The performance data for

landing Landing is the last part of a flight, where a flying animal, aircraft, or spacecraft returns to the ground. When the flying object returns to water, the process is called alighting, although it is commonly called "landing", "touchdown" or " spl ...

aircraft An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...

can be obtained from the aircraft's flight manual or pilot's operating handbook. It will state the distance required to bring the aircraft to a stop under ideal conditions, assuming the aircraft crosses the

runway In aviation, a runway is an elongated, rectangular surface designed for the landing and takeoff of an aircraft. Runways may be a human-made surface (often asphalt concrete, asphalt, concrete, or a mixture of both) or a natural surface (sod, ...

threshold at a height of 50 ft, at the correct speed. The actual landing performance of an aircraft is affected by many variables which must be taken into account.

Factors affecting landing performance

Weight

The weight of an aircraft is the primary factor that determines the landing distance required by an aircraft. An increase in weight increases the

stall speed In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack exceeds its critical value.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', p. 486. Aviation Supplies & Academics, 1997. ...

of the aircraft. Therefore, the landing approach speed increases as the aircraft's weight increases. The

kinetic energy In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Rober ...

() that has to be dissipated to stop an aircraft is a function of the mass of the aircraft and the square of its speed at touchdown. The kinetic energy increases significantly as an aircraft's weight increases, and the brakes have to absorb this greater energy, increasing the landing roll of the aircraft.

Density altitude

An increase in

density altitude The density altitude is the altitude relative to standard atmospheric conditions at which the air density would be equal to the indicated air density at the place of observation. In other words, the density altitude is the air density given as ...

causes the

True Airspeed The true airspeed (TAS; also KTAS, for ''knots true airspeed'') of an aircraft is the speed of the aircraft relative to the air mass through which it is flying. The true airspeed is important information for accurate navigation of an aircraft. Tra ...

(TAS) to be higher than the

Indicated Airspeed Indicated airspeed (IAS) is the airspeed of an aircraft as measured by its pitot-static system and displayed by the airspeed indicator (ASI). This is the pilots' primary airspeed reference. This value is not corrected for installation error, ...

. This increase in TAS leads to a greater touchdown speed and greater kinetic energy. More kinetic energy has to be absorbed by the brakes which necessitates a longer runway.

Headwinds and tailwinds

The headwind reduces the landing distance for an aircraft. Landing into a headwind reduces the

ground speed Ground speed is the horizontal component of the velocity of an aircraft relative to the Earth’s surface, also referred to as "speed over the ground". It is vital for accurate navigation that the pilot has an estimate of the ground speed that wil ...

(GS) for the same indicated airspeed (IAS). This is beneficial to pilots as well as Air traffic controllers (ATC). An aircraft landing into a headwind will require less runway and will be able to vacate the runway sooner. Tailwind increases the ground speed of an aircraft for the same IAS and thus a longer runway distance will be required for an aircraft to land. Landing with an unknown or unexpected tailwind could lead to the aircraft overshooting the runway.

Runway surface

Runway conditions affect take off and landing performance of an aircraft. The runway may be made up of concrete, asphalt, gravel or grass. An important safety concern at airports is the contamination of the runways due to ice, snow, water, rubber deposits etc. The landing distance required by an aircraft is much more in case of low friction runways which do not facilitate effective braking to occur.

Aquaplaning Aquaplaning or hydroplaning by the tires of a road vehicle, aircraft or other wheeled vehicle occurs when a layer of water builds between the wheels of the vehicle and the road surface, leading to a loss of traction that prevents the vehicle ...

is a phenomenon in which directional control is lost because of the presence of film of water between the rubber tires and the runway surface. The construction of grooved surface runways and regular maintenance, especially rubber removal, both help reduce runway slipperiness and facilitate good ground handling and effective braking.

Runway slope

An up-slope runway will allow an aircraft to land in a shorter distance. A down-slope runway will require a greater landing distance. It will take longer for the aircraft to touch down from 50 ft above the runway threshold, as the runway is falling away beneath the aircraft. Braking while going downhill is not as effective as on a level or up-slope runway.

Flap settings

Wing flaps are hinged surfaces on the trailing edge of the wings of a fixed-wing aircraft. High flap settings help an aircraft to increase the aerodynamic drag and reduce the stalling speed so that the aircraft can fly at low speeds safely. Flaps also lower the nose of the aircraft and give the pilots a better view of the ground ahead while landing.

References

{{Reflist, refs= *{{cite book, last=Swatton, first=Peter J., title=Aircraft performance theory for pilots, year=2000, publisher=John Wiley and Sons, 2000, isbn=0-632-05569-3, pages=368 *{{cite book, author=Federal Aviation Administration, title=Pilot's Encyclopedia of Aeronautical Knowledge, year=2007, publisher=Skyhorse Publishing Inc., 2007, isbn=978-1-60239-034-8, pages=352

External links

* https://web.archive.org/web/20110906044938/http://igga.net/FAARecommendsGroovedRunways.pdf Flight phases Aircraft performance