Lecture notes in Airport Engineering

Tribhuvan University

Institute of Engineering Pulchowk Campus

Department of Civil Engineering

Introduction to Airport Engineering (M. Sc Transportation Engineering)

Prepared by:

Dr. Padma Bahadur Shahi March, 2011

Contents 1. 2. 3.

Airport Engineering ............................................................................................................................................ 3 Role of Air transportation: ................................................................................................................................... 3 Air Transport in Nepal ......................................................................................................................................... 3 3.1. Aviation Chronicles..................................................................................................................................... 3 4. Some organizations related to the civil aviation: .................................................................................................. 11 5. Classification of Airports:................................................................................................................................... 12 5.1. Based on take-off and landing ................................................................................................................... 12 5.2. Based on the Geometric design (ICAO)...................................................................................................... 12 5.3. Based on function: ................................................................................................................................... 13 5.4. Military aviation airports ............................................................................................................................ 13 6. Airlines frequency at different airports of Nepal: .................................................................................................. 14 7. Aircraft Component parts .................................................................................................................................. 14 8.1 Engine .................................................................................................................................................... 21 8.2 Fuselage: ................................................................................................................................................ 22 8.3 Wings: .................................................................................................................................................... 22 8.4 Three controls: ......................................................................................................................................... 22 8.5 Tricycle under-carriage: ............................................................................................................................ 23 9. Aircraft Characteristics: ..................................................................................................................................... 24 9.1 Size: ....................................................................................................................................................... 24 9.2 Make a figure of Minimum turning radius: ................................................................................................... 27 9.3 Minimum Circling Radius in Space: ............................................................................................................ 27 9.4 Capacity of aircraft: .................................................................................................................................. 27 9.5 Takeoff and landing distance: .................................................................................................................... 27 9.6 Speed of aircraft:...................................................................................................................................... 28 9.7 Weight of air craft and wheel configuration:................................................................................................. 28 9.8 Jet Blast: ................................................................................................................................................. 28 9.9 Fuel Spillage............................................................................................................................................ 28 9.10 Noise: ..................................................................................................................................................... 28 10. Aviation System Planning ................................................................................................................................. 28 10.1 Data base for airport system Planning: ....................................................................................................... 29 10.2 Comprehensive Airport system analysis ..................................................................................................... 31 10.3 Airport Master Plan................................................................................................................................... 32 10.4 Elements of Master Plan: .......................................................................................................................... 32 10.5 Steps of Master Plan ICAO: ...................................................................................................................... 33 11. Airport Site Selection ........................................................................................................................................ 33 12. Predicting air travel demand .............................................................................................................................. 33 12.1 Conventional methods of forecasting ......................................................................................................... 35 12.2 Analytical methods of air travel demand forecasting .................................................................................... 37 12.3 Air trip generation models ......................................................................................................................... 39 12.4 Air trip distribution models ......................................................................................................................... 39 12.5 Modal choice models ................................................................................................................................ 42 13. Airport Capacity ............................................................................................................................................... 43 13.1 Capacity, Demand and Delay ................................................................................................................ 43 13.2 Runway capacity ................................................................................................................................... 44 Airport Engineering/Dr. Padma Shahi

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13.3

Determination of runway capacities and delay .................................................................................... 45

1. Airport Engineering Airport engineers design and construct airports. Airport engineers must account for the impacts and demands of aircraft in their design of airport facilities. These engineers must use the analysis of predominant wind direction to determine runway orientation, determine the size of runway border and safety areas, different wing tip to wing tip clearances for all gates and must designate the clear zones in the entire port. Aviation is the design, development, production, operation, and use of aircraft. 2. Role of Air transportation: • Improves accessibility to otherwise inaccessible areas • Provides continuous connectivity over land and water (no change of equipment) • Saves productive time, spent on journey • Increase the demand of specialized technical skill workforce • Adds to the foreign reserve through tourism • Speed: Modern jet can travel at 1000 km/h • Promotion of trade and commerce • Military use • Relief and rescue operations • Aerial photography • Agricultural spraying • Safety: safe mode of transport. Disadvantages of air transport 1. Heavy funds are required, not only initially but also during operation 2. Operations are highly dependent up on weather conditions. 3. It needs highly sophisticated machinery: 4. Adds to the outward flow of foreign reserve 5. Noise pollution 6. Safety provisions are not adequate 7. Specific demarcation of flight paths and territories is essential. 8. High energy consumption 3. Air Transport in Nepal 3.1. Aviation Chronicles • • • • • • •

1949: The date heralded the formal beginning of aviation in Nepal with the landing of a 4 seater lone powered vintage Beach-craft Bonanza aircraft of Indian Ambassador Mr. Sarjit Singh Mahathia at Gauchar. 1950: The first charter flight By Himalayan Aviation Dakota from Gauchar to Kolkata. 1955: King Mahendra inaugurated Gauchar Airport and renamed it as Tribhuvan Airport. 1957: Grassy runway transformed into a concrete one. 1957: Department of Civil Aviation founded. 1958: Royal Nepal Airlines started scheduled services domestically and externally. 1959: RNAC fully owned by HMG/N as a public undertaking.

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• • • • • • • • • • • • • • • • • • • • •

1959: Civil Aviation Act 2015 BS. promulgated. 1960: Nepal attained ICAO membership. 1964: Tribhuvan Airport renamed as Tribhuvan International Airport. 1967: The 3750 feet long runway extended to 6600 feet. 1967: Landing of a German Airlines Lufthansa Boeing 707. 1968: Thai International starts its scheduled jet air services. 1972: Nepalese jet aircraft Boeing 727/100 makes a debut landing at TIA. ATC services taken over by Nepalese personnel from Indian technicians. 1975: TIA runway extended to 10000 feet from the previous 6600 feet. 1976: FIC (Flight Information Center) established. 1977: Nepal imprinted in the World Aeronautical Chart. 1989: Completion of International Terminal Building and first landing of Concorde. 1990: New International Terminal Building of TIA inaugurated by King Birendra. 1992: Adoption of Liberal Aviation Policy and emergence of private sector in domestic air transport. 1993: National Civil Aviation Policy promulgated. 1995: Domestic Terminal Building at TIA and Apron Expanded. 1998: CAAN established as an autonomous Authority. 2002: Expansion of the International Terminal Building at TIA and the construction of a new air cargo complex. 2003: Rara airport (Mugu), Kangeldanda airport (Solukhumbu) and Thamkharka airport (Khotang) brought in operation. 2004: Domestic operation by jet aircraft commenced. 2005: International flights by two private operators began. 2006: A new comprehensive Aviation Policy introduced. GMG Airlines of Bangladesh, Korean Air and Air Arabia started air service to Nepal.

Nepal has so far reached air service agreement and MoUs with more than 35 countries. Austria, Bahrain, Bangladesh, Bhutan, Brunei, China, Croatia, Egypt, France, Germany, Hong Kong, India, Israel, Italy, Japan, Jordan, Kuwait, Luxembourg, Macau, Malaysia, Maldives, Myanmar, Oman, Pakistan, Philippines, Qatar, Republic of Korea, Russian federation, Saudi Arabia, Singapore, Sri Lanka, Thailand, The Netherlands, United Arab Emirates, United Kingdom. In domestic service the airlines in the table are mainly functioning in different airports of Nepal. Civil Aviation Authority of Nepal has granted Air Operation Certificates more than thirty airline companies for scheduled/chartered operation, helicopter services and paragliding.

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4. Some organizations related to the civil aviation: • International Civil Aviation organization-ICAO o Established in 1944 as a result of Chicago convention Headquarter is in Montreal, Canada. o It is made up of an assembly, a council of limited membership with various subordinate bodies and a secretariat. o Assembly composed of representatives from all contracting states, is the sovereign body of ICAO o The council the governing body which is elected by the assembly for a three year term is composed of 36 states. o ICAO aims and objectives are to develop the principles and techniques of international air navigation and to foster the planning and development of international air transport so as to
Insure the safe and orderly growth of international civil aviation throughout the world. Airport Engineering/Dr. Padma Shahi

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Encourage the arts of aircraft design and operation for peaceful purposes Encourage the development of airways, airports, and air navigation facilities for international civil aviation
Meet the needs of the peoples of the world for safe, regular, efficient and economical air transport. o Strategic objectives for the period of 2005-2010:
Safety
Security
Environmental protection
Efficiency
Continuity
Rule of law • Federal Aviation Agency-FAA • Civil Aviation Authority of Nepal-CAAN • Airport Authority of India 5. Classification of Airports: There are different classifications by the related organizations such as ICAO, FAA etc. 5.1. Based on take-off and landing o Conventional take-off and landing airport (runway length > 1500 m. o Reduced take-off and landing airport (runway length 1000 to 1500m) o Short take-off and landing airport (runway length 500 to 1000m) o Vertical take-off and landing airport (operational area 25 to 50 sq. m.) 5.2. Based on the Geometric design (ICAO) o It employs aerodrome reference code, it consists of length of runway available
Classified using code number 1 through 4 o Aircraft wing span and outer main gear wheel span
Classified using letters A through E o ICAO classification based on wing span and outer main gear wheel span



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5.3. Based on function: • Civil aviation airports o Domestic airports o International airports o Combination of international and domestic 5.4. Military aviation airports

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6. Airlines frequency at different airports of Nepal:

7.

Aircraft Component parts 7.1. Engine 7.2. Propeller 7.3. Fuselage 7.4. Three control 7.5. Tricycle under carriage

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8.1 Engine Engine is required to provide the force for propelling the aircraft through the air. According to the method of propulsion aircraft engine can be classified as: 1. Piston engine: It is powered by gasoline fed reciprocating engine and is driven by propeller or airscrew. Engine rotates a shaft with a considerable amount of torque. Propeller is mounted on the shaft to absorb the torque. Rotating propeller attains its rated speed, huge masses of air is hurled rearwards thereby pulling the aircraft forward and creating lift on the wing. They are suitable to operate at low altitudes and moderate speed. They have cooling problem also. 2. Jet engine: advantages of jet engine a. they are free from vibration b. Simplicity of operation (no transmission or conversion mechanism is required) c. No radiators required d. No spark plugs are required e. No carburetors f.

Less consumption of lubricants

i)

Turbo Jet: to start the machine, the compressor is rotated with motor. As the compressor gains its rated speed, it sucks in air through the air intake and compresses it in the compression chamber. The air is ignited here by fuel. The expanding gasses pass through the fan like blades of turbine. The hot gasses escape through the tail pipe which becomes smaller in diameter and this hot gas having velocity, give a forward thrust to the engine.

ii)

Turbo Prop: It is similar to the turbo jet engine except that propeller is provided in it. Turbine extracts enough power to drive both the compressor and propeller.

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iii)

Ram Jet: It has no moving parts. It must be operated at high speed It requires the assistance of other types of power plant to reach the operating speed. The heated air expands and rushes out of the exhaust nozzle at high velocity creating jet thrust.

3. Rocket engine: It produces thrust in the same way as the ram jet engine except it does not depen upon the atmospheric oxygen. There is no limit on altitude.

An airplane can be single engine or multi engined. Single engine usually mounted at the nose of the fuselage. In two or four engined aircraft they usually housed in the leading edge of the aircraft. 8.2 Fuselage: It is main body of the aircraft and provides space for the power plant, fuel, cockpit, passenger, cargo etc. 8.3 Wings: Wings are required to support the machine in the air, when the engine has given forward speed.

PCosα

α PSinα

8.4 Three controls: There are three axes about which an aircraft in space may move to control these movements an aircraft is provided with three principal controls: Airport Engineering/Dr. Padma Shahi

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i)

Elevator: elevator consists of two flaps capable of moving up and down through an angle of 50-60 degree. They are hinged to a fixed horizontal surface at the extreme rear end of fuselage. It controls the pitch of the aircraft.

ii)

Rudder: It consists of a flap hinged to a vertical line provided at the tail end of fuselage. It is utilized for turning (or yawing) movement of the aircraft. It works just a boat is steered in water.

iii)

Aileron: it is hinged flap in the trailing edge of the wing. It is for rolling movement control.

X axis: rolling movement; Y axis: Pitching; Z axis: Yawing 8.5 Tricycle under-carriage: Tricycle undercarriage if for supporting the aircraft while it is in contact with the ground. Functions: •

To absorb landing shocks

•

To enable the aircraft to maneuver on the ground

Types: • • •

Single wheel assembly Dual wheel assembly Dual wheel assembly in Tandem

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9.

Aircraft Characteristics: 1. Engine type and propulsion 2. Size of aircraft 3. Minimum turning radius 4. Minimum circling radius 5. Speed of aircraft 6. Capacity of the aircraft 7. Aircraft weight & wheel configuration 8. Jet Blast 9. Fuel spillage 10. Noise

9.1 Size:

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Aircraft type

Wing span, m

Length, m

Maximum weight at take off, kg

Wheel track, m

Wheel base, m

Height, m

Cruising speed, km/ph

Boeing 747

59.6

70.5

351500

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25.6

19.3

940

Boeing 737

28.3

30.5

45600

5.3

11.4

11.3

850

Air bus 300

44.8

53.8

152000

9.6

18.6

16.6

900

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9.2 Make a figure of Minimum turning radius:

9.3 Minimum Circling Radius in Space: •

Small general aviation aircraft: 1.6 Km

•

Two piston aircraft: 3.2 km

•

Jet engine (IFR): 80 km 9.4 Capacity of aircraft: baggage, cargo, and fuel accommodated in the aircraft. 9.5 Takeoff and landing distance:

Factors affecting: gradient of runway, direction and intensity of wind, temperature, altitude, weight of aircraft etc. Airport Engineering/Dr. Padma Shahi

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WL =

Grossweight of aircraft where, WL is wing loading wing area

PL =

Grossweight of aircraft Where, PL is power loading Total HP of engine

9.6 Speed of aircraft: Ground speed or cruised speed, air speed (relative to air) 9.7 Weight of air craft and wheel configuration: These are important for the design of Runway strength, taxiway, apron and hanger etc. 9.8 Jet Blast: At relatively high velocities the aircraft eject hot exhaust gases. It may affect the bituminous pavement, cause uncomfort to the passenger. Jet Blast deflector or fences could be constructed. 9.9 Fuel Spillage At loading aprons and hangers, it is difficult to avoid spillage completely. 9.10 Noise: Noise affects to the surrounding communities. 10. Aviation System Planning Aviation system planning is a process aimed at translating goals and policies into programs that would guide the evolution of the aviation system. The process is a continuing one and it includes monitoring of the development of the system and the replanting of its evolution. The aviation system planning process can be applied to planning national and statewide aviation system as well as components of such system as in the case of airport planning. Components of the aviation system: • Airways • Airports • Airlines • Aircrafts • General aviation • Air passenger • Operating environment Airport system planning, however, frequently has to be carried out as part of the exercise of master planning at one or more airports within the system. The aim of the airport system planning is to determine and plan for the scope of development of individual airports within a system in accordance with a scheme which is most likely to fit the individual facilities into an optimal overall development pattern. Airport Engineering/Dr. Padma Shahi

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Level of planning: • Strategic planning examines long-term structures and determines how well various structures fit with indentified goals and objectives. A strategic plan sets out procedure to follow which will lead to an optimal long term structure. • Tactical Planning: determines short-term and medium term courses of action which best fit into overall strategic plans and goals. Furthermore, tactical plans identify the best manner of carrying out these short and medium term courses of action. Levels Strategic planning Level

Strategic planning Level

For each airport facility Strategic and tactical Planning level

Tactical and project planning level

Activities • Sets goals and objectives • Inventory of existing strategic system • Demand analysis • Postulate options or scenarios • Evaluation • Selection of future strategic system • Inventory of existing system • Scenario and demand analysis • Postulate options for the system development • Evaluation • Select optimal airport system

Planning

• • • • • • • • •

Airport master planning

Inventory of facilities Demand analysis Airport development options Option evaluations Select preferred option Select individual project Propose different project planning options Select preferred project plan Optimize execution of project

(aviation systems planning)

Airport system Planning

Project planning

10.1 Data base for airport system Planning: •

•

Traffic data: o Route and city pair specific data, including origin/destination flows. o Airport specific data o Traffic by other modes especially in short haul situations. Demand characteristics o Origin destination demand o Trip purpose distributions for cargo demands o Commodity classifications for cargo demands o General aviation activity demand

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•

•

•

Airport data o Financial results o Facilities inventories o Capacity o Temporal traffic patterns, including hourly distributions o Airlines served o Access traffic conditions o Safety records o Weather conditions o Traffic operation patterns Supply data o City pair available capacity o Schedule and fares for passengers and cargo o Load factor prevailing o Airline operating cost data Socio economic data o Economic studies for regional economic plans if available o Population and demographic characteristics and forecasts, if available o Income characteristics and consumption patterns o Foreign and tourism trade patterns

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10.2 Comprehensive Airport system analysis

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10.3 Airport Master Plan The planner's idealized concept of the form and structure of the ultimate development of the airport is contained in the airport master plan. This plan is not only the physical form of the ultimate development plan but a description of the staging of development and both the financial implications and fiscal strategies involved. Master Planning applies to the construction of new airport as well as to the significant expansion of existing facilities. Specific objectives of airport Master Plan: 1. Provide effective graphic representation of the future development of airport and future lan-use in the vicinity of the airport. 2. Establish a realistic schedule for the implementation of the development proposed in the plan, particularly for short term capital implement program. 3. Proposing an achievable financial plan to support the scheduled implementation program. 4.

Justifying the plan technically and procedurally through a thorough investigation of concepts and options of a technical, economic, or environmental nature.

5. Presenting for public consideration in a convincing candid manner, a plan which adequately addresses the issues and satisfies local and national regulations. 6. Documenting policies and future aeronautical demand and reference in municipal deliberations on spending, debt incurrence and land –use controls. 7. Setting the stage and establishing the framework for a continuing planning process. Such process would monitor key conditions and adjust plan recommendations if required by changed circumstances. 10.4 Elements of Master Plan: The FAA specifies a number of elements which are generally to be included in any master planning exercise: 1. Organization and preplanning 2. Inventory of existing conditions and issues 3. Aviation demand forecasting 4. Requirement analysis and concept development 5. Airport site selection 6. Environmental procedure and analysis 7. Simulation 8. Airport plans 9. Plan implementation

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10.5 Steps of Master Plan ICAO: 1. 2. 3. 4. 5. 6. 7. 8. 9.

Prepare a master work plan Inventory and document of existing conditions Forecast the future air traffic demand Determine scale and time phasing of facilities Evaluate existing and potential constraints Determine the relative importance of constraints and other considerations. Develop a number of master plan options Evaluate and screen all plan options Select the most acceptable and appropriate option, refining and modifying it in response to the evaluation process 10. Prepare master plan documents in final form.

11. Airport Site Selection Suitable site for airport depends upon the class of the airport. Factors to be considered for a suitable airport site are: 1. Consistency with Regional plan 2. Operational capability: airspace considerations, obstructions, weather etc. 3. Airport use: military, civil, etc. 4. Proximity to other airport: minimum spacing between two airports: • Airport for general aviation under VFR 3.2 km • For two piston aircraft VFR: 6.4 km • Piston engine IFR: 25.6 km • Jet engine aircraft: 160 km. 5. Ground accessibility: normally it should not exceed 30 minute drive form the city. It is desirable to locate airport adjacent to the highway. 6. Topography: hill top is most suitable 7. Visibility: free from fog, smoke haze etc. 8. Wind: runway orientation should be: landing and takeoff is done by heading into wind. Smoke from city and industry should not blow over the airport. 9. Noise nuisance: landing and takeoff path should not pas over the residential or industrial areas. 10. Grading, drainage and soil characteristics 11. Future development 12. availabilities of utilities from town 13. economic considerations

12. Predicting air travel demand In any travel mode, which demand is continuously increasing at a significant rate, an estimate of the magnitude of demand at future points in time is essential. However, the forecasting of future demand is a difficult and uncertain procedure, and when forecasts are incorrect, an entire transportation mode is either deficit in its ability to provide for future traffic or is suffering Airport Engineering/Dr. Padma Shahi

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from overinvestment and poor economic performance. In spite of the difficulties associated with making forecasts of air transport demand, such estimates are necessary, for the following reasons: a) To assist manufacturers in industry to anticipate levels of aircraft orders and to develop new aircraft. b) To aid airlines in their long-run planning for both equipment and personnel. c) To assist governments to facilitate the orderly development of the national and international airways system, and to aid all levels of government in the planning o f infrastructure facilities, runways, taxiways, aprons and technical air traffic control.

Figure 1 Total world passenger Traffic

Accurate forecast of air passenger and freight demand proved to be extraordinary difficult in the past, when over an extended period rapid advances in technology continued to lower the real costs of air transport to consumer. During the period 19721987, as shown in the figure, the overall world growth of scheduled passenger kilometer was at an average rate of 7.6%. Asia and the Pacific demonstrate higher than average rates, and Africa lower than average rate.

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Figure 2 Regional air passenger growth

12.1 Conventional methods of forecasting Conventionally, forecasting of future air traffic demand has been carried out at the macroscopic scale, viewing demand as a response to the overall levels of change of one or more variables. These very simple methods have been applied with reasonable success at the local, national, and international levels, in cases where rates of growth of traffic have been remarkably constant over time. Methods that have been used include judgment, surveys of expectation, trend forecasting, and base forecasting, which we now consider in turn. Judgment: under the conditions of very limited growth, a crude but effective method of forecasting is the judgment estimate by a forecaster who is close to the problem and is able to integrate and balance the factors involved in the specific situations. The chances of success diminish as the complexity of the situation increases and need for long term a forecast predominates. Use of judgment can easily result in forecasting by feeling, a procedure that is abhorrent to analytical planners. Airport Engineering/Dr. Padma Shahi

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Surveys of expectation: It is not very widely used in the survey of expectation, directed to individuals in the air transport industry who might be said to be in a position to judge future trends. By selection of broad range of interests in the selection of those surveyed, the forecaster hopes for a balanced view. A refined procedure, which has become more widely used in general transportation planning, is Delphi analysis-approaching the estimate of future by applying an iterative procedure to survey of expectation. In this procedure, experts make forecasts and then receive a feedback of results from the entire from the entire group of forecasters. After each iteration, the range of responses tends to narrow and consensus is ultimately reached. In general, however, surveys of expectation are more suitable to aggregate forecasts at the regional or national levels than to disaggregate estimates at the airport level. Trend forecasting: extensive use has been made of trend forecasting, in which the planner simply extrapolates, basing judgment on past growth figures. In short term, this technique is reasonably reliable, especially when the extrapolation procedure is carried out with modified growth rates to account for short term disturbances in secular trends. In long term, this type of extrapolation is likely to be most unreliable and is theoretically difficult to substantiate. Early trends forecasts were straight line extrapolations that were almost always too low in the rapid growth years of 1950s and early 1960s. Forecasts over the next 10 years, that is, 1960-1970 were of an exponential nature, but opinion is now more conservative, reflecting an industry consensus that curve of growth is more likely to be logistic as in the figure below.

Figure 3 The logistic growth curve

Base forecasts on ratios of National forecasts: In USA, a technique for air traffic forecasting widely used at the local level is the base forecast method, which assumes that a city's percentage of annual national passenger volumes remain relatively constant over time. Airport forecasts are obtained by step down percentages of national forecasts. However, it has serious limitations: Airport Engineering/Dr. Padma Shahi

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•

Percentages of national growth does not remain constant;

•

National forecasts have been historically incorrect,

There are two methods used in USA: Method A: 1) Determine the percentage of national enplaned passenger that the airport has attracted in the past. 2) Adjust this percentage to reflect anticipated abnormal growth trends 3) Obtain data for national passenger volume for the design year 4) Calculate step down design figure as the product of the percentage of step 2 and the national figure from step 3. Method B 1) Obtain the number of passenger per 1000 population that the airport has experienced in the past. 2) Compare the figure computed in step 1 with the number of passengers nationally per 1000 population. 3) Compute the following ration:

r=

passengers / 1000 population for airport passengers / 1000 population for nation

4) Obtain the national forecast of air passenger volumes per 1000 population for the design year. 5) From the ratio computed in step 3 and the national forecasts of step 4, calculate the local passenger volume per 1000 population. 12.2 Analytical methods of air travel demand forecasting Analytical methods endeavor to overcome the grosser errors of trend analysis in trip generation by attempting to relate the level of traffic to change in the level of a variety of causal or closely associated factors. In the case of air traffic demand, it has been found that the number of trips made by the individual traveler depends not only on a number of socioeconomic variables outside the air transport system, such as income, employment type, and family structure, but also on system based variables, including frequency and level of service. Conventional analysis of traffic demand divides the modeling procedure into four distinct consecutive steps:

Generation

Distribution

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Assignment

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Generation models indicate how many trips originate or terminate in a specific area; these models are often based on the socioeconomic characteristics of the area and nature of the transportation system. In the distribution phase, the trips are modeled as trip interchanges between specific pairs of origin and destinations, usually using some form of equilibrium model, with time or distance as the parametric impedance to travel. Modal choice models split the interchanges into those specific to individual modes; choice normally is a function of structure and nature of the transport system and the socioeconomic status of the trip maker. Assignment models indicate which route is taken by the individual traveler from a choice of all available routes. In case of air transport, the model chain has frequently been simplified to a mode specific chain of the following from: Air trip generation

Air trip distribution

This simplified chain is inadequate insofar as it assumes that air traffic generations are peculiar to the mode itself and are not subject to modal choice dependent on the nature of the competing modes. Variables for passenger demand modeling: Travel can be recognized as the product of four basic factors that must be accounted for in any realistic analysis that attempting to predict demand over time. These basic factors are as follows: • A supply of people • A motivation to travel • Resources available for expenditure on travel in terms of time and money • A transport infrastructure capable of supporting travel demand The procedure should consist the following steps for complete demand analysis: 1) Observation of past trends 2) Identification of exogenous variables that act as surrogate for basic factors causing changes in level of air transport demand. 3) A base survey collecting the socioeconomic data that describe the status of the population, nature of the area, and the technological status of the system. 4) Establishment of relationships between the predictive variables and both levels and changes in levels of air transport demand. 5) Prediction of the anticipated level of the exogenous variables in the design year 6) Prediction from the design year levels of the exogenous variables and predictive relationships of the future demand levels. The simplistic methods of prediction, such as trend forecasting, take explicit account of the first step only, and steps 2 and 6 are mixed with subjective judgment, with varying degrees of success. In the past, variables in the following areas have been used: 1) Demographic variables. Including city size and population density 2) Proximity to the largest city 3) Economic character of the city Airport Engineering/Dr. Padma Shahi

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4) Governmental activities, regulatory policies, subsidy of competing modes etc. 5) Fare levels 6) Developments in competing transport modes 7) Technological development in the aircraft industry 8) Adequacy of infrastructure provision of the air mode and competing modes 9) Urban and regional development characteristics 10) Various other imponderables (not able to be estimated) such as socio-cultural changes in the leisure and work pattern etc 12.3 Air trip generation models The analyst models directly the number of trips ends (origins and destinations). There are two principle techniques of analysis: market analysis and regression analysis. Market analysis: it assumes that an areas share of the total market remains constant over time. National demands total are estimated for the design date usually by using straight forward trend forecasting or cross classification. Regression analysis: statistical models for the demand analysis have been widely used for many years in the prediction of urban passenger transport.

12.4 Air trip distribution models The trip distribution models predicts the level of trip interchange between designated airport pairs, once the level of generation of air trip ends at the individual airports have been the gravity model. This model analog to the Newton's law of gravity, has grown from the knowledge developed in social sciences that interaction between human settlements appear to e in accord with principles that in many similar to the physical law of gravity. The gravity model in transport practice distributes Airport Engineering/Dr. Padma Shahi

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trips between city pairs according to measures of the attractiveness of cities, allowing for the impedance effects of cost, time and other facts.

Tij = Where,

kPi Pj d ijx

Tij - is travel by air passenger between cities I and j Pi - population of origin city Pj – Population of destination city dij – distance between city i and j k – a constant of proportionality x – a calibrated constant

Using as the measure of the impedance, it was found that the value of x appeared to vary from 1.3 to 1.8. using the travel cost, the following model was calibrated:

Tij =

kTiT j Cijx

Where, Ti – Total air trips generated in city i Tj - total air trips attracted in city j Cij – cost of travel between i and j K – a constant of proportionality X - a calibrated proportionality In US studies airline interaction traffic, it was found that this model could be used for cities less than 800 miles apart. For greater air trip degenerated air trip distances, the form of the model can be simplified:

Tij = k (TiT j ) p A modified gravity model was used in Canada:

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A predictive equation of a similar form was developed by former British Airport Authority for the Western European Airports Association was:

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12.5 Modal choice models As previously stated, the analytical forecasting method has frequently been used to mode-specific air trip generation that has been separately distributed. Many factors affect modal choice, such as convenience, comfort, and safety. Though such factors are often difficult to quantify, a simple method of allowing for them and for individual variability among travelers is to construct the model from parameter that reflect the degree of randomness of the traveler's choice. The generalize dcost model assumes that the traveler will usually choose the mode with the lowest generalized cost, but there is a finite probability that some other mode will be selected.

The generalized cost of any mode is the total of direct and indirect costs incurred in traveling. If there are only two alternative modes p and q then above equation is reduced as:

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13. Airport Capacity The growth in air travel is outstripping the capacity of airport and air traffic control system, resulting in increasing congestion and delay. The consequences for the air transport industry and traveling public are greater inconvenience, higher costs, declining quality of services and concerns about diminishing safety. The purpose of capacity analysis is to: • Measure objectively the capacity of various components of an airport system for handling projected passenger and aircraft flows. • Estimate the delays experienced in the system at different levels of demand. The capacity analyses make it possible for the airport planner to determine the number of runways, to identify potential configurations, and to compare alternative design.

13.1 Capacity, Demand and Delay The term "capacity" refers to the ability of a component of airfield to accommodate aircraft. It is expressed in operations (arrivals and departures) per unit of time, typically in operations per hours. Thus, the hourly capacity of the runway system is the maximum number of aircraft operations that can be accommodated in one hour under specified operating conditions. Capacity depends on a number of prevailing conditions, such as visibility, air traffic control, aircraft mix, and type of operations. Capacity should not be confused with demand. Capacity refers to the physical capability of an airfield and its components. It is measure of supply, and it is independent of both the magnitude and fluctuation of demand and the amount of delay to aircraft. Delay, however is dependent on capacity and the magnitude and fluctuation in demand. One can reduce aircraft delays by increasing capacity and providing a more uniform pattern of demand. Airport Engineering/Dr. Padma Shahi

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13.2 Runway capacity Runway capacity is normally the controlling element of the airport system capacity. There are large numbers of factors that influence the capacity of runway system: 1) Air traffic control: FAA specifies minimum vertical, horizontal, and lateral separations for aircraft in the interests of air safety. Since no two airplanes are allowed on the runway at the same time, the runway occupancy time may also influence the capacity. Example: A runway serves aircraft that land a speed at 165 mph while maintaining the minimum separation of 3 nautical miles as specified by FAA. The average runway occupancy time for landing aircraft is 25 seconds. Determine maximum arrival rate pf the airport. The minimum spacing is (3X6076 = 18228 ft.) in terms of time the minimum arrival spacing is 18228 /(165X5280/3600)= 75 sec. The maximum rate of arrival that can be served by the runway is no more than (3600/75) = 48 arrivals per hour. 2) Characteristics of demand: capacity of runway depends on aircraft size, speed, maneuverability, and braking capability, as well as pilot technique. 3) Environmental conditions: the most important environmental factors influencing capacity are visibility, runway surface conditions, winds, and noise abatement requirements. 4) The layout and design of runway system: for the airport planner, layout and design features comprise the most important class of factors that affect runway capacity. Principal factors in this class include: • Number, spacing, length and orientation of runways. • The number, locations, and design of exit taxiway • The design of ramp entrance

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13.3 Determination of runway capacities and delay a) Empirical approaches b) Queuing models c) Analytical approaches d) Computer simulation

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Table of Contents 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

Airport Layout .................................................................................................................................................. 47 Runway Orientation: ......................................................................................................................................... 47 Typical Layout of Airport ................................................................................................................................... 53 Geometric Standards for Elements of Airport ...................................................................................................... 54 Correction for Elevation, Temperature and Gradient ............................................................................................ 58 Taxiway and Apron .......................................................................................................................................... 63 Holding bays and other bypasses ...................................................................................................................... 70 Apron .............................................................................................................................................................. 71 Terminal Facilities & Space ............................................................................................................................... 77 Air traffic management...................................................................................................................................... 83 CNS/ATM System ............................................................................................................................................ 86 References ...................................................................................................................................................... 90

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1. Airport Layout The design for each airport layout is site specific, and whereas general concepts can be moved between sites, the individual aspects of each site will almost certainly result in slightly different layouts. Layout of an airport is dependent upon a number of factors the most important are:

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Number and orientation of runways Number of taxiways Size and shape of aprons The area and shape of land Topography and site soil conditions Obstacle to air navigation Required proximity of land uses within the airport boundary Surrounding land uses Timing and scale of phased development of the airport Meteorology Size and scale of airport facilities being planned

Principle facilities to be considered in an airport plan are: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21.

Runways Taxiways Passenger terminal and aprons Cargo terminal and apron Rescue and firefighting services Air traffic control tower Aircraft maintenance Long-term and short-term parking Access roads Public transport access Airport maintenance and engineering base Navaids Lighting Flight kitchens Fuel farm General aviation terminal and apron Sewage treatment and pumping station Electric sub-station Security fence and control gates Hotels Industrial uses

2. Runway Orientation: Because of obvious advantages of landing and taking off into the wind, runways are oriented in the direction of prevailing wind. Aircraft may not maneuver safely on a runway when wind contains large component at right angle to the direction of travel. The point at which this component (cross wind component) becomes excessive will depend upon the size and operating characteristics of the aircraft. Airport Engineering/Dr. Padma Shahi

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Figure 4 Maximum permissible Cross Wind Component (FAA)

Factors affecting the determination of the siting, orientation and number of runways: • • • •

•

weather, in particular the runway/aerodrome usability factor, as determined by wind distribution, and the occurrence of localized fogs; topography of the aerodrome site and its surroundings; type and amount of air traffic to be served, including air traffic control aspects; aeroplane performance considerations; and environmental considerations, particularly noise.

The primary runway, to the extent other factors permit, should be oriented in the direction of the prevailing wind. All runways should be oriented so that approach and departure areas are free of obstacles and, preferably, so that aircraft are not directed over populated areas.

Figure 5 Maximum permissible CWC (ICAO)

Head wind: direction of wind opposite to the direction of landing and takeoff • •

Takeoff: head wind provides greater lift on the wings, thus shorter length of runway is enough Landing: Headway provides a braking effect and aircraft comes to stop in a smaller length of runway.

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If landing and takeoff are done along the wind direction, it may require longer runway length. Cross wind Component: it is not always possible to obtain the direction of wind along the direction of the center line of runway, this Normal wind component is called cross wind component. And it may interrupt the safe landing and takeoff of the aircraft. VSinθ is the Cross wind Component.

θ

θ θ

Wind Coverage: The percentage of time in a year during which the CWC remains within the limit is called Wind Coverage.

• •

FAA standards for mixed air traffic wind coverage should be 95 % with the limit of 25 kmph. CWC. For busy airport, WC may be 98 -100 %

Wind Rose method: Typically wind rose is applied for the orientation of runway. Wind Rose type I: It is the graphical representation of wind data: direction and intensity. Data should be collected for the period of 5 to 10 years. Wind data average of 8 years period

Wind direction

Duration, % 6.4 -25 kmph

25 – 40 kmph

40 – 60 kmph

Total in each direction, %

N

7.4

2.7

0.2

10.3

NNE

5.7

2.1

0.3

8,1

NE

2.4

0.9

0.6

3.9

ENE

1.2

0.4

0.2

1.8

E

0.8

0.2

0.0

1.0

ESE

0.3

0.1

0.0

0.4

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SE

4.3

2.8

0.0

7.1

SSE

5.5

3.2

0.0

8.7

S

9.7

4.6

0.0

14.3

SSW

6.3

3.2

0.5

10.0

SW

3.6

1.8

0.3

5.7

WSW

1.0

0.5

0.1

1.6

W

0.4

0.1

0.0

0.5

WNW

0.2

0.1

0.0

0.3

NW

5.3

1.9

0.0

7.2

NNW

4.0

1.3

0.3

5.6

Total % = 86.5 (100 - 86.5 ) = 13.5 % of time wind intensity is less than 6.4 kmph. This period is called Calm Period.

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Wind Rose type II In this method a transparent template is prepared for determining the runway orientation. The wind data shown in the table are plotted on a wind rose by replacing the percentage in the appropriate segment of graph. On the wind rose, the circles represent wind velocity in miles per hour and the radial lines indicate wind direction. The wind rose procedure makes use of a transparent template on which three parallel lines have been plotted. The middle line represents the runway center line, and the distance between it and each of the outside lines is equal to the cross wind component.

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Figure 6 Wind rose diagram for an allowable cross wind of 15 miles per hour

Following steps are necessary to determine the best runway orientation and to determine the percentage of time that orientation conforms to the cross wind standards. a) Place the template on the rose so that the middle line passes through the center of the wind rose. b) Using the center of wind rose as a pivot, rotate the template until the sum of the percentage between the outside lines is a maximum. c) Read the true bearing for the runway on the outer scale of the wind rose beneath the centre line of the template. d) The sum of percentage between the outside lines indicates the percentage of time that a runway with the proposed orientation will conform to crosswind standards.

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3. Typical Layout of Airport

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4. Geometric Standards for Elements of Airport Standards are for: 1. Runway 2. Taxiway 3. Apron 1. Runway Parameters of runway are: i) ii) iii) iv) v) vi)

Length Width Sight distance Gradient & Change in Gradient Transverse Gradient Runway Intersection Runway Clearance

Selecting design runway length is one of the most important decisions an airport designer. The runway length determines the size and cost of the airport, and controls the types of air craft it will serve. Furthermore, it may limit the payload of the critical aircraft and length of journey it can fly. The runway must be long enough to allow safe landing and takeoff by current equipment and by future aircraft expected to use the airport. It must accommodate differences in pilot skill and variety of aircraft types and operational requirements. The following factors most strongly influence required runway length. a) b) c) d) e)

Performance characteristics of aircraft using runway length. Landing and takeoff gross weights of aircraft Elevation of airport Average maximum air temperature at the airport Runway gradient

Note: • •

Correction for elevation and temperature should be done Maximum width of landing strip: o Non instrumental runway: 150 m o Instrumental runway: 300 m

Actual length of Runways Primary runways: Except where a runway is associated with a stopway and/or clearway, the actual runway length to be provided for primary runway should be adequate to meet the operational requirements of the aeroplanes for which the runway is intended and Airport Engineering/Dr. Padma Shahi

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should be less than the longest determined by applying the corrections for local conditions to the operations and performance characteristics of the relevant aeroplanes. Both takeoff and landing requirements need to be considered when determining the length of runway to be provided and need for operations to be conducted in both directions of runway. Local conditions that may need to be considered include elevation, temperature, runway slope, and the runway surface characteristics.

Secondary runways: The length of secondary runway should be determined similarly to primary runways except that it needs only to be adequate for those aeroplanes which require using that secondary runway in addition to the other runway or runways in order to obtain a usability factor of at least 95 percent. Runways with stopways and/or clearways: When runway is associated with a stoway or clearway, an actual runway length less than that resulting from application of (primary and secondary runways) as appropriate, may be considered satisfactory, but in such a case any combination of runway, stopways or clearway provided.

Basic length of runway characte It is the length of runway under the following conditions: • • • • •

Airport altitude is at sea level Airport temperature is 15 0 Celsius Runway is level in longitudinal direction No wind is blowing on runway Aircraft is loaded to its full capacity.

Declared distances The introduction of stopways and clearways and the use of displaced thresholds on runways has created a need for accurate information regarding the various physical distances available and suitable for the landing and takeoff of airplanes. a) Take-off run available (TORA): the length of runway declared available and suitable for the ground run off an aero plane taking off.

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b) Take off distance available (TODA): provided.

the length of takeoff run available plus the length of the clearway, if

c) Accelerate stop distance available (ASDA): the length of the take-off run available plus the length of the stopway, if provided.

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d) Landing distance available (LDA): the length of runway which is declared available and suitable for ground run of an airoplane landing.

1. When a runway is not provided with stopway or clearway and threshold is located at the extremity of the runway, the four declared distances should be equal to the length of the runway as in figure A. 2. Where runway is provided with clearway, then the TODA will include the length of clearway as in figure B. 3. When runway is provided with a stopway, then the ASDA will include the length of stopway as in figure C. 4. Where a runway has a displaced threshold, then the LDA will be reduced by the distance the threshold is displaced as in figure D.

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Figure 7 Declared distances

5. Correction for Elevation, Temperature and Gradient Basic length of runway is for mean sea level, having standard atmospheric conditions. It is necessary to carry out corrections for elevation, Temperature and Gradient a) Correction for Elevation As the elevation increases, the air density reduces. It reduces the lift on the wing of the aircraft and aircraft requires greater ground speed before it can rise into the air. To achieve greater speed longer length of runway is required. ICAO recommends that the basic runway length should be increased at the rate of 7% per 300 m rise in elevation above mean sea level. Correction for temperature The rise in airport reference temperature has the same effect as that of the increase in elevation. Airport reference temperature (Tr) is defined as the monthly mean of average daily temperature (Ta) for the hottest month of the year plus one third the difference of this temperature (Ta) and monthly mean of the maximum daily temperature (Tm) for the same month of the year.

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Tr = Ta +

Tm − Ta 3

ICAO recommends that the basic length of the runway after having been corrected for elevation should be further increased at the rate of 1 % for every 1o rise of airport reference temperature above the standard atmospheric temperature (Ts) at the elevation. The temperature gradient of the standard atmospheric from the mean sea level to the altitude at which temperature becomes 15 o C is -0.0065 o C per meter. Check for total correction for elevation and temperature: It the total correction (elevation and temperature) exceeds 35% the basic runway length, these corrections should then be checked up by conducting specific studies. b) Correction for Gradient Steeper gradient results in greater consumption of energy, and longer the runway length is required for attaining the ground speed. ICAO does not recommend on this correction. FAA recommends that the runway length after having been corrected for elevation and temperature should be further increased at the rate of 20% for every 1% of effective gradient. Effective gradient is defined as the maximum difference in elevation between the highest and lowest points of runway divided by the total length of runway. ii) Width of Runway The width of a runway should not be less than the approximate dimension specified in the table below. The factors affecting the width of runway are: a) b) c) d) e) f) g) h)

Deviation of an aeroplane from the centerline at touchdown. Cross wind condition Runway surface contamination (snow, rainfall ice etc.) Rubber deposit Crab landing approached used in cross-wind conditions Approach speeds used Visibility Human factors

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Longitudinal slopes: The slopes computed by dividing the differences between the maximum and minimum elevation along the runway centerline by the runway length should not exceed: • 1 % where the code number is 3 or 4 • 2% where the code number is 1 or 2 Along no portion of a runway should the longitudinal slope exceed: •

1.25% where the code number is 4, except that for the first and last quarter of the length of the runway the longitudinal slope should not exceed 0.8%. • 1.5 % where the code number is 3, except that the first and last quarter of the length of a precision approach runway II or III the longitudinal slope should not exceed 0.8%. • 2 % where the code number is 1 or 2. Longitudinal slope changes Where slope changes cannot be avoided, a slope change between two consecutive slopes should not exceed: • 1.5 % where code number is 3 or 4; • 2% where code number is 1 or 2 The transition from one slope to another should be accomplished by a curved surface with a rate of change not exceeding: • • •

0.1 % per 30 m. (R min of 30 000) where code number is 4 0.2% per 30 m ( R min 15 000) where code number is 3. 0.4% per 30 m (R min 7 500) where code number is 1 or 2.

Sight distance Where slope changes cannot be avoided, they should be such that there will be an unobstructed line of sight from: • Any three m above a runway to all other points 3 m above the runway within a distance of atleast half the length of the runway where the code letter is C, D or E; • Any point 2 m above a runway to all other points 2 m above the runway within a distance at least half the length of runway where code letter is B; and • Any point 1.5 m above a runway to all other points 1.5 m above the runway within a distance of at least half the length of runway where the code letter is A. Distance between slope changes Undulation or appreciable change in slopes located together along the runway should be avoided. The distance between the points of intersection of two successive curves should not be less than: a) The sum of the absolute numerical values of the corresponding slope changes multiplied by the appropriate values as below: • 30 000 m where the code number is 4 • 15 000 m where the code number is 3 and • 5 000 m where the code number is 1 or 2 b) 45 m; Whichever is greater? Airport Engineering/Dr. Padma Shahi

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Figure 8 Runway visibility zone

Transverse slope To promote the rapid drainage of water, the runway surface should, if practicable, be cambered except where a single cross fall from high to low in the direction of the wind most frequently associated with rain would ensure rapid drainage. The transverse slope should ideally be: • 1.5 % where the code letter is C, D, E or F • 2% where the code letter is A or B But in any event should not be exceed 1.5 % or 2 %. As applicable, nor be less than 1 % except at runway or taxiway intersections where flatter slopes be necessary. Runway shoulder Runway shoulder must be provided to ensure a transition from the full strength pavement to the unpaved strip of runway. The paved shoulder protects the edge of the runway pavement, contribute to the prevention of soil erosion by jet blast and Airport Engineering/Dr. Padma Shahi

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mitigate foreign object damage to jet engines. Runways shoulder should be provided for a runway where the code letter is D or E and the runway width is less than 60m. Runway shoulders should be provided where the code letter is F. The runway shoulders should extend symmetrically on each side of the runway so that the overall width of the runway and its shoulders is not less than 60 m for letter E and 75 m fir code letter F. Slopes: The surface of the shoulder that abuts the runway should be flush with the surface of the runway and its transverse downward slope should not exceed 2.5 %. Runway strip: A runway strip extends laterally to a specified distance from the runway center line, longitudinally, before the threshold, and beyond the runway end. It provides an area clear of objects which may endanger aeroplanes. The strip includes a graded portion which should be so prepared as to not cause the collapse of the nose gear if an aircraft should leave the runway. There are certain limitations on the slopes permissible on graded portion of the strip. A strip should before the threshold and before the end of the runway or stopway for a distance of at least: • 60 m where the code number is 2, 3, or 4. • 60 m where the code number is 1 and the runway is an instrument one; • 30 m where the code number is 1 and runway is a non-instrument one. Width: A strip including a precision approach runway shall, wherever practicable, extend laterally for a distance of at least: • 150 m where the code number is 3 or 4 and; • 75 m where the code number is 1 or 2. A strip including non-precision approach should extend laterally to a distance of at least: • 150 m where the code number is 3 or 4; • 75 m where the cod number is 1 and 2 On each side of the centerline of the runway and its extended centerline through the length of the strip A strip including a non-instrument runway should extend, on each side of the centre line of the runway and its extended centre line throughout the length of the strip, for a distance of at least:

• •

•

75 m where the code number is 3 or 4 40 m where the code number is 2; and 30 m where the code number is 1.

Objects An object, other than equipment or installation required for air navigation purposes, situated on a runway strip which may endanger aeroplanes should be regarded as an obstacle and should, as far as practicable, be removed. Any equipment or installation required for air navigation purposes which must be Airport Engineering/Dr. Padma Shahi

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located on the runway strip should be of minimum practicable mass and height, frangibly designed and mounted, and sited in such a manner as to reduce the hazard to aircraft to a minimum.

No fixed object, other than visual aids required for air navigation purposes, shall be permitted on a runway strip: • •

•

within 77.5 m of the runway centre line of a precision approach runway category I, II or III where the code number is 3 or 4 and the code letter is F; or within 60 m of the runway centre line of a precision approach runway category I, II or III where the code number is 3 or 4; or within 45 m of the runway centre line of a precision approach runway category I where the code number is 1 or 2.

6. Taxiway and Apron Maximum capacity and efficiency of an aerodrome are realized only by obtaining the proper balance between the need for runways, passenger and cargo terminals, and aircraft storage and servicing areas. These separate and distinct aerodrome functional elements are linked by the taxiway system. The components of the taxiway system therefore serve to link the aerodrome functions and are necessary to develop optimum aerodrome utilization The taxiway system should be designed to minimize the restriction of aircraft movement to and from the runways and apron areas. A properly designed system should be capable of maintaining a smooth, continuous flow of aircraft ground traffic at the maximum practical speed with a minimum of acceleration or deceleration. This requirement ensures that the taxiway system will operate at the highest levels of both safety and efficiency.

Planning principles of taxiway: a) taxiway routes should connect the various aerodrome elements by the shortest distances, thus minimizing both taxiing time and cost; b) taxiway routes should be as simple as possible in order to avoid pilot confusion and the need for complicated instructions; c) straight runs of pavement should be used wherever possible. Where changes in direction are necessary, curves of adequate radii, as well as fillets or extra taxiway width, should be provided to permit taxiing at the maximum practical speed (see Section 1.4 and Appendix 1); d) taxiway crossings of runways and other taxiways should be avoided whenever possible in the interests of safety and to reduce the potential for significant taxiing delays; e) taxiway routings should have as many one-way segments as possible to minimize aircraft conflicts and delay. Taxiway segment flows should be analysed for each configuration under which runway(s) will be used; f) the taxiway system should be planned to maximize the useful life of each component so that future Design criteria for taxiway are given in the table below.

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Figure 9 Taxiway on apron

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Figure Stages in Taxiway system development

Taxiway Curve: Changes in direction of taxiways should be as few and small as possible. The design of the curve should be such that when the cockpit of the aeroplane remains over the taxiway centre line markings, the clearance distance between the outer main wheels of the aeroplane and the edge of the taxiway should not be less than those specified in the table below:

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Taxiway separation distances

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Rapid exit taxiways: Airport Engineering/Dr. Padma Shahi

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A rapid exit taxiway is a taxiway connected to a runway at an acute angle and designed to allow landing aeroplanes to turn off at higher speeds than those achieved on other exit taxiways, thereby minimizing runway occupancy time.

A decision to design and construct a rapid exit taxiway is based upon analyses of existing and contemplated traffic. The main purpose of these taxiways is to minimize aircraft runway occupancy and thus increase aerodrome capacity. When the design peak hour traffic density is approximately less than 25 operations (landings and take-offs), the right angle exit taxiway may suffice. The construction of this right angle exit taxiway is less expensive, and when properly located along the runway, achieves an efficient flow of traffic.

Figure. Design of rapid exit taxiway (code no 1 and 2)

7. Holding bays and other bypasses a) Holding bays: A defined area where aircraft can be held or bypassed. Figure 2-1 shows some examples of holding bay configurations and Figure 2-2 gives a detailed example of a holding bay, located at the taxi-holding position. Airport Engineering/Dr. Padma Shahi

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b) Dual taxiways. A second taxiway or a taxiway bypass to the normal parallel taxiway. Figure shows some examples. c) Dual runway entrances. A duplication of the taxiway entrance to the runway.

Figure 10 holding bay

Figure 11 by-pass

8. Apron An apron is a defined area intended to accommodate aircraft for purposes of loading and unloading passengers, mail or cargo, fuelling and parking or maintenance. The apron is generally paved but may occasionally be unpaved; for example, in some instances, a turf parking apron may be adequate for small aircraft Airport Engineering/Dr. Padma Shahi

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Types: 1. Passenger apron: The passenger terminal apron is an area designed for aircraft manoeuvring and parking that is adjacent or readily accessible to passenger terminal facilities. This area is where passengers board the aircraft from the passenger terminal. In addition to facilitating passenger movement, the passenger terminal apron is used for aircraft fuelling and maintenance as well as loading and unloading cargo, mail and baggage. Individual aircraft parking positions on the passenger terminal apron are referred to as aircraft stands. 2. Cargo terminal apron: Aircraft that carry only freight and mail may be provided a separate cargo terminal apron adjacent to a cargo terminal building. The separation of cargo and passenger aircraft is desirable because of the different types of facilities each requires both on the apron and at the terminal 3. Remote parking apron: In addition to the terminal apron, airports may require a separate parking apron where aircraft can park for extended periods. 4. Service hanger apron: A service apron is an uncovered area adjacent to an aircraft hangar on which aircraft maintenance can be performed, while a hangar apron is an area on which aircraft move into and out of a storage hangar. 5. General aviation aircraft, used for business or personal flying, require several categories of aprons to support different general aviation activities.

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Figure 12 passenger terminal apron

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General layout of apron:

The amount of area required for a particular apron layout depends upon the following factors: • • • • • • •

the size and manoeuvrability characteristics of the aircraft using the apron; the volume of traffic using the apron; clearance requirements; type of ingress and egress to the aircraft stand; basic terminal layout or other airport use (see 3.3); aircraft ground activity requirements; and taxiways and service roads.

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9. Terminal Facilities & Space Terminal area: Area other than landing, serves for other activities includes: • • •

Terminal and operational building for managerial & operational activities Vehicle parking area Aircraft service Hanger

Various facilities provided in airport terminal building: a) b) c) d) e) f) g) h) i) j) k) l) m) n) o) p) q) r) s)

Passenger and baggage handling counter Baggage claim section Enquire counter Space for handling & processing mail, cargo etc. Public Telephone booth Waiting hall for passenger & visitors Toile facilities Restaurants & Bars First aid room General store & gift store Space for newspapers Space for airport staff Weather bureau Post office Bank Custom control Security & Police Passport control Airline office

Functions of the airport passenger terminal

Airport terminal constituents one of the principle elements of infrastructure cost at the airport. The passenger terminal performs mainly three functions: a) Change of mode: few air trips are made direct from origin to destination. By their nature, air trips are mixed mode trips, with surface access trips linked at either end to the line haul air trips. These movement patterns are accommodated by passenger circulation areas. b) Processing: the terminal is a convenient point to carry out certain processes associated with air trip. These may include ticketing and checking in the passengers. This function of the terminal requires passenger processing space. c) Change of movement type: although aircraft move passengers in discrete groups in what is termed "batch movements", the same passengers access the airport on an almost continuous basis, arriving and departing in small groups mainly by bus, auto, taxi and etc. the terminal therefore functions on the Airport Engineering/Dr. Padma Shahi

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departure side as a reservoir that collects passengers continuously and processes them in batches. On the arrivals side, the pattern is reverse. To perform this function, the terminal must provide passenger holding apace.

Facilities required for Passenger terminal

The terminal acts as the transfer point between the land and air side portions of the mixed mode 'air trip' made by air passenger. The facilities can be categorized as follows: 1. Access including the land side interface The facilities include curbside loading and unloading, curbside baggage check in, shuttle services to parking lots another terminal, and loading and unloading area.

2. Passenger processing area: The area is designated for formalities associated with processing passengers. The usual facilities include airline ticketing and passenger check-in, baggage check-in, gate check-in, incoming and outgoing customs, immigration control, health control, security check up, and baggage claim.

3. Passenger holding areas, A very large portion of the passenger's time at the airport is spent outside the individual processing areas. Non-processing time, the large portion is spent in holding areas where passenger wait, in some cases with airport visitors, between periods occupied by passing through the various processing facilities. Following facilities are required: • • • •

Passenger lounges Passenger service areas: wash rooms, public telephone, post office, information desk, first aid, valet service, barber beauty parlours etc. Concessions: bars, restaurants, Observation desk and visitors lobbies: including VIP facilities

4. Internal circulation and airside interface Passenger move physically through the terminal system using the internal circulation system which should be simple to find and follow and easy to negotiate. The airside interface is designed for secure and easy boarding of the aircraft. Internal circulation is handled by corridors, walkways, people movers, and moving belts, ramps, tramways. Airside interface requirements include loading facilities such as jetways, stairs, air bridges and mobile launges. 5. Airline and support areas Although airline terminals are designed primarily for airline passengers, most of whom will be quite unfamiliar with their surroundings, the design must also cater to the needs of airline, airport, and support personnel working in terminal area. Following facilities are required: Airport Engineering/Dr. Padma Shahi

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1. Airline offices, passenger and baggage processing stations, telecommunications, flight planning documentation, crew rest facilities, air line station administration, staff and crew toilets, rest and refreshment areas. 2. Storage for wheel chairs, 3. Airport management offices 4. Governmental office and support area for staff working in customs, immigration, health, and air ssenger and traffic control, 5. Public address system, sign indicators and support areas flight information 6. Maintenance personnel offices and support areas, maintenance equipment storage. 6. Passenger and baggage flow An adequately designed airport terminal is the work of a designer who understands the various flows of passengers and baggage at a terminal. The figure below shows the typical flow of passenger and baggage.

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Terminal design concepts

The design of terminal depends upon the nature of the sir traffic to be handled at an airport. The design concepts chosen is a function of a number of factors, including the size and nature of traffic demand, number of participating airlines, the traffic split between international and domestic, scheduled, and charter flights, access modes etc. The most fundamental choice is that of centralized or decentralized processing. There are different terminal configurations.

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Terminal Space design standards (FAA)

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Level of service standards for terminal space

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Simple network analysis of the enplanement of a domestic passenger

10.

Air traffic management

The general objective of ATM is to enable aircraft operators to meet their planned times of departure and arrival and adhere to their preferred flight profiles with minimum constraints and without compromising agreed levels of safety. The ATM comprises the functions of air traffic services (ATS), airspace management (ASM) and air traffic flow management (ATFM). The air traffic services are the primary components of ATM.

Control of air traffic was almost unknown in 1944. Today, air traffic control, flight information and alerting services, which together comprise air traffic services, rank high among the indispensable ground support facilities which ensure the safety and efficient operation of air traffic throughout the world.

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Annex 11 to the Chicago Convention defines air traffic services and specifies the worldwide Standards and Recommended Practices applicable in the provision of these services. The world's airspace is divided into a series of contiguous flight information regions (FIRs) within which air traffic services are provided. In some cases, the flight information regions cover large oceanic areas with relatively low air traffic density, within which only flight information service and alerting service are provided. In other flight information regions, large portions of the airspace are controlled airspace within which air traffic control service is provided in addition to flight information and alerting services. Air travel must be safe and efficient; this requires, among other things, a set of internationally agreed rules of the air. The rules which consist of general rules, visual flight rules and instrument flight rules apply without exception over the high seas and over national territories to the extent that they do not conflict with the rules of the State being overflown. The pilot-in command of an aircraft is responsible for compliance with the rules of the air. All aircraft fly in accordance with either instrument flight rules (IFR) or visual flight rules (VFR). Under IFR, the aircraft fly from one radio aid to the next or by reference to self-contained airborne navigation equipment from which the pilot can determine the aircraft's position at all times. Aircraft flying under VFR must remain clear of cloud and operate in visibility conditions which will permit the pilot to see and avoid other aircraft. When operating under air traffic control the aircraft must maintain precisely the route and altitude that have been assigned to it and keep air traffic control informed about its position. A flight plan must be filed with air traffic services units for all flights that will cross international borders, and for most other flights that are engaged in commercial operations. The flight plan provides information on the aircraft's identity and equipment, the point and time of departure, the route and altitude to be flown, the destination and estimated time of arrival, and the alternate airport to be used should landing at destination be impossible. The flight plan must also specify whether the flight will be carried out under visual or instrument flight rules.

Air Traffic Services Objectives of air traffic services a. Prevent collision between aircraft; b. Prevent collision between aircraft on the manoeuvring area and obstructions on that area; c. Expedite and maintain an orderly flow of air traffic; d. Provide advice and information useful for the safe and efficient conduct of flights; e. Notify appropriate organizations regarding aircrafts in need of search and rescue aid and assist such organization as required. The air traffic services shall comprise three services

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1. Air traffic control services: - Aerodrome control services - Approach control services - Area control services 2. The flight information services 3. The alerting services Air traffic control service consists of clearances and information issued by air traffic control units to achieve longitudinal, vertical or lateral separation between aircraft, in accordance with the provisions set out in the Annex 11. Contingency planning is an important responsibility of all States that provide air navigation services. In the event of disruptions of air traffic services and related supporting services, States has to develop contingency planning to providing for the safe and orderly flow of international air traffic. Safety is the overriding concern of international civil aviation and air traffic management contributes substantially to safety in aviation. Annex 11 contains an important requirement for States to implement systematic and appropriate air traffic services (ATS) safety management programmes to ensure that safety is maintained in the provision of ATS within airspaces and at aerodromes. So effective coordination between ANS providers and Aerodrome plays important role to implement and maintain SMS in ATS and aerodrome.

The Area Chart — ICAO provides pilots with information to facilitate the transition from en-route phase to final approach phase, as well as from take-off to en-route phases of the flight. The charts are designed to enable pilots to comply with departure and arrival procedures and holding pattern procedures, all of which are coordinated with the information on the instrument approach charts. The Instrument Approach Chart — ICAO provides the pilot with a graphic presentation of instrument approach procedures, and missed approach procedures to be followed should the crew be unable to carry out a landing. This chart type contains a plan and profile view of the approach with full details of associated radio navigation aids and necessary aerodrome and topographical information. FUNCTIONS OF AERODROME CONTROL TOWERS Aerodrome control towers shall issue information and clearances to aircraft under their control to achieve a safe, orderly and expeditious flow of air traffic on and in the vicinity of an aerodrome with the object of preventing collisions between: - Aircraft flying within the designated area of responsibility of the control tower, including the aerodrome traffic circuits:

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Selection of runway ATC will nominate that runway for landing or take off which appears to be most suitable. ATC may specific circuit direction or turn for traffic separation requirement. ATC, whenever practicable, advise the aircraft about the wake turbulence and its hazard. priority shall be given to:  an aircraft which anticipates being compelled to land because of factors affecting the safe operation of the aircraft ( engine failure, shortage of fuel, etc.)  hospital aircraft or aircraft carrying any sick or seriously injured persons requiring urgent medical attention;  aircraft engaged in search and rescue operations; and  Other aircraft as may be determined by the appropriate authority.

The sky m ay be lim itless but not for air traffic. A s m ore aircraft fill the crow ded air routes, air traffic control concepts, procedures, equipment and rules w ill continue to evolve.

11. CNS/ATM System • • • • • • • •

Concept of Communication, Navigation and Surveillance in Aviation. Present CNS facilities used in Civil Aviation in Nepal. Limitations of existing (ground based) CNS system. Requirement for new CNS System. Historical background of FANS/New CNS/ATM System. Components of new CNS/AMT System. Benefits of new CNS/ATM System. Status of CNS/ATM Implementation in Nepal.

Concept of Communication, Navigation and Surveillance:The process of getting an air craft safely and efficiently to its destination has been classified by ICAO into three functions : Communication:- is the exchange of voice and data information between the aircraft and air traffic controllers or flight information centers. • Contd…. Navigation:- Navigation pinpoints the location of aircraft for the crew.

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Surveillance:Surveillance pinpoints the location of the aircraft for Traffic Controller. It includes the communication of navigation information form Aircraft to Air traffic controllers, which facilitates the continuous mapping of the relative position of Aircraft. • Present CNS Facilities In Nepal A) Communications :i) HF Communications : - Domestic point-to-point communication -Domestic Air/Ground Communication. - International Air/Ground Communication. ii) VHF Communication: - VHF A/G Communication - ATIS - VHF RCAG Communication ii) UHF Communication: - UHF link between TIA and Phulchoki Station. - UHF link between Nepalgunj and Chamire Station. iv) Satellite Communication: - VSAT Link Between Kathmandu and Beijing. a) KTM-Beijing (data communication) b) KTM-Lhasa (voice communication) V) Others: - N.T. lease line for AMSS. - N.T. lease line for ATM direct speech. B) Navigation:i)

NDB’s + Locators – (23 nos.)

ii)

VOR (6 nos.)

iii)

DME (7 nos.)

iv)

Marker beacon

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V)

Visual Navigation Aids a) Approach lightings b) PAPI

C) Surveillance :i)

Voice position reports (procedural)

ii)

ASR/SSR System

• AIR TRAFFIC MANAGEMENT A general objective of ATM is to enable aircraft operators to meet their planned times of departure and arrival and adhere to their preferred flight profiles with minimum constraints without compromising agreed levels of safety. (ICAO Doc. 9583, AN -CONE/10) Air Traffic Management The FANS described ATM as consisting of ground and air parts which are needed to ensure the safe and efficient movement of aircraft during all phases of flight. It means a close integration between both parts through well-defined procedures. • The airborne part of ATM consists of the functional capability which interacts with the ground part to attain general objectives of ATM. • Elements of ATM • Limitations of Existing CNS System: i) The line of sight propagation of current system and/or the accuracy and reliability constraints resulting from variability in the propagation characteristics. ii) Difficulty in implementing of present CNS system in large parts of the world. iii) The limitation of voice communications and lack of digital air-to-ground data interchange systems. • Limitations of Current CNS System In Communication: • •

i) HF Noisy and Uncertain ii) VHF – Poor Coverage iii) Lack of Air Ground Data Link. In Navigation: i) Limited coverage and accuracy of NDB/VOR/DME. ii) Difficult to install in remote areas- mountain, desert, jungle. iii) FM interference, limited channel capacity of ILS. iv) Site problem of ILS. In Surveillance: i) Difficult to site RADAR ii) No surveillance in oceans iii) No adequate PSR/SSR to cover entire airspace. iv) Reduced separation – where no RADAR coverage Airport Engineering/Dr. Padma Shahi

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• Need for Change i) Increased growth in Air Traffic. ii) Limitation of current systems. iii) New technologies provide solutions. iv) Global consistency in CNS/ATM is essential. • FANS – MILESTONES A special committee on Future Air Navigation Systems (FANS) established by ICAO council at the end of 1983. •

FANS Phase-I committee (July 84-December 88) - Developed Global concept of new CNS/ATM system.

•

FANS Phase-II committee (July 89-October 93). - Prepared a “Global Coordinated Plan” for the transition to new CNS/ATM System. - CNS/ATM cost/benefit analysis in 1993.

• 10th Air Navigation Conference in September 1994 accepted the recommendation of FANS committee. • The annual DGCA conference of Asia/Pacific Region endorsed the plan and encouraged early implementation. What are the Main Features of CNS/ATM System ? • Mix of satellite - and - ground based systems. • Global coverage • Seamless • Interoperable system • Use of air/ground data link • Employ digital and satellite technologies • Various levels of automation CNS Components CNS/ATM System Elements • Benefits of CNS/ATM System 1) Maintain or enhance the existing level of SAFETY. 2) More effective use of AIRSPACE and AIRPORT capacity. 3) The provision of communication, Navigation and Surveillance in a more cost effective manner: and 4) The global provision of CNS in a more uniform manner. Communication Benefits: i) ii) iii)

Eases communication channel congestion. Reduces communication errors. Reduces work-load of ATCs and Pilots.

Benefits in Navigation: i) ii) iii)

Air crafts can obtain highly precise position information on a global basis. Four dimensional navigation is possible. Investment on ground-based navigation equipment and maintenance cost will

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iv) Concept of RNP and Area Navigation Benefit in Surveillance: i) ii) iii) iv) v)

will be materialized.

Air traffic control is improved in the airspace where radar surveillance has not been possible. Air craft separation is reduced in the airspace without radar coverage. The freedom in selecting optimum flight route is enhanced. More efficient surveillance of aircraft and airspace will be possible. Globally unified surveillance service becomes possible allowing more effective aircraft operation.

ATM Benefits: i) ii) iii) iv) v) • i) ii) iii) iv) • i) ii) iii)

The safety of aircraft operation is enhanced. Regularity of flight is enhanced, reduction in flight delays and cancellation. More efficient airspace is promoted. Establishment of optimum flexible flight route becomes possible. Work load of ATCs and Pilots reduced. CNS/ATM Benefits to Airlines Reduced mix of avionics will lead to reduced life cycle cost. Reduction in number of navigation systems will result in lower weight and hence increased fuel efficiency. Greater airspace capacity will lead reduced flight delays. More efficient routine of aircraft will lead to reduced fuel burn. CNS/ATM Activities in Nepal ICAO CNS/ATM in country workshop in Nepal (23-26 May, 1994). Formation of CNS/ATM project at DCA Nepal in 1995. Transformation of necessary reference points and navigation aid coordinates into WGS-84 system of all the airports in Nepal. iv) Preparation of National CNS/ATM Transition Plan for the period of 10 years. v) Preparation of GPS based IFR en-route and Non-precision Approach (NPAs) procedures for 9 airports. vi) Human resources development in the

field of new CNS/ATM system.

a) inhouse interaction programmes on various topics of CNS/ATM. b)CAAN’s participation in various

ICAO’s CNS/ATM meetings, seminar, workshop etc.

12. References 1. 2. 3. 4. 5. 6. 7.

Norman Ashford, Paul H. Wright; Airport Engineering Third edition, John Wiley & Sons inc. 1992 Aerodrome Design Manual. Part 1 Runways; third edition 2006, International Civil Aviation Organization Aerodrome Design Manual. Part 2 Taxiways, Aprons and Holding Bays; fourth edition 2005, International Civil Aviation Organization International Standards and Recommended Practices, Annex 14 to the convention on International Civil Aviation; Volume I Aerodrome Design and Operation fifth edition 2009. S. K Khanna, M. G. Arora, S. S. Jain, Airport Planning and Design. Sixth edition 1999. New Chand & Bros, Roorkee. Civil Aviation Report, 2009-2011, Civil Aviation Authority Nepal Dec. 2010. Presentation slide by Dr. Punya raj Shakya

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8. 9.

Presentation slides by Mr. Sanjeev Gautam "Air Traffic management" Presentation Slides by My Sanjeev Kathayat "Communication Navigation and Surveillance"

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