Airport Engineering

What means by AIRPORT
• Air transport is the fastest mode of transportation
aircraft flying at more than 300 km p.h. to a modern
speed is nearly 3 times the speed of sound.
• An airport is a facility where passengers connect
from ground transportation to air transportation.
• An airport is a location where aircraft such as
airplanes, helicopters take off and land.
• Aircraft may also be stored or maintained at an
airport.
• An airport should have runway for takeoffs and
landings, buildings such as hangars and terminal
buildings.

What means by AIRPPORT
• An airport is a location where aircraft such as
airplanes, helicopters take off and land.
• Aircraft may also be stored or maintained at an
airport.
• An airport should have runway for takeoffs and
landings, buildings such as hangars and terminal
buildings.

advantages of air transport
• Accessibility: The air transport can reach the otherwise
inaccessible areas with other modes of transport and such
areas can be economically developed with air transport only.
• Continuous journey: The aeroplanes can fly over both,
namely, land and water. They also do not require any artificial
track as in case of railways and roadways. Thus, it grants the
facility of a continuous journey over long distances.
• Emergency use: The air service can be used for destroying the
pests by aerial spray of the chemicals. It is also extremely
useful in case of floods for dropping food packets to the
affected people and for observing the area to access the
gravity of situation.
• Saving in time: It has resulted in a tremendous saving in t
ravel time because of high speeds of aeroplanes.

disadvantages of air transport
• Flight rules: There are certain rules which are framed by the
concerned authorities and these rules are to be strictly
observed for the smooth working of air transport.
• Operating expenses: This mode of transport proves to be
expensive because heavy investments are required for the
construction of aeroplanes, airports, repair shops,
metrological stations, etc. and special training is to be given to
the pilots. The number of passengers travelling by air as well
as the quantity of cargo that can be accommodated is the
smallest as compared to other means of trains and hence, the
fares are the highest.

disadvantages of air transport
• Safety: The accidents of aeroplanes are peculiar and alarming
in nature. It has led to the psychological fear among
passengers about the safety in air travel. It has there become
difficult to encourage the general public to travel air and to
make them air-minded, especially in less advanced countries.
• Weather conditions: This mode of transport can operate only
under favorable climatic conditions. For instance, landing and
taking off operations of aircraft will be totally inconvenient
during foggy days.

AIRPORT TERMINOLOGY
• Aerodrome: Any defined area on land or water (including any
buildings, installations and equipment) intended to be use for
the arrival and departure of an aircraft is called aerodrome It
may be provided with the facilities for shelter and repair
aircraft and also for processing of passengers, baggage, mail
and cargo. It may not necessarily be used for all scheduled air
flight Sometimes the term aerodrome is used to mean an
airport.
• Aeroplane: An aeroplane is a power-driven heavier-than-ai(
flying machine-with fixed wings. It derives its lift in
atmosphere chiefly from the aerodynamic reactions on its
surfaces.

AIRPORT TERMINOLOGY
• Airfield: An airfield is an area which is used for landing an
take off of an aircraft. It may or may not be provided with
facilities for convenience of passengers and for shelter, repair
and servicing of aircraft.
• Apron: It indicates a defined area of the airport to
accommodate aircrafts for loading and unloading of cargo and
passengers, parking, refueling, etc. It is usually paved and is
located in front of the building or adjacent to hangars.

AIRPORT TERMINOLOGY
• Cargo: The term cargo is used to indicate the freight, other
than passengers, baggage and mail, which is carried by a
transport aircraft.
• CTOL: The term CTOL is used to mean the conventional
takeoff and landing.
• Hangar: The large shed erected at the airport for the purpose
of housing, servicing and repairing of aircrafts is known as
hangar.
• Runway: It is defined as a long and comparatively narrow
strip of land which is selected or prepared for the landing and
take off of aircraft along its length. It is usually paved except
for small aerodrome.

AIRPORT TERMINOLOGY
• Taxiway: A defined path on a land aerodrome, selected or
paved for the use of taxiing aircraft to and from the runway
and loading apron is known as taxiway.
• Terminal area: The portion of the airport other than the
landing area is known as terminal area and it includes
terminal building, aircraft apron, cargo storage building,
hangars, automobile parking area, etc.
• STOL: It indicates short take off and landing.

London Heathrow Airport – United Kingdom

AIRPORT SITE SELECTION
Following considerations will also be applicable in the case of
expansion of the existing airports.
• Atmospheric and meteorological conditions
• Availability of land for expansion
• Availability of utilities
• Development of the surrounding area
• Economy of construction
• Ground accessibility
• Presence of other airports
• Regional plan

• Soil characteristics
• Surrounding obstructions
• Topography
• Use of airport.

• Atmospheric and meteorological conditions: The presence of
fog, haze and smoke reduces the visibility and the poor
visibility lowers the traffic capacity of an aircraft. The fog has
a tendency to settle into areas where there is little wind. The
lack of wind is caused by the topographical features of the
surrounding locality. In a similar way, the smoke and haze are
present at sites very near to the large industrial areas.
• Availability of land for expansion: The field of aviation is
expanding day by day. It is therefore necessary to acquire land
in advance or to be able to acquire sufficient real estate in the
future for expanding the airport. As the volume of traffic
increases, it will be necessary to lengthen the runways, to
provide additional support facilities and to expand the
terminal facilities

• Availability of utilities: An airport, especially a large one, has
to be provided with the utilities like water, electric power,
telephone, sewer, etc. For electric power, most of the major
airports provide their own generating plants to be used in
emergencies.
• Development of the surrounding area: The study of the type of
development of the surrounding area is very important
because the airport activities, particularly from the standpoint
of noise, are often quite objectionable to the neighbors of the
airport.

• Economy of construction: It is clear that if alternative sites are
available and equally well-suited, the site which is more
economical to construct should be given preference. The sites
having waterlogged areas or reclaimed lands are very costly
to develop than those of natural ground. The uneven terrain
requires much more grading than flat or even terrain. The
availability of local construction materials may also have a
significant impact on the cost of the project.
• Ground accessibility: The airline passenger is interested in
overall door-to-door time than just in the portion in the air.
The location of airport at a considerable distance from the
centre of population may cause great inconvenience to the
users. All modes of transport should be considered for an easy
ground access to the airport.

• Presence of other airports: The airports should be located at a
sufficient distance apart. This is necessary to prevent the
aircrafts which are maneuvering for a landing at one airport
from interfering with the movements of the aircrafts at other
airports. The minimum distance between the adjacent
airports will depend upon the volume and type of air traffic,
operating facilities, etc.
• Use of airport: The airport site is decided also by the use of
airport i.e., civil or military. In case of an emergency like war,
the civilian airports are taken over by the military. It is
therefore necessary to see that the airport site grants natural
protection from possible air attacks during war.

Runway Design
• In general, the arrangement of the runways and the
connecting taxiway should comply with the following
conditions:
• to avoid delay in the landing, taxiing and take off operations
and to cause the least interference in these operations;
• to grant the shortest taxi distance possible from the terminal
area to the ends of runways;
• to make provision for adequate taxiways so that the landing
aircraft can leave the runways as quickly as possible and
follow routes as short as possible to the terminal area; and
• to provide adequate separation in the air traffic pattern.

Runway Orientation
Preliminary information required: It is necessary to collect
following data before deciding the orientation of the runway:
• maps of the area in the vicinity of the airport showing
contours at suitable intervals; and
• records of direction, force and duration of the wind in the
vicinity and fog characteristics of the area for as long a period
as possible.

Runway Orientation
Head Wind: The runway is usually oriented in the direction of
the prevailing winds. The head wind indicates the wind from
the opposite direction of the head or nose of the aircraft while
it is landing or taking off. The orientation of runway along the
head wind grants the following two advantages:
• (i)During landing, it provides a breaking effect and the aircraft
comes to a stop in a short length of the runway.
• (ii) During take off, it provides greater lift on the wings a
aircraft.

Runway Orientation
• Cross wind component: It is not possible to get the direction
of opposite wind parallel to centre line of throughout the year.
For some period of the year at least, the wind may blow
making some angle Ɵ with the direction of the centre-line of
the runway length as shown in fig. 4-1.

Runway Orientation
• If V kmph. is the velocity of the inclined opposing wind, its
component V sin Ɵ which is normal to the centre-line of the
runway length is called the cross wind component. If this
component is in excess, it will interrupt the safe landing and
take off operations
• The orientation of the runway should therefore be such that
this component is kept to a minimum. For light and medium
weight aircrafts, the cross wind component should not exceed
25 kmph.
Wind coverage: The percentage of time in a year during which
the cross wind component remains within the limit of km.p.h.
is called the wind coverage of the runway. The orientation the
runway should be such that the minimum wind coverage
about 95% is obtained.

Wind Rose Diagram
• Wind Rose: For the Airport, the average wind data of 5 to 10
years period are collected and represented graphically in the
form of chart known as wind rose. The study of wind rose
diagram helps in determining the most suitable orientation of
the runway and also useful for estimating the runway
capacity.

Wind Rose Diagram
• Type I wind rose: Fig. 4-3 shows the wind rose diagram of s
type. The radial lines indicate the wind direction and each
circle represents the duration of wind to a certain scale. From
the wind data of table 4-1, the total percentage of wind
blowing in north is 6.10 and accordingly, this point is marked
along north direction. Similarly, all other values are plotted
and then joined by the straight lines. The best direction of
runway is indicated along the direction of the longest line on
the wind rose diagram. In fig. 4-3, WNW-ESE is the best
orientation for the runway. This type of wind rose does not
consider the effect of the cross wind component.

Wind Rose Diagram
• Type II wind rose: From the wind data of table 4-1, it is
observed that the percentage of time during which the wind
velocity is less than 6 km p.h. works out to (100 — 88) = 12.
This period is called the calm period and it does not influence
the operations of landing and take off because of low wind
velocity. Thus, the wind velocities below 6 km p.h. have no
effect on the fixing of orientation of a runway.

Uses of Wind Rose Diagram
• The concentric circles with radii corresponding to 6, 25, 50
and 80 km p.h. to some scale are drawn. Thus, each circle
represents the wind velocity to some scale.
• The recorded duration of winds and expressed as percentage
are shown for each cardinal direction in the sector pertaining
to that direction. It may be noted that the cardinal direction is
central to its sector. Taking the wind data for N direction, the
duration of 6-25, 25-50 and 50-80 km p.h. wind velocities are
shown in 3 pertinent parts of the N direction sector as 4.6, 1.4
and 0.1%. Similarly, for NNE direction, the durations in the
sector of NNE direction are shown as 3.4, 0.75 and 0.00%. The
durations of wind velocities are thus shown in all the sectors
to complete the wind rose diagram.

• Fig. 4.4 showing direction, duration and intensity of wind

• A transparent rectangular template or paper strip is taken. Its
length should be slightly greater than the diameter of the wind
rose diagram and its width should be greater than twice the
allowable cross wind component i.e. (2 x 25) = 50 km p.h. The
scale for cross wind component should be the same as that of
the concentric circles of the wind rose diagram. Along the
centre of the length of this template, a line is marked
corresponding to the direction of runway. The two parallel
lines, one on either side of the centre-line, is drawn at a
distance equal to the allowable cross wind component i.e. 25
km p.h. from the centre-line. In other words, the two parallel
lines are 50 km p.h. away from each other.

• The wind rose diagram is fixed in position on a drawing board. A
hole is drilled in the centre of the template and it is placed on the
wind rose diagram such that its centre lies over the centre of the
wind rose diagram. In this position, the template is fixed by a pin
passing through its centre so that the template can rotate about
this pin as axis.
• The template is rotated and is placed along a particular
direction. In this position of the template, the duration of 6-25,
25-50 and 50-80 km p.h. winds are read for the cardinal
directions lying between the two extreme parallel lines marked
on the template. The sum of all these durations is expressed as
the percentage and it gives the total wind coverage for that
direction.

• The template is then rotated and is placed in the next
direction. The total wind coverage is calculated and the
process is repeated for all the directions.
• The direction which gives the maximum wind coverage is the
suitable direction for the orientation of the runway.

Following points should be noted:
• If the extreme parallel lines on the template cut some of the
three significant parts of a sector for a cardinal direction, the
values of the truncated portions of these parts lying inside the
parallel line should be found by eye estimation. This is done
on the assumption that the full part represents the percentage
of duration marked on it.
• The maximum wind coverage of a runway should be 95% on
the assumption that the calms are 5%. If a single runway is
not sufficient to provide the necessary coverage, two or more
number of runways should be planned to get the desired
coverage.

• If proper wind data for an entirely new location are not
recorded, the study of nearby measuring stations may be
made. If the surrounding area is fairly level, the records of
these stations may indicate the winds at the site of the
proposed airport. If the area is however hilly, the wind pattern
is often dictated by the topography and it will prove
dangerous to utilize the records of stations situated some
distance away from the site. In such cases, it will be advisable
to study the topography of the region at least for one year and
correlate the observations from the information gathered
from the old residents of the locality.

Runway Length
• Normal landing: As shown in fig. 4-5, the aircraft should
come to a stop within 60 per cent of the landing distance
assuming that the pilot makes an approach at the proper
speed and crosses the threshold of the runway at a height of
15 m. The beginning of the runway portion to be used as
landing is known as the threshold. The runway of full strength
pavement is provided for the entire landing distance

Runway Length
• Normal take off: The take off distance (TOD) must be, for a
specific weight of aircraft, 115 per cent of the actual distance
the aircraft uses to reach a height of 10.5 m, as shown in fig. 4-
6. The distance to reach the height of 10.5 m should be equal
to 115 per cent of the lift-off distance (LOD).

Runway Length
• Stopping in emergency: For the engine failure case, the TOD
is the actual distance required to reach a height of 10.5 m with
no percentage applied. In case of an engine failure, sufficient
distance should be available to stop the airplane rather than
continue the take off. This distance is known as the accelerate-
stop distance, as shown in fig. 4-7.
• The stopway is defined as a rectangular area at the end of
runway and in the direction of take off. It is a paved area in
which an aircraft can be stopped after an interrupted take off
due to engine failure. Its width is at least equal to the width of
runway and the thickness of pavement less than that of the
runway, but yet sufficient to take the load of aircraft without
failure. The clearway should not be more than one-half the
difference between TOD and LOD.

Correction to basic runway length
• Correction for elevation: As per the recommendation of
ICAO (International Civil Aviation Organisation), the basic
runway length should be increased at the rate of 7 per cent
per 300 m rise in elevation of airport above the mean sea
level. This correction is required because the air density
reduces as the elevation increases which in turn reduces the
lift on the wings of the aircraft. Thus, the aircraft will require
more ground speed to rise to the air and for achieving more
speed, the longer length of runway will be required

• Correction for temperature: The rise in airport reference
temperature has the same effect as that of the increase in its
elevation above mean sea-level. After the basic length is
corrected for the elevation of airport, it is further increased at
the rate of 1% for every 1°C rise in airport reference
temperature above the standard atmospheric temperature at
that elevation.

• where T1 = monthly mean of the average daily
temperature for the hottest month of the year
• T2
= monthly mean of the maximum daily
temperature for the same month.
• The standard temperature at the airport site can be
determined by reducing the standard mean sea-level
temperature of 150
C at rate of 6.5°C per thousand metre rise
in elevation.
• Note: The ICAO recommends that if the total correction for
elevation plus temperature exceeds 35% of the basic runway
length, the specific studies at the site by model tests should be
carried out.

• Correction for gradient: The maximum difference in
elevation between the highest and the lowest points of
runway divided by the total length of runway is known as the
effective gradient. According to FAA (Federal Aviation
Administration) of U.S.A., the runway length after being
corrected for elevation and temperature should further be
increased at the rate of 20% for every 1% of the effective
gradient.

Example
Q.1 Calculate the actual length of the runway from the following
data:
Airport elevation : R.L. 100
Airport reference temperature : 28°C
Basic length of runway : 600 m
Highest point along the length : R.L. 98.2 Lowest point along the
length : R.L. 95.2.

Example
Applying correction
For each 1% effective

Design of Taxiway
• The main function of taxiways is to provide access from the
runways to the terminal area and service hangars. It is evident
that the speed of aircraft on the taxiway will be much less than
that on the runway at the time of landing or take off. The
standards for the taxiway design and construction will
therefore not be as rigorous as for the runway.

Geometric Standard for Taxiway
Following eight elements of the geometric standards for
• Length of taxiway: The length of a taxiway depends upon the
distance between the apron and entry end or exit end of the
runway. The limiting length of the taxiway is not
recommended by any organization. But to save fuel
consumption, it should be as short as practicable.
• Longitudinal gradient: If the longitudinal gradient is steep,
there will be more consumption of fuel. The maximum
longitudinal gradients recommended by the ICAO are as
follows:
For A and B types of airport 1.5%
For C, D and E types of airport 3%.

• Rate of change of longitudinal gradient: The available sight
distance on the pavement is affected by the rate of change of
longitudinal gradient. The maximum rates of change of slope
for 30 m length of vertical curve are recommended by the
ICAO as follows:
• For A, B and C types of airport 1%
• For D and E types of airport 1.2%.

• Sight distance: The speed of the aircraft on the taxiway is
lower than its speed on the runway. Hence, the smaller values
of sight distance will be sufficient on the taxiway. With respect
to the sight distance, the recommendations of the ICAO are as
follows:
• For A and B types of airports, the surface of the taxiway
should be seen for a distance of 195 m from a point 2.10 m
above the taxiway.
• For C, D and E types of airports, the comparable dimensions
are 300 m and 3 m.

• Transverse gradient: For quick disposal of the surface water,
it is necessary to provide the transverse gradient for the
taxiway. The ICAO recommends the following maximum
transverse gradients:
For A, B and C types of airport' 1.5%
For D and E types of airport 2%.

Radius of curve should be such that a minimum distance of 6 m is
maintained between the nearby main gear and edge of
pavement.
where
R = radius of centre-line of taxiway in m
W = wheel base of aircraft in m
T = width of taxiway pavement in m
S = distance between point midway of the main gears and the
edge of taxiway pavement in m.

• Turning radius: the circular curve of large radius is most
suitable
• R = radius of curve in m
• V = speed of aircraft in km p.h.
• f = coefficient of friction between the tyre and pavement
surface (usually assumed as 0.13).
• Min value of radius of curvature is taken as 120 m &180 m for
supersonic jet planes.

DESIGN OF EXIT TAXIWAYS
• Angle of turn: Total angles of turn of 30° to 45° can be
negotiated in a satisfactory manner. The smaller angles are
preferable because the length of the curved path is reduced,
sight distance is improved and less concentration is required
on the part of the pilots.
• Compound curve: It is necessary to provide a compound
curve for high turn-off speeds of 65 to 95 km p.h. It minimizes
the tyre wear on the nose gear and is relatively easier to
establish it in the field. Its shape is similar to that of a spiral.

R1
= Radius of entrance curve
R2
= Radius of central curve
L1
= Length of entrance curve
L2
= Length of central curve.
Lengths L1
and L2
: The values of L1
and L2
can be obtained by using the following
equations:
The value of constant C is 0.39 and D2
is the deflection angle of the central curve.

• Stopping distance: It is necessary to provide sufficient
distance to comfortably decelerate an aircraft after it leaves
the runway.
The average deceleration rate is usually taken as 1 m/sec2
.
• Turning radius: The turning radius for smooth and
comfortable turn is calculated by

LOADING APRONS
• The paved area adjacent and in front of the terminal building
is known as the apron and it is used for loading and unloading
of the aeroplanes as well as for fuelling and minor servicing
and check up of the aeroplanes.
• The aeroplanes are berthed on the aprons before they are
loaded and unloaded. Hence, the loading apron is also known
as the parking apron. It is desirable to provide cement
concrete pavement for the aprons to resist the effects of jet
blast and fuel spillage.
• The dimensions, of the loading apron depend upon the
number of loading positions or gate positions required, the
size of aircraft and the parking system to be adopted.
Generally a clearance of 7.5 m is provided between the
aircrafts parked on the adjacent aircraft stands.

Planning Consideration of terminal building
• Centralized system: In this system, all the passengers,
baggage and cargo are routed through a central location and
then passed on to the respective aircraft positions. This
system is convenient when the aircraft parking area is within
a walking distance of 180 m. It also proves to be economical
due to the fact that many of the common facilities may be used
to serve a large number of aircraft gate positions. Fig. 6-1
shows primary and secondary stages of the centralized
system.
•

• Decentralized system: In this system, the passenger facilities
are arranged in smaller units and repeated in one or more
buildings. Each unit is arranged around one or more aircraft
gate positions and it serves the passengers using those gate
positions. All airline functions are carried out adjacent to the
departing plane. This system proves to be uneconomical when
the number of gates required by the individual airliner at one
airport exceeds six or so. Fig. 6-2 shows the decentralized
system.
•

IMPORTANCE OF AIR TRAFFIC CONTROL
• It avoids the possibility of occurrence of the accidents in the
air.
• It grants the economic and efficient utilization of the aircraft
and the airports.
• It guides the aircraft to their destinations safely and speedily.
• It increases the confidence of the passengers using the facility
of air travel.
• It separates the aircraft to a safe distance during their flight
both vertically as well as horizontally.

AIR TRAFFIC CONTROL(Navigation) AIDS
• En route aids or airway aids: During the flight from one
airport to another, the following en route aids or airway aids
are available to the pilot of the aircraft:
• Air route surveillance radar
• Air to ground communication
• Airway beacon
• Direction finder
• Distance measuring equipment
• Low/medium frequency radio range
• Marker beacon
• Tactical air navigation
• Very high frequency Omni-directional range.

• Air route surveillance radar: The long-range radars are installed along the
airways to keep a watch on the aircraft. The word radar is an abbreviation
to denote radio detection and ranging. The controller gets the picture of
each aircraft on the radar screen and he is able to decide the exact position
of the aircraft. The effective range of a radar is about 200 km.
• Air to ground communication: The flight instructions and other relevant
data will be conveyed to the pilot from the ground along the entire length of
the airway through FSS (Flight Service Station) and ARTCC(Air Route
Traffic Control Centers).

Airport Engineering

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