The performance data for landing

Landing

thumb|A [[Mute Swan]] alighting. Note the ruffled feathers on top of the wings indicate that the swan is flying at the [[Stall |stall]]ing speed...

 an aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft 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.Although...

 can be obtained from the aircraft's flight manual or pilot's operating Handbook. The actual landing performance of an aircraft is affected by many variables which must be taken into account.

Weight

The weight of an aircraft is one of the basic factors that determines the length of the landing roll of an aircraft. An increase in weight increases the stall speed of an aircraft. Stall

Stall

In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded...

 is a reduction in the lift coefficient generated by a wing as angle of attack increases. Therefore, the minimum approach speed is much higher in case of heavier aircraft's. The kinetic energy

Kinetic energy

The kinetic energy of an object is the energy which 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 acceleration, the body maintains this kinetic energy unless its speed changes...

 (1/2 mV^2) that has to be overcome to stop an airplane, is a function of the mass of the airplane and the square of the speed at touchdown. The kinetic energy in case of heavier aircraft's is higher and the brakes have to absorb this greater energy, increasing the landing run of an aircraft.

Density Altitude

A decrease in density

Density

The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...

 of air results in decrease in both aircraft and Engine performance. High elevation airports are characterized by low pressure and high ambient temperatures. The True Airspeed

True airspeed

True airspeed of an aircraft is the speed of the aircraft relative to the airmass in which it is flying. True airspeed is important information for accurate navigation of an aircraft.-Performance:...

 (TAS) will be higher than the Indicated airspeed

Indicated airspeed

Indicated airspeed is the airspeed read directly from the airspeed indicator on an aircraft, driven by the pitot-static system. IAS is directly related to calibrated airspeed , which is the IAS corrected for instrument and installation errors....

 indicated by the Airspeed indicator

Airspeed indicator

The airspeed indicator or airspeed gauge is an instrument used in an aircraft to display the craft's airspeed, typically in knots, to the pilot.- Use :...

 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(GS) for the same TAS. This is beneficial to both, the pilots as well as the Air traffic controllers (ATC). An aircraft landing into a headwind will require lesser runway and will be able to vacate the runway sooner. If the headwind decreases near the ground, there's a decrease in the performance of the aircraft and it will tend to sink and possibly under shoot 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 a stall because of the tendency of the pilot to reduce the airspeed while landing. Also, there's a chance of over shooting the runway and colliding with objects or terrain.

Runway Surface

Runway conditions affect take off and landing performance of an aircraft. The runway can be made up of Concrete, asphalt, gravel or grass. An important safety concern at the 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 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. One solution to this is the construction of grooved surface runways which are aimed at eliminating runway slipperiness and facilitate good ground handling and impressive 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 and of course braking while going downhill is not as effective as on a level or up slope runway.

Flap Settings

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 enable pilots to take a steeper approach path while landing.