AIRPORT ENGINEERING

RUNWAY

A runway is a strip of land at an airport on which aircraft can take off and land and forms part of the maneuvering area.

RUNWAY ORIENTATION

Runway is usually oriented in the direction of prevailing winds. The head wind i.e the direction of wind opposite to the direction of landing & take-off, provides greater lift on the wings of the aircraft when it is taking off. As such the aircraft rises above the ground much earlier & in a shorter length of runway. During landing the head wind provides a braking effect & the aircraft comes to a stop in a

smaller length of runway. Landing & take-off operations, if done along the wind direction would require longer runway.

RUNWAY ORIENTATION

The orientation of the runway is an important consideration in airport planning and design

Ideally, all aircraft operations on a runway should be conducted against the wind

Wind conditions vary from hour to hour thus requiring a careful examination of prevailing wind conditions at the airport site

Head Wind

In aerodynamics, a headwind is a wind that blows against the direction of travel of an object. A headwind reduces the object's speed and increases the time required to reach its destination. The opposite wind is a tailwind.

Cross Wind Operations

Wind conditions vary from hour to hour

If the direction of the wind is at an angle with the center line of runway, its component along the direction of runway will be V cos and that normal to the runway center line will be V sin

V is wind velocity

All aircraft have maximum demonstrated cross wind components

Runway

Wind vector

Crosswind Component

Crosswind Component may interrupt in the safe landing and takeoff of the air crafts

Max. permissible Crosswind Component depends on

Size of the aircraft

Wing configuration

Wind coverage :- the percentage of time in a year during which the Crosswind Component remains within the limits

Wind rose

Wind data: Direction

Duration

Intensity

Wind Rose is a graphical way of analyzing data that is related to wind direction.

Type I: direction & duration

Type II: direction, duration & Intensity

Type I

Type I

Change in direction of runway

Obstruction

Excessive grading

Noise nuisance

Basic runway length

Assumed conditions:

Airport altitude is at sea level (7 % per 300m)

Temperature at the airport is standard (150 C)

Runway is levelled in the longitudinal direction

No wind is blowing on runway

Aircraft is loaded to its full loading capacity

There is no wind blowing enroute to the destination.

Enroute temperature is standard

Basic runway length

Normal landing case

Normal take off case

Engine failure care

Jet engine: 3 cases

Piston engine: 2 cases

Correction for elevation, temperature & gradient

Correction for elevation (increase 7% per 300m)

Correction for temperature(increase 1% per 10

C)

Check for the total correction for elevation plus temperature (max 350 C)

Correction for gradient (20% increase for 1 % effective gradient)

Airport classification

ICAO (International Civil Aviation Organization) classification

A to E : based on runway length (A type- longest-Min 2100 m and E type- shortest runway- Min 600m)

1 to 7 : based on ESWL (1 to 7, 1 type- maximum ESWL)