airport operations chapter_1 i

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Chapter IAirport Operations:

ObjectiveThe objective of this chapter to learn the airport, its evolution and various areas of theairport

What is an airport?

According to the International Civil Aviation Organization, an aerodrome is a defined areaon land or water (including buildings, installations, and equipment) that is intended to be

used either wholly or in part for the arrival, departure, and surface movement of aircraft.Aerodrome is now largely a technical term and is no longer in common use. More

usually the terms airport and airfield are employed, although there is some lack of precisionin their meanings.

Airport is used particularly to denote areas where air-transport passengers are carried,especially where movement occurs on a considerable scale and always where full-time

customs facilities are available.Airfield commonly refers to small aerodromes (often without paved runways) or

facilities for handling air-transport aircraft or their passengers and cargo.In addition, at large airports the term often designate the operational areas for aircraft,

including the runways, taxiways, aprons, and strips.

Evolution of airports

The requirements for aerodromes, or airports, have increased in complexityand scale since the earliest days of flying. Before World War II the landing and takeoff

distance of most passenger-transport aircraft was at most 650 yards (600 meters). Additionalclear areas were provided for blind landings or bad-weather runs but the total area involved

rarely exceeded 500 acres (200 hectares).

It was not until the general introduction of heavy monoplanes for transport,

such as the Douglas DC-3, during the late 1930s that extensive takeoff and landing distances

were needed. Even then, the prewar airfields at New York City (La Guardia), London(Croydon), Paris (Le Bourget), and Berlin (Tempelhof) were laid out on sites close to the city

centres. Because even transport aircraft of the period were relatively light, paved runwayswere a rarity. Croydon, Tempelhof, and Le Bourget, for example, all operated from grass

strips only. Early airports were also major centres of leisure activity, often attracting more

visitors than passengers.

In 1939 La Guardia Airport attracted almost a quarter-million visitors per

month, reaching a peak of 7,000 in one day, compared with a maximum daily throughput ofonly 3,000 passengers. In 1929 Berlin's airport reported 750,000 visitors and boasted a

restaurant that could seat 3,000 people on the roof of the passenger terminal.


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The status of prewar airports as major social centres was reflected in theirdesign, especially where the requirements of catering, observation decks, and parking were

paramount. Indeed, the requirements of aircraft and passengers were not at all dominant atearly airfields.

Much long-distance air transport was handled by the large seaplanes known asflying boats or clippers. These aircraft though slow and of limited range, offered a level ofcomfort that was necessary for long-distance travel. Air terminal facilities were necessarily

constructed close to large, open stretches of water. La Guardia Airport and Santos DumontAirport in Rio de Janeiro are examples of airports that still operate on sites originally chosen

for their ability to handle large seaplanes. The large facilities at Southampton Water in theUnited Kingdom have now disappeared, but the artificial lake at Linate Airport near Milan,

Italy, is still to be found close to the present administration facilities.

The vast majority of airfields throughout the world are still relatively simplefacilities. Even now, many have unpaved runways or at most lightly paved runways with tiny

terminal or administration buildings, a rudimentary control tower, and crude landing aids.Such facilities can deal only with light aircraft and a negligible flow of passengers or freight.

Heavy air traffic, on the other hand, is now almost entirely handled bysophisticated airport facilities that can accommodate the needs of crew, passengers, and

freight and the great range of aircraft types that have evolved to meet the needs of modern airtransport and general aviation.

Approximately 50 airports around the world now handle more than 10 million

passengers per year; half of these are in the United States. Six airports regularly move 30million passengers on a yearly basis -- Chicago's O'Hare International Airport alone handling

60 million. In order to meet the increasing demand for air travel, large transport aircraftpowered by multiple jet and turboprop engines have been built.

Such aircraft require extensive ground facilities, runways, taxiways, fire-

fighting and rescue services, passenger- and cargo-handling facilities, access to car parkingand public transport, lighting, navigational and approach aids, and various support facilities

such as catering, meteorology, and governmental inspection.

In order to be attractively convenient, the complex of activities and facilities

that make up a modern airport must be located sufficiently close to the main centres of worldpopulation. At the same time, they must be adequately distant, so that the environmental

problems associated with the noise of large aircraft and the activities of large numbers ofpassengers, workers, and visitors do not become intolerable to the cities that are served.

(Ref: 1994-1998 Encyclopedia Britannica)

Modern airports

The largest airports in the world employ more than 100,000 workers each. They are

immensely complex entities with regard to the physical facilities that they comprise, the


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organizations that are active within their boundaries, and the services that are provided inconjunction with their operation.

Physical facilities include runways, taxiways, aprons, and strips, which are used for the

landing and takeoff of aircraft, for the maneuvering and positioning of aircraft on the ground,

and for the parking of aircraft in order to load and discharge passengers and cargo. For thesafe landing and takeoff of aircraft, lighting and radio navigational aids are provided. Theseare supplemented by airfield markings, signs and signals, and air traffic control facilities.

Support facilities on the airside of the field include meteorology, fire and rescue, power andother utilities, aircraft maintenance, and airport maintenance. Landside facilities are the

passenger and cargo terminals and the access system, which includes parking, roads, publictransport facilities, and loading and unloading areas.

Many organizations are involved in the operation of a modern airport. Overall

management is usually in the control of an organization, authority, or company that holds alicense to operate the facility. This license is granted subject to a judgment by the national

civil aviation authorities that the managing body is fit and competent to run an airport withinnational and, if applicable, international laws governing safety and operations.

While overall responsibility for efficient, safe, and legal operation lies with the airportmanagement, many of the individual services at an airport are provided by other

organizations. Such organizations include airlines; air traffic control authorities; groundhandling companies; fixed-base operators; concessionaires; security organizations;

governmental agencies responsible for customs, immigration, health control, and police;support companies providing flight catering, fueling, aircraft engineering, and maintenance;

aero clubs; and flying schools. Since the early 1980s, when privatization began to sweepthrough civil aviation, terminal-operation companies have also become more frequent, such

as those that own terminals in Birmingham, Eng.; Brussels; and Toronto.

AIRSIDE


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Airport services related to the aircraft are frequently referred to as airside. Many of theseservices are concentrated on the apron, or ramp, which is that part of the operational surface

adjacent to the terminals where aircraft are maneuvered or parked. They include the apronhandling of aircraft, airside passenger transfer to the aircraft, the handling of baggage and

cargo, aircraft fueling, catering and cabin cleaning, engine starting, deicing, ground power

and air-conditioning, and minor maintenance engineering. Other airside services are runwayinspection, lighting and navigational aids, fire fighting and rescue, airside maintenance, andair traffic control. Among the landside services are those related to ground passenger

handling; these include check-in, security, customs and immigration, baggage delivery,information, catering, cleaning and maintenance, shops and concessionary facilities,

automobile rental, ground transportation, porters, special help for the elderly andhandicapped, automobile parking, and public transportation (including taxis). In addition,

because airports employ such a large number of workers, extensive provision must be madefor their daily requirements.

The process of selection and construction of a New Airport

SITE SELECTION

Aeronautical and environmental factors.

Selecting a site for a new airport, or evaluating how well an existing site can be

expanded to provide a new major airport, is a complex process. A balance must be achievedbetween aeronautical and air-transport requirements and the impact of the airport on its

environment.

From an aeronautical viewpoint, the basic requirement of an airport is that it have a

relatively flat area of land sufficiently large to accommodate the runways and other facilities

and that this area be in a locality free from such obstructions to air navigation as mountainsand tall buildings.

From the viewpoint of air-transport needs, airport sites must be sufficiently close topopulation centres that they are considered reasonably accessible to their users.

Environmental considerations, on the other hand, dictate that the site should be farenough away from urban centres that noise and other deleterious effects on the population

should be kept to acceptable levels. Furthermore, the airport should not destroy areasof natural beauty or other significance. These two sets of requirements, the aeronautical and

the environmental, almost inevitably clash, the conflict becoming more severe as the scale ofthe envisaged airport increases.

The most modest airport facility--with a single runway, an apron, and a building thatserves simultaneously as terminal, administration area, and control tower--can comfortably

be built on a site as small as 75 acres, since it requires only a flat, well-drained area sufficientto accommodate a short runway and its surrounding safety strip.

Larger and more modern airport facilities, on the other hand, require multiple runways

of extended length, extensive terminal apron areas, and large expanses of land devoted to


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parking and landside access roads. For such an airport, a minimum area of 3,000 acres islikely to be required. Several major airports--such as Dallas-Fort Worth International Airport

in Texas, King Abdul Aziz International Airport near Jeddah, Saudi Arabia, and Charles deGaulle Airport near Paris--are built on sites well in excess of this figure.

The selection process.The site-selection process for large airports can take many months; in some notable

cases it has extended over many years. The procedure is complicated by the number of

factors that must be taken into account.First, the operational capability of the site is assessed, particularly with respect to

weather conditions such as wind, snow, ice, fog, and low visibility and also with respect toobstructions to air navigation around the airport, particularly on the approach and takeoff

paths.The location of the facility in relation to air-traffic-controlled airspace is also

operationally important. In addition, there must be an evaluation of the capacity of theavailable land to accommodate the expected configuration of runways and other facilities.

Flat or very gently undulating land is necessary, because runways must be constructedaccording to restrictions on maximum allowable slopes--which, in turn, are governed by

aircraft performance on landing and takeoff.

Ground access to the airport is also considered. An evaluation is made of the distance

from population centres, the regional highway infrastructure, public transport facilities

(including railways), and the availability of land for parking.

Development costs are also estimated, taking into account the nature of the terrain, soil

and rock conditions, drainage requirements, and local land values.

The environmental consequences of an airport development rank very high in any site-selection procedure. The impact of aircraft noise on the neighboring population is often the

most significant environmental factor, but in many countries account must also be taken ofthe impact on the flora and fauna of the area, pollution through chemical runoff into local

groundwater, the presence of endangered species or significant cultural sites, and evenundesirable changes in land use. Many governments now require that environmental analyses

of airport development projects include evaluations of population relocation, changes inemployment patterns, and distortion of existing regional land use and transportation

planning.

(ref: Encyclopedias Britannica)

PASSENGER TERMINAL LAYOUT AND DESIGN

Passenger requirements.

As passengers throughout at airports increases, the passenger terminal becomes a moreimportant element of the airport, attaining a dominant status in the largest facilities. The

passenger terminal may amount to less than 10 percent of the total investment in a smallairport, but at large airports terminals often account for more than 70 percent of


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infrastructural investment. The design that is ultimately adopted depends principally on thepassenger volumes to be served and the type of passenger involved.

Passengers are frequently classified as business or leisure, scheduled or charter,

originating or destined, and transfer or transit. Business travelers tend to pay significantly

higher fares, and airlines usually wish to provide a high quality of service in order to attractsuch traffic. The passenger terminal at Heathrow Airport near London, for example, wasdesigned to a very high standard of space and decor to attract just this type of passenger.

Scheduled and charter passengers, meanwhile, tend to have very different needs in theterminal, especially at check-in and in the provision of ground transportation. Palma Airport,

on the Spanish island of Majorca, has a landside that is designed to accommodate largenumbers of charter tourists arriving and departing the airport by bus.

Some airports have a very high percentage of passengers who are either transiting the

airport (i.e., continuing on the same flight) or transferring to another flight. At HartsfieldAtlanta International Airport in Georgia and at Chicago's O'Hare International Airport, for

example, two-thirds of all passengers transfer to other flights and have no wish to visit thecities where the airports are sited. These passengers have special needs but usually only on

the airside of the terminal. There is no need to provide parking or ground transportation tothe city for such passengers; they will, however, need transit lounges and other areas such as

transit check-in desks.

Airports that receive a large number of transferring and transiting passengers are

referred to as hubbing airports. At a hub, aircraft arrive in waves, and passengers transferbetween aircraft during the periods when these waves are on the ground. By using a "hub-

and-spoke" network, airlines are able to increase the load factors on aircraft and to providemore frequent departures for passengers--at the cost, however, of inconvenient interchange at

the hub

PASSENGER TERMINAL.

The passenger building is obviously the main point of attention to the traveling public.

It is the design of the terminal building which more than often determines the airportmanagements efficiency and capability in the eyes of the public.

The passenger building is the major connection between airport access and the aircraft.

The purpose of the passenger building is to

1. Interface with the passenger mode of aircraft access2. Process departing and arriving passengers

3. Convey the passenger to and from the aircraft

These three components could be discussed as access interface, processing and flight

interface respectively


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What are the considerations which influence the design of the passenger terminal?

Airport Management and airlines agree that the most important person in the terminalbuilding is the passenger, whether in transit, departing or arriving..

Experience in the use of airport building has made certain overall requirements andplanning principles which should be considered These are:

1 Building should be functional, simple in design and structure, economical to main andcapable of expansion without major structural changes. It is better to build in progressive

stages to that all airport operations many continue to grow architectural design while thebuildings are in use. This is a very important consideration. It is well known tat in recent

years in the oil producing countries, terminal building have been built as architecturalmonuments at enormous cost. What is accepted, no doubt, is the needs to have outstanding

architectural design, which blends harmoniously both the natural/traditional architecturaldesign and contemporary architecture more suited to passenger services

2 There should be a clear cut functional separation between the airline and other concerned

operational facilities and those elements are directly related thereto. It is important tomaintain a functional separation between the two major types of facilities in an airport i.e.

those for aviation activities and those for non-aviation activities, and facilities for the generalpublic.

3 Public services/facilities should be closely related to the airport passenger handling area andshould be readily accessible to each of its parts

In large airports with decentralized terminals public services may also have to bedecentralized in order to;

y Reduce the average distance a passenger must walk to reach such services;

y Make more services available to passengers

y Reduce the time interval required to reach and use such services;

y The travel distance between ground transportation and aircraft should be kept at minimumdistance. The size of the ultimate development of the airport, particularly within the

administrative and terminal building area will determine whether the general plan is to becentralized or decentralized


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The components of the passenger-handling-together with the specific physical facilitiescorresponding to them may be seen in the figure 2.

Figure 2

The facilities that a passenger required are provision of sufficient space in the buildingfor restaurants, snack bars, shopping arcade, toilet, adequate space for expeditious facilitation

of arriving and departing by international flight through immigration and customs

PASSENGER TERMINAL CONCEPTS.


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What should be the concept of a passenger terminal? There has been a considerable

debate on it. Two concepts of terminal designs have been developed, namely centralized and.decentralized terminal. While deciding which of the concepts will suit a particular airport,

the economics and suitability of the terminal in terms of the total area, manpower utilization

and the convenience available to the passenger and airlines have to be examined

CENTRALIZED TERMINAL

In a centralized terminal concept, one single interface building, situated between

landside and airside serves all aircrafts respective of their size and number. All diversifiedfunctions of a terminal are controller in one area. Expansion of facilities necessitated with

the growth of traffic can be incorporated easily without duplicating them. The separateexpansion of apron and terminal areas is possible in this concept without much

inconvenienceThe centralized concept has a major drawback in its ever increasing walking distances

for the passengers between the aircraft and the terminal building. However this defect hasbeen overcome in a centralized type of terminal like Dulles International Airport,

Washington, which has no fingers or satellites, but only a terminal building and large remoteparking apron. Passengers are transported between the two point in special vehicle known as

mobile lounges. This type of terminal concept has been adopted in the new MontrealInternational Airport at Mirabelle, and the Jeddah Airport in Saudi Arabia.

DECENTRALISED TERMINAL

In a decentralized concept, the functional requirement of a fewer number of aircraft; say 4 to6, at a time are handled in one common facility. When the number of aircraft increases, a

series of modules are developed to meet the requirements. This development of modules,instead of one large single terminal is known as the decentralized concept.

The decentralized or modular concept permits better provision of passenger convenience. It

manages to keep walking distances short and size of the facilities to human scale. Howeverthe public conveniences in the decentralized concept require a certain degree of duplication

in staffing and inventory, I order to permit freedom to passengers to shop where and whenthe wish. The airport authorities in such cases have to take a policy decision on the extent to

which they desire to cater to public conveniences. This is an important factor of terminaldesigning that the airport terminal manager must decide

The development of finger type terminal and satellite terminal are variations of the

centralized and decentralized concepts. The most recent examples of decentralized terminalare at Dalas/Fortworth in Texas (USA). Charles de Gaulle in Paris(France) and the fabulous

Atlanta in USA. Built at a cost of US Dollar 500 million and built at located in an Area of3750 acres, the newly opened Atlanta Airport pushed the outer limits of technology and

ranks at the very top of the new generation airports.The design for the complex was refined for over more than a decade to fulfill two

basic requirementsto provide the most convenience and pleasant accommodation for itspassengers three quarters of whom change planes in Atlanta and to create the most efficient


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operating conditions for all the airlines. The four boarding concourses which are separatedby the main terminal concourses are connected by a superb, automatic rapid transit system

that takes passenger between the terminal and the farthest concourse in than five minutes.

CONCEPTS OF PASSENGERHANDLING

A clearer picture of the various concepts of the passenger handling will be availablefrom a perusal of the five concepts in Figure 3

a. Gate Arrival

b Pier Fingerc Pier satellite

d Remote Satellitee Mobile conveyance

Gate ArrivalThis is a decentralized passenger concept that is aimed at bringing the

vehicle close to the aircraft. The building is arranged in a one dimensional manner such thatcurb side facilities are close to the aircraft gate positions, thus reducing the walking distance

for the passengers.

Pier Finger-- This is a centralized processing concept. It is perhaps the most commonsystem to be found at airports at the present time.

The processing is done in a centralized building to which is attached a long corridor, called afinger that conveys passenger to an from parked aircraft outside

Pier SatelliteThis is a modification of the basic pier finger concept. Aircrafts are parked

around circular rotunda at the end rather than along the side of the finger. The advantage ofthis arrangement is that more space may become available to permit easy assembly of

passengers as well as ticketing activities at the aircraft gates

Remote SatelliteIn this system , aircraft are parked around units called satellites thatare separated from the main terminal building. Some processing activities e.g. ticketing,

passenger assembly, are performed at the main terminal building. This system allows partialdecentralization of the processing activities. It also permits a flexible aircraft circulation

pattern around the satellites. Conveyance of passengers between the main terminal buildingand the satellites occurs via corridors usually located below the apron level.

Mobile Conveyance.In thissystem, aircrafts are parked in groups remote from the

passenger terminal building. A mobile conveyance system, such as buses or mobile lounge isused to tae passengers to an from the aircraft. The main feature of this system is the

separation of aircraft and the passenger terminal building operations. These has theflexibility in adjusting to changes in aircraft characteristics such as size and maneuvering

requirements


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Figure 3


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AIRPORT UNITTERMINAL

It is worthwhile referring to a unique set up in the Kennedy Airport, New York and LosAngeles Airport. In Kennedy Airport, apart from terminal building, there are other terminals

operated by many airlines, including foreign carriers. These terminals known as unit

terminal have been designed and built by airlines themselves. The America national carrier,such as American Airlines, Pan Am , Trans World Airline, United, American and foreigncarrier British Airways have their own terminals. Each terminal has it distinctive

architectural feature

At Los Angles Airport, exit terminals are provided in a different way. The airportauthority has provided standard structuresland side buildings connected by tunnels to

satellite buildings on the air side. It rents them out to the airlines, exclusive of apron space.The airline may, subject to approval of the authority, install their own special facilities, such

as moving walk-ways in the tunnels of aerobridges on the satellites..

In Heathrow airport, London, BEA and BOAC(earlier name of British airways) desiredto construct their own terminal buildings, but the British Airport Authority , was not in favor

of the proposal because of the serious shortage of land in Heathrow airport

Terminal designs.

The various concepts by which airport passenger terminals can be designed are shown

in Figure 1.


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Figure 1

The oldest and simplest layout is the open apron design, in which aircraft park on the

apron immediately adjacent to the terminal and passengers walk across the apron to board theaircraft by mobile steps. Frequently, the aircraft maneuver in and out of the parking positions

under their own power. As airports grow, however, it is impossible to have large numbers ofpassengers walking across the apron. In this case, it is common to have terminals designed to


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the linear concept, with aircraft parked at gates immediately adjacent to the terminal itself.Usually, air bridges are employed for transferring passengers directly between the terminal

building and the aircraft. The limitation of the linear concept is usually the long buildingdimensions required; these can mean long walking distances for transferring passengers and

other complications related to building operation. In practice, building lengths tend to be

limited to approximately half a mile. Examples of the linear design occur at Kansas CityInternational Airport in Missouri, U.S., Munich Airport in Germany, and Charles de GaulleAirport near Paris.

Where one building must serve a larger number of aircraft gates, the pier concept, originally

developed in the 1950s, has been found very useful. Frankfurt International Airport inGermany and Schiphol Airport near Amsterdam still use such terminals. In the late 1970s,

pier designs at Chicagos OHare and Atlantas Hartsfield successfully handled in excess of45 million mainly domestic passengers per year. However, as the number of aircraft gates

grows, the distances that a passenger may have to travel within a pier-type terminal becomeexceedingly long, passenger circulation volumes become very large, and the terminal itself

can become uncomfortable and unattractive to use. In order to cut down walking distances,some terminals, beginning in the 1960s, were designed on the satellite concept. Frequently,

passengers are carried out to the satellites by some form of automated people mover orautomatic train. Some satellite designs were very successfulfor example, at Orlando and

Tampa in Florida, U.S.but to some degree the concept has fallen out of favor, having beenfound difficult to adapt to the changing size of aircraft and wasteful of apron space. Los

Angeles International Airport originally had all its aircraft served at satellite buildings, butduring the 1980s all satellites were converted to pier structures. (see also Index: Los Angeles

International Airport)

In the early 1960s the transporter concept originated as a method of reducing aircraftmaneuvering on the apron and of eliminating the need for passengers to climb up and down

stairways in order to enter or exit the aircraft. In a concept derived from much older designs(such as that at Linate in Milan, where ordinary apron buses are used), passengers are

brought directly to the aircraft by a specialized transporter vehicle. Mobile lounges used atDulles International Airport near Washington, D.C., at Jeddahs King Abdul Aziz

International Airport, and at Mirabel International Airport near Montreal have bodies that canbe raised and lowered to suit the exact height of the terminal floor and the aircraft sill.

However, passenger loading and unloading times are lengthened, causing turnaround delays,and aircraft are more likely to be damaged by the heavy lounges. For such reasons, this type

of design has not proved popular with either passengers or airlines.

The remote pier was introduced at Atlantas Hartsfield in the early 1980s. In this concept,

passengers are brought out to a remote pier by an automatic people mover and there embarkor disembark in the conventional manner. The system has proved very efficient for handling

transfer passengers, but the long distances involved in the terminal layout necessitate the useof a sophisticated people-mover system. The design of the terminal at Stansted, the third

London airport, incorporates this concept.


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The term unit terminal is used wherever an airport passenger terminal system comprises morethan one terminal. Unit terminals may be made up of a number of terminals of similar design

(e.g., Dallas-Fort Worth and Kansas City in the United States), terminals of different design(e.g., Londons Heathrow, Pearson International Airport near Toronto, John F. Kennedy

International Airport in New York City), terminals fulfilling different functions (e.g.,

Heathrow, Arlanda Airport near Stockholm, Barajas Airport near Madrid), or terminalsserving different airlines (e.g., Charles de Gaulle, John F. Kennedy, Dallas-Fort Worth). Thesuccessful operation of unit terminal airports has often required the design of rapid and

efficient automatic people movers such as those at Changi Airport in Singapore, at Dallas-Fort Worth, and at Houston Intercontinental Airport in Texas. (see also Index: Kansas City

International Airport, Heathrow Airport)

The apron area.

One of the important requirements in the design of a terminal complex is minimizing the

time needed to service an aircraft when it is transiting an airport. This is especially importantin the handling of short-haul aircraft, where unproductive ground time can consume an

unacceptably large percentage of flight time. The turnaround time for a large passengertransport between short-haul flights can be as little as 25 minutes. During this period, a large

number of service vehicles circulate on the apron. Therefore, an important aspect in theefficient operation of an airport facility is the marshaling of ground service vehicles and

aircraft in the terminal apron area. Such an operation can become extremely complex at someof the worlds busiest airports, where an aircraft enters or leaves the terminal apron

approximately every 20 seconds.

Immediately after World War II, new airports were designed with their terminals

entirely surrounded by runways, with access to the terminal areas provided by tunnels. Such

layouts include John F. Kennedy at New York and Londons Heathrow. Because many large

airports now discourage general aviation use by small aircraft, making crosswind runwaysunnecessary, the newest designs (including airports at Dallas-Fort Worth, Munich, andSingapore) have linear layouts of terminals set betweenparallel runways. Figure x shows

the linear development of Atlantas Hartsfield terminal within a complex of four parallelrunways. Such designs have been found to provide the most efficient relation between

terminal apron space and runways, minimizing marshaling problems and delays at the apronentrances.

THE DESIGN PROCESS.


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The design of airport passenger terminals is a complex procedure normally undertakenonly by experts in that area. Buildings are planned to accommodate comfortably the

passenger flows that are forecast to occur at some future date. In addition, it is anticipatedthat terminals will have to operate at levels slightly over capacity for short periods. The

measurements used are various, including such terms as standard busy rate and typical peak-

hour passenger flow, but by using these design procedures it is possible to plan a facility thatwill have insufficient capacity for no more than 30 operating hours per year. Under suchconditions, only about 5 percent of passengers would be subjected to inconveniences causedby lack of capacity

AIRPORT CAPACITY

The various facilities at an airport are designed to cope adequately with the anticipated flow

of passengers and cargo. The flow that any particular facility can accommodate withoutserious inconvenience to the users is considered to be its capacity. Limits on the traffic that

can reasonably be accommodated at an airport are reached in a number of ways. Theseinclude air traffic delays to landing and takeoff movements; congestion on runways,

taxiways, and aprons; crowding and delays in terminal buildings; or severe congestion insuch access facilities as parking areas, internal roads, and public transport.

At smaller one-runway airports, limits to capacity usually occur in the terminal areas,

since the operational capacity of a single runway with adequate taxiways is quite large. Whenpassenger volumes reach approximately 25 million per year, a single runway is no longer

adequate to handle the number of aircraft movements that take place during peak periods. Atthis point at least one additional runway, permitting simultaneous operation, is required.

Airports with two simultaneous runways should be able to handle approximately 55 to 65million passengers per year, and here, too, the main capacity problems are related to the

provision of adequate terminal space. Layouts with four parallel runways, as shown in Figure

30, are estimated to have operational capacities of well over one million aircraft movementsper year and annual passenger movements in excess of 100 million. The main capacityconstraints of such facilities are in the provision of sufficient airspace for controlled aircraft

movements and in the provision of adequate access facilities. It is likely that many of theworlds largest airports will face access problems before they reach the operational capacity

of their runways.

DRAINAGE

Large airports are actually urban complexes in which high-population activity centres are

closely associated with very extensive paved areas. Typically a large airport can, on a dailybasis, handle more than 100,000 passengers and support a working population of over 50,000employees. The sewage system of such an airport must cope with large daily flows of

sanitary sewage effluent and, in addition, must accommodate runoff from rain and snowaccumulating over several hundred acres of impervious pavement. The scale of the sewage

problem at many large airports is such that some facilities have their own sewage treatmentplants, especially for sanitary sewage. Because many airports are situated on low-lying


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ground, which is more likely to provide the flat land necessary for airstrips, the sewagesystem must often include extensive pumping facilities.

Growing concern about the environment and the increasing scale of activity at manyairports has meant that runoff water can no longer be drained directly into bodies of surface

water such as rivers and lakes. In particular, deicing chemicals used on aircraft and airfield

pavements and cleaning chemicals used in aircraft maintenance are serious contaminants ofgroundwater and surface water. Consequently, some airports are required to provide at leastprimary treatment of all runoff discharges, and there are legal restrictions on the nature of the

chemicals that can be used. In order to prevent groundwater pollution, the Munich Airportwas designed to accommodate existing flows of surface water across the entire site and was

also provided with extensive arrangements for the recycling of deicing chemicals.

NAVIGATIONAL AIDS, LIGHTING, AND MARKING

Only the simplest airfields are designed for operations conducted under visualmeteorological conditions (VMC). These facilities operate only in daylight, and the only

guidance they are required to offer is a painted runway centerline and large painted numbersindicating the magnetic bearing of the runway. Larger commercial airports, on the other

hand, must also operate in the hours of darkness and under instrument meteorologicalconditions (IMC), when horizontal visibility is 650 yards or less and the cloud base (or

decision height) is 65 yards or lower. In order to assist aircraft in approaches andtakeoffs and in maneuvering on the ground, such airports are equipped with sophisticated

radio navigational aids (navaids) and visual aids in the form of lighting and marking.

Navigationalaids.

The most common form ofnavaid used for the approach phase of aircraft descent is the

instrument landing system (ILS). This is a radio signal that is beamed along the centerline ofthe runway and at the correct angle of approach (usually 3 above the horizontal). The beamis intercepted by an approaching aircraft up to 15 miles from the threshold of the runway.

Information is given concerning position above and below the glide slope and deviation tothe right or left of centerline; consequently, the pilot is able to determine from cockpit

instruments a deviation of the aircraft from the proper approach.

Additional approach information is given visually to the pilot in the form of lighting

approach aids. Two systems of approach aids are in use: the visual approach slope indicator

system (VASIS) and the more modern precision approach path indicator (PAPI). Both workon the principle of guiding lights that show white when the pilot is above the proper glide

slope and red when below.

Airfield lighting.

Visual guidance to approaching aircraft is also provided by approach lighting systems,

a configuration of high-intensity white lights running along the centerline of the runway andextending up to 650 yards beyond the threshold. At airfields where aircraft operate in very

poor visibility, touchdown-zone lighting is provided over the first 1,000 yards from the


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runway threshold. These lights, set in patterns flush with the runway pavement, provideguidance up to the final moment of touchdown.

The runway itself is strongly delineated by a variety of guidance light systems. The threshold

is designated by a line of green lights, and the edges and centerline are delineated by white

lights that shine toward the maneuvering aircraft at regular intervals. The pilot is warned ofthe approaching runway end by a line of red lights at the end of the usable pavement.Taxiways are delineated by blue edge lights and by green centerline lights that also appear at

regular intervals.

Runway markings.

Considerable additional visual guidance is given to pilots by painted markings on the

runway. The form of marking indicates at a glance whether radio instrument guidance isavailable at any particular airfield. On precision instrument runways, the runway edges are

indicated by painted lines, and distances along the runway from the threshold are indicatedby pavement markings. In addition, touchdown-zone markings are painted on the pavement

immediately after the threshold, providing vital visual guidance during the momentsimmediately before touchdown when all lighting may be obscured by fog.

(Ref: Encyclopedia Britannica)

AIR TRAFFIC CONTROL

In the vicinity of airports--especially large airports, where in peak conditions as many

as three landing or takeoff operations may occur every minute--the control of aircraft in theair is a difficult but extremely important operation. Aircraft require very large amounts of

airspace, but at the same time the risk of collision must be set at very low, almost negligible,levels. Because aircraft are concentrated in the airspace around airports, acceptable levels of

collision risk can be achieved only by strict adherence to procedures that are set out andmonitored by air traffic control authorities.

An aircraft in flight follows en route air traffic control instructions as it flies through

successive flight information regions (FIRs). Upon approaching an airport at which a landingis to be made, the aircraft passes into the terminal control area (TCA). Within this area, there

may be a greatly increased density of air traffic, and this is closely monitored on radar byTCA controllers, who continually instruct pilots on how to navigate within the area. The

aircraft is then brought into the final approach pattern, at which point control passes to theapproach controller, who monitors the aircraft to the runway itself. Once on the runway, the

pilot is given instructions on ground maneuvers by the ground controller, whoseresponsibility is to avoid conflicting movements of aircraft in the operational area of the

airfield.

The ground controller gives the pilot instructions on reaching the apron stand position

via the appropriate turnoffs and taxiways. Final positioning may be the responsibility of anapron controller. Departing aircraft go through a reverse procedure, whereby control is


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passed from ground control to departure control to terminal control area and, finally, to enroute control.

CARGO FACILITIES

Less than 1 percent of all freight tonnage is carried by air. Nonetheless, this statisticsignificantly underestimates the importance of air freight because, in value of cargo moved,

air transport dominates all other modes. For example, although Heathrow Airport handlesless than three-quarters of a million tons of freight per year, in value of throughput it ranks as

Britain's premier port. By the early 1990s Tokyo's Narita Airport, New York's John F.Kennedy, and Frankfurt International Airport handled in excess of one million tons of cargo

per year.

As is the case with passenger facilities, freight terminals vary greatly in the volumes of

material handled. Consequently, the scale of the building facilities and the nature of the

handling methods also vary. Because only 10 percent of air cargo is carried loose or in bulk,all modern air-cargo facilities are designed to handle containers. In countries where labor is

cheap and where freight throughputs at the terminal are not high, freight-handling systemscan still be economically designed around the manhandling concept. This is not feasible in

developed countries, where labor costs are high. Even at facilities with small throughputs,freight is moved by mobile mechanical equipment such as stackers, tugs, and forklift trucks.

At high-volume facilities, a mixture of mobile equipment and complex fixed stacking andmovement systems must be used. The fixed systems, which require complex engineering

design and maintenance, are known as transfer vehicles (TVs) and elevating transfer vehicles(ETVs).

In the design of air-cargo facilities, special attention must be given to the handling ofvery heavy and oversized freight, perishables, urgent materials such as serums and human

donor organs, high-value goods such as diamonds and gold, hazardous goods, and livestock.

An area of very fast growth in the air-cargo business is specialized movement by integrated

carriers such as the U.S.-based Federal Express, which offer door-to-door delivery of small packagesat premium rates. In its early years, this type of freight grew by more than 17 percent per annum.Cargo terminals for the small-package business are designed and constructed separately from

conventional air-cargo terminals. They operate in a different manner, with all packages being cleared

on an overnight basis. RUNWAY PAVEMENTS

Until the introduction of heavy monoplane aircraft in the latter part of the 1930s, civil

air-transport aircraft were able to operate from grass runways with takeoff distances of lessthan 650 yards. The advent of heavy aircraft such as the DC-3 required the provision of

paved runways; at the same time, takeoff distances increased to more than 1,000 yards. Thelength requirements for runways continued to increase into the mid-1970s, when large


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civilian aircraft such as the Douglas DC-8 and some models of the Boeing 747 requiredalmost 4,000 yards of runway at sea level. (Even longer runways were necessary at higher

elevations or where high ambient air temperatures occurred during operations.) The trendtoward increasing runway lengths caused many problems at existing civilian airports, where

runways had to be extended in order to accommodate the new aircraft.

Ultimately, pressure by airport operators and the development of turbofan jet enginesarrested and finally reversed the trend. Since the 1970s, runway length requirements haveactually decreased, and the takeoff and climb performance of civilian aircraft has improved

substantially. This has brought a dual benefit in reducing the area of land required by anairport and also in reducing the area around the airport that is adversely affected by noise on

takeoff.

At all but the smallest airports, pavements are now provided for runways, taxiways,

aprons, and any other areas where aircraft are maneuvered. Pavements must be designed in

such a way that they can bear the loads imposed by aircraft without failure.

A pavement must be smooth and stable under conditions of loading during its expectedor economic life. It should be free from dust and other particles that could be blown up and

ingested into engines, and it must be capable of spreading and transmitting an aircraft'sweight to the existing subsoil (or sub grade) in a manner that precludes subsoil failure.

Another function of the pavement is to prevent weakening of the subsoil by moistureintrusion, especially from rainfall and frost.

Airfield pavements

Airfield pavements are of two types:

Rigid

Rigid pavements are constructed of Portland cement concrete slabs resting on aprepared sub base of granular material or directly on a granular sub grade. Load is

transmitted through the slabs to the underlying sub grade by flexure of the slabs.

Flexible

Flexible pavements are constructed of several thicknesses of asphalt or bituminousconcrete layers overlying a base of granular material on a prepared sub grade. They spread

the concentrated aircraft wheel loads throughout their depth until the load at the base of thepavement is less than the strength of the in situ soil.

At all depths the strength of the pavement should be at least equal to the loads placed

upon it by aircraft wheels. The choice of pavement type is often determined by economics. In


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some parts of the world, Portland cement concrete is cheaper than asphalt; in other parts, theconverse is true.

For certain parts of the airfield, however, asphaltic concrete is an unsuitable material

for pavement construction because of its vulnerability to damage by aviation fuel.

Therefore, even at airports where flexible airfield pavements are generally in use, it isusual for concrete pavements to be used where aircraft stand on the aprons and at runway

ends where fuel spillage is frequent.

Further Reading

y Airport Planning & Design by SK Khanna, MG Arora and SS Jain

y Strategic Airport Planning by Caves Robert E& Gosling Geoffrey. D

y Airport Engineering by Normal Ashford/Paul H Wright;

y Airport Management by Mr. S Ramanathan, Publisher SCOPE, New Delhi

airport operations chapter_1 i

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