Landing

Landing is the last part of a flight where a flying animal or aircraft returns to the ground. Hitting the ground too hard is prevented by wings (including rotor wings), a parachute or rockets or a vertically directed jet engine; in the case of a balloon the buoyancy is slightly decreased for a soft landing.

For aircraft or birds, landing is generally accomplished by trading airspeed for lift. The first phase is the flare when the rate of descent will be reduced by effectively stalling the plane, with a rotation in pitch into the landing attitude shortly before reaching the ground. The nose continues to rise which increases the angle of attack of the wings and therefore the amount of lift generated, as the airspeed gradually reduces.

In a perfect touchdown, assuming there is no crosswind, contact with the ground is made just as the forward speed is reduced to the point where there is no longer sufficient lift to remain aloft. If there is a crosswind, techniques such as a crab landing or a slip landing are used to land the plane safely.

During landing, the ground effect becomes significant for aircraft. This tends to make the aircraft "keep flying" when it ordinarly would not (at higher altitudes) and therefore to extend the distance required to land.

Large jet transport aircraft land a bit differently to that described above. If you waited for the aircraft to stall you would use up too much runway. In large jet aircraft the flare just reduces the rate of descent at touchdown and the aircraft is flown onto the runway.