator inside the cockpit

ILS Components

Ground Localizer Antenna

Ground Glide Path Antenna

ILS Indicator inside the cockpit

ILS Indicator

LocalizerDeviation from runway centre

line

GlidepathDeviation from optimal glide

path

Signal Integrity Flag

Indicates if instrument is

unreliable

“Dots”Each “dot” on the

instrument represents 2° of

deviation

How ILS works?• Ground localizer antenna transmit VHF signal in

direction opposite of runway to horizontally guide aircraft to the runway centre line.• Ground Glide Path antenna transmit UHF signal in

vertical direction to vertically guide aircraft to the touchdown point.• Localizer and Glide Path antenna located at

aircraft nose receives both signals and sends it to ILS indicator in the cockpit.

Cont.

• These signals activate the vertical and horizontal needles inside the ILS indicator to tell the pilot either go left/right or go up/down. • By keeping both needles centered, the

pilot can guide his aircraft down to end of landing runway aligned with the runway center line and aiming the touch down.

ILS Components

24

Localizer: horizontal guidanceGlide Path:

vertical guidance

Marker Beacons: the height aircraft

Question Banks• What is Localizer and how does it works?• What is Glide Slope and how does it works?• An Airport with an ILS is often rated as Cat 1 or Cat II or Cat III.

Explain the definition of these.• Explain Outer Marker, Middle Marker and Inner Marker of ILS

system.

Localizer• Localizer is the horizontal antenna array located at the

opposite end of the runway.• Localizer operates in VHF band between 108 to 111.975 MHz

How Localizer Works• Localizer transmit two signals which overlap at the

centre. • The left side has a 90 Hz modulation and the right has a

150 Hz modulation.• The overlap area provides the on-track signal.• For example, if an aircraft approaching the runway

centre line from the right, it will receive more of the 150 Hz modulation than 90Hz modulation. • Difference in Depth of Modulation will energizes the

vertical needle of ILS indicator. • Thus, aircraft will be given the direction to GO LEFT.

How Localizer Works

Right

Left

Localizer

Needle indicates direction of runway.

Centered Needle = Correct Alignment

Glide Path Antenna Array• Glide Path is the vertical antenna located on one side of the runway

about 300 m to the end of runway.• Glide Path operates in UHF band between 329.15 and 335 MHz

How Glide Path Works

• Glide path produces two signals in the vertical plane.• The upper has a 90 Hz modulation and the bottom has a

150 Hz modulation.• For example, if an aircraft approaching the runway too

high, it will receive more of the 90 Hz modulation than 150Hz modulation. • Difference in Depth of Modulation will energizes the

horizontal needle of ILS indicator. • Thus, aircraft will be given the direction to GO DOWN.

How Glide Path Works

Glide Path

Needle indicates above/below glide

path.

Centered Needle = Correct Glide path

Marker Beacons• Marker beacons operating at a carrier frequency of 75 MHz

are provided. • When the transmission from a marker beacon is received it

activates an indicator on the pilot's instrument panel.• The correct height the aircraft should be at when the signal is

received in an aircraft.

Marker Beacons

Outer marker• The outer marker should be located about 7.2 km from the

threshold.• The modulation is repeated Morse-style dashes of a 400 Hz

tone. • The cockpit indicator is a blue lamp that flashes accordingly

with the received audio code. • The purpose of this beacon is to provide height, distance and

equipment functioning checks to aircraft on intermediate and final approach.

Marker Beacons

Middle marker• The middle marker should be located so as to indicate,

in low visibility conditions.• Ideally at a distance of 1050m from the threshold. • The cockpit indicator is an amber lamp that flashes in

accordingly with the received audio code.

Marker Beacons

Inner marker• The inner marker, shall be located so as to indicate in low

visibility conditions.• This is typically the position of an aircraft on the ILS as it

reaches Category II minima. • The cockpit indicator is a white lamp that flashes in

accordingly with the received audio code.

Advantages of ILS• The most accurate approach and landing aid that is used by

the airliners.

Disadvantages of ILS• Interference due to large reflecting objects, other vehicles or

moving objects.• This interference can reduce the strength of the directional

signals.

ILS Protected Area• ILS Critical Area- Aircraft and Vehicles are excluded during all

ILS operations.• ILS Sensitive Area

SECTION 2

Outlines of ATC• What is ATC?• How does the ATC function?• The problem with ATC• The solution

Air Traffic Controller

•

What is ATC system?• ATCS or ATC is a government run organization that is part of

FAA and DCA

• The ATC control all the air traffic on the Malaysia (DCA)

• Controller can gives the aircraft attitude, speed and direction at any time to the pilot

• The controller also gives directions and weather forecast to the pilot. If this command were to missed or interpreted differently , the result could be catastrophic.

How does ATC function• When the aircraft take-off, the departure control which is in the terminal

radar control facilities TRACON give the aircraft direction while the aircraft remain the TRACON airspace.

• It then switches over the middle zone, where the air route traffic control center ARTCC take over from the TRACON

• In the ARTCC zone two controllers monitor the aircraft, called the radio associate controllers

• The associate and radar controller work together in charge of their own zone. The radar controller controls all air to ground communication to maintain aircraft separation within the zone and coordinates activities with others sector and/or center

The Problem of ATC• The technology used with the

ATC is outdated*The radar that are used date back to WW2*The radio sets that are used date all the ways back to the 1960s

• There is an excessive amount of AT congestion

*Too many aircraft flying means that the airways are not safe, and airborne collisions are more likely to happen

• Weather*Thunderstorm cause major delays if not correctly redirected*poor Visibility

The Solution• First, replace all of the old

technology with the new technology

*GPS systems installed in planes and controlled*satellites used to give weather and create flight maps and routes

• Weather issues can be solved by implementing the technology of satellite

*Air routes can be changed via GPS if a storm is predicted

• Airways Congestion

*New technology can be implemented to solve this problem.

-Aircraft will get ’ turn by turn’ directions to get to destinations and to avoid other aircraft*Replace all the old jets, with newer, more fuel efficiency jets.

-newer jets can fly through the air at faster rates and do not struggle as much as older jets.

SECTION 3

Future Development

ILS VS MLS

What is MLS?

• MLS (Microwave Landing System) is an advanced precision approach and landing system.• MLS was developed to improve the uses of ILS system,

however only few Airports have MLS installations.• MLS operates in the Super High Frequency (SHF)

between 5.031 to 5.090GHz.

Advantages of MLS• MLS provide large coverage signals even in very poor

visibility.• As MLS signals have large coverage, this will increase

runway utilization.• MLS also has more channels which can avoid the signal

interferences.

MLS Coverage

MLS vs ILS• Aircraft flying into Heathrow Airport in fog or poor

visibility.• On a clear day, about 44 planes an hour land at

Heathrow. • However, if the visibility drops and aircraft have to use

the ILS system to land, only 24 aircraft could land per hour. • This is because the radio transmitter at the end of the

runway needs good line of sight to the approaching aircraft, but because it is at the far end of the runway, planes have to land and taxi clear before a full signal is restored.• However, MLS allows an extra six aircraft an hour to land,

meaning that while fog will still cause disruption, its effects will be less prominent.

MLS Ground Installations

An MLS azimuth (horizontal) guidance station

MLS Ground Installations

An MLS elevation (vertical) guidance station

ATC NEXT GEN 2018

NEXt Gen 2018

• A government run project to upgrade the technology of the ATC• Upgrades include a GPS

and satellite system in every airplane• Next Gen 2018 has two

major fundamental problems

• The project has no market-based infrastructure to support all the ATC receiving.

-Without this, the project would be just like expanding a toll-free highway. Sooner or later, the highway will be just as crowded as it was before.

• Next Gen 2018 also might have a problem implementing the right technology.

• The whole process of upgrading the ATC will happen again.

SECTION 4

ILS related to the ATC• ILS is the equipment that guide the pilot landing to the

touchdown point and also known as the ATC technology• This equipment is the helpful to the ATC because the ATC no

need to *Guide the pilot by their self.

• The ATC just control the aircraft at the TRACON area and guide to the marker beacon area for aircraft connecting by antenna to the ILS for make a landing.

• This equipment was supporting the ATC and it’s a useful to the aircraft and also the ATC got the benefit from that.

Resources• Lecture Note- Mr Muzaffar and Major Maya• Wikipedia website• FAA website• NASA website• DCA website• New Technology of ILS –PDF file

Conclusion• For airport all over the world, cost-efficiency, environmental

protection and passenger comfort are at the top of the agenda. However, due to the complexity of everyday airport operations and new aircraft fleet to achieving these goals is uncertainties and this is where equipment like ILS and ATC working principles/procedure helping to minimize error and problem although increasing efficiency in flight scheduling procedure , safety, time accuracy and airport profitability

Result: Improved overall situational awareness and flight operation quality

SPECIAL THANKS TO MALAYSIA AIRPORT HOLDINGS BERHADMr Muzaffar Mustaffa

Major MayaKPMC

Q&A