Landing
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Mytravel Airbus A320 landing |
Landing is the last part of a
flight, where a flying animal or
aircraft returns to the ground. When the flying object returns to water, the process is called
alighting, although it is commonly called "landing" as well. 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. Aircraft usually land at an
airport on a
runway or
helicopter landing pad.
For aircraft or birds, landing is generally accomplished by gradually tapering down airspeed and lift. The first phase is the
flare, where the rate of descent will be reduced by transitioning to a
stall attitude. After slowing down, the plane changes
pitch into the
landing attitude shortly before touching down.
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 ordinarily would not (at higher altitudes) and therefore to extend the distance required to land.
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A Mute Swan alighting. Note the ruffled feathers on top of the wings indicate that the swan is flying at the stalling speed. The extended and splayed feathers act as lift augmenters in the same way as an aircraft's slats and flaps. |
Large
transport category (airliner) aircraft land differently than described above. If the pilot waited for the aircraft to stall too much runway length would be used so the flare just reduces the rate of descent at touchdown and the aircraft is flown onto the runway. Usually
spoilers (Sometimes called "Lift Dumpers") are immediately deployed to dramatically reduce the lift and transfer the aircraft's weight to its wheels, where mechanical
braking can take effect.
Reverse thrust is used by many
jet aircraft to help slow down just after touch-down.
To land on an
aircraft carrier, a conventional aircraft (moving at, perhaps, 150 mph (240 km/h)) is equipped with tailhooks to engage one of up to four
arresting cables stretched across the deck, stopping the aircraft within 320 feet (100 m) after engaging one of the cables. To assist safe landings, the carrier will usually steam directly into wind at full speed, thus reducing aircraft's speed relative to the carrier deck, and eliminating any crosswind.
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Cruise*
Takeoff*
Water Landing*
Emergency Landing
