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 ...

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...

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 According to the International Civil Aviation Organization (ICAO), a runway is a "defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft". Runways may be a man-made surface (often asphalt concrete, as ...

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 one of the basic factors 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 increases.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', p. 486. Aviation Supplies & Academics, 1997. This occurs when the ...

of the aircraft. Stall is a reduction in the

lift coefficient In fluid dynamics, the lift coefficient () is a dimensionless quantity that relates the lift generated by a lifting body to the fluid density around the body, the fluid velocity and an associated reference area. A lifting body is a foil or a com ...

generated by a wing as angle of attack increases. Therefore, the minimum approach speed increases as the aircraft's weight increases. The

kinetic energy In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its accele ...

() that has to be overcome 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

A decrease in

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

of air results in decrease in both aircraft and Engine performance. High elevation airports are characterized by

low pressure In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possible ...

and high ambient temperatures. 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. Tr ...

(TAS) will 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, inst ...

indicated by the

Airspeed indicator The airspeed indicator (ASI) or airspeed gauge is a flight instrument indicating the airspeed of an aircraft in kilometers per hour (km/h), knots (kn), miles per hour (MPH) and/or meters per second (m/s). The recommendation by ICAO is to use km/h, ...

to the pilot in air of low density. This increase in TAS leads to greater touchdown speed hence increases the landing roll. More energy has to be absorbed by the brakes thus demanding the need of a longer runway. An increased density altitude means a longer landing distance.

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 speed of an aircraft relative to the Earth’s surface. It is vital for accurate navigation that the pilot has an estimate of the ground speed that will be achieved during each leg of a flight. An aircraft diving ve ...

(GS) for the same

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. Tr ...

(TAS). This is beneficial to pilots as well as

Air traffic controllers Air traffic control specialists, abbreviated ATCS, are personnel responsible for the safe, orderly, and expeditious flow of air traffic in the global air traffic control system. Usually stationed in air traffic control centers and control ...

(ATC). An aircraft landing into a headwind will require less runway and will be able to vacate the runway sooner. If the headwind decreases near the ground, there is a decrease in the airspeed of the aircraft and it will tend to sink and possibly undershoot the aiming point. Tailwind increases the ground speed of an aircraft for the same TAS and thus a longer runway distance will be required for an aircraft to land. Landing in a tailwind situation could lead to the aircraft overshooting the runway and colliding with objects or terrain.

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 fr ...

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 aeroplane to touch down from 50 ft above the runway threshold, as the runway is falling away beneath the aeroplane. Braking while going downhill is not as effective as on a level or up-slope runway.

Flap settings

Wing flap A flap is a high-lift device used to reduce the stalling speed of an aircraft wing at a given weight. Flaps are usually mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used to reduce the take-off distance and the landing ...

s 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