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" a or "splashdown" as well. A normal aircraft flight would include several parts of flight including taxi, takeoff, climb, cruise, descent and landing.
Aircraft usually land at an airport on a firm runway or helicopter landing pad, generally constructed of asphalt concrete, concrete, gravel or grass. Aircraft equipped with pontoons (floatplane) or with a boat hull-shaped fuselage (a flying boat) are able to land on water. Aircraft also sometimes use skis to land on snow or ice.
To land, the airspeed and the rate of descent are reduced such that the object descends at a low enough rate to allow for a gentle touch down. Landing is accomplished by slowing down and descending to the runway. This speed reduction is accomplished by reducing thrust and/or inducing a greater amount of drag using flaps, landing gear or speed brakes. When a fixed-wing aircraft approaches the ground, the pilot will move the control column back to execute a flare or round-out. This increases the angle of attack. Progressive movement of the control column back will allow the aircraft to settle onto the runway at minimum speed, landing on its main wheels first in the case of a tricycle gear aircraft or on all three wheels simultaneously in the case of a conventional landing gear-equipped aircraft, commonly referred to as a "taildragger". [1] [2] [3] [4]
In a light aircraft, power is adjusted to control the descent rate, and pitch attitude is adjusted to control airspeed, [5] although theoretically they must be adjusted together. [6]
In a light aircraft, with little crosswind, the ideal landing is when contact with the ground occurs as the forward speed is reduced to the point where there is no longer sufficient airspeed to remain aloft. The stall warning is often heard just before landing, indicating that this speed and altitude have been reached. The result is very light touch down. [4]
Light aircraft landing situations, and the pilot skills required, can be divided into four types:
In large transport category (airliner) aircraft, pilots land the aircraft by "flying the airplane on to the runway."[ citation needed ] The airspeed and attitude (pitch angle) of the plane are adjusted for landing. Thrust and pitch must be adjusted together, [7] however the technique is reversed compared to light aircraft. [8] In large aircraft, thrust is used to control airspeed and pitch is used to control rate of descent. [9] The airspeed is kept well above stall speed and at a constant rate of descent. A flare is performed just before landing, and the descent rate is significantly reduced, causing a light touch down. Upon touchdown, spoilers (sometimes called "lift dumpers") are deployed to dramatically reduce the lift and transfer the aircraft's weight to its wheels, where mechanical braking, such as an autobrake system, can take effect. Reverse thrust is used by many jet aircraft to help slow down just after touch-down, redirecting engine exhaust forward instead of back. Some propeller-driven airplanes also have this feature, where the blades of the propeller are re-angled to push air forward instead of back using the 'beta range'.
Factors such as crosswind where the pilot will use a crab landing or a slip landing will cause pilots to land slightly faster and sometimes with different aircraft attitude to ensure a safe landing.
Other factors affecting a particular landing might include: the plane size, wind, weight, runway length, obstacles, ground effects, weather, runway altitude, air temperature, air pressure, air traffic control, visibility, avionics and the overall situation.
For example, landing a multi-engine turboprop military such as a C-130 Hercules, under fire in a grass field in a war zone, requires different skills and precautions than landing a single engine plane such as a Cessna 150 on a paved runway in uncontrolled airspace, which is different from landing an airliner such as an Airbus A380 at a major airport with air traffic control.
Required Navigation Performance (RNP) is being used more and more. Rather than using radio beacons, the airplane uses GPS-navigation for landing using this technique. This translates into a much more fluid ascent, which results in decreased noise, and decreased fuel consumption. [10]
The term "landing" is also applied to people or objects descending to the ground using a parachute. Some consider these objects to be in a controlled descent instead of actually flying. Most parachutes work by capturing air, inducing enough drag that the falling object hits the ground at a relatively slow speed. There are many examples of parachutes in nature, including the seeds of a dandelion.
On the other hand, modern ram-air parachutes are essentially inflatable wings that operate in a gliding flight mode. Parachutists execute a flare at landing, reducing or eliminating both downward and forward speed at touchdown, in order to avoid injury. [11]
Sometimes, a safe landing is accomplished by using multiple forms of lift, thrust (propulsive landing [12] ) and dampening systems. Both the Surveyor uncrewed lunar probe craft and the Apollo Lunar Module used a rocket deceleration system and landing gear to soft-land on the moon. Several Soviet rockets including the Soyuz spacecraft have used parachutes and airbag landing systems to dampen the landing on earth. In November 2015, Blue Origin's New Shepard became the first rocket to cross the Kármán line (edge of space at 100 km altitude) and land vertically back on Earth. In December 2015, SpaceX's Falcon 9 became the first launch vehicle on an orbital trajectory to successfully vertically-land and recover its first stage, although the landed first stage was on a sub-orbital trajectory.
Takeoff is the phase of flight in which an aerospace vehicle leaves the ground and becomes airborne. For aircraft traveling vertically, this is known as liftoff.
An airfield traffic pattern is a standard path followed by aircraft when taking off or landing while maintaining visual contact with the airfield.
In aviation, a go-around is an aborted landing of an aircraft that is on final approach or has already touched down. A go-around can either be initiated by the pilot flying or requested by air traffic control for various reasons, such as an unstabilized approach or an obstruction on the runway.
Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Articles related to aviation include:
Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engine's thrust for it to act against the forward travel of the aircraft, providing deceleration. Thrust reverser systems are featured on many jet aircraft to help slow down just after touch-down, reducing wear on the brakes and enabling shorter landing distances. Such devices affect the aircraft significantly and are considered important for safe operations by airlines. There have been accidents involving thrust reversal systems, including fatal ones.
A slip is an aerodynamic state where an aircraft is moving somewhat sideways as well as forward relative to the oncoming airflow or relative wind. In other words, for a conventional aircraft, the nose will be pointing in the opposite direction to the bank of the wing(s). The aircraft is not in coordinated flight and therefore is flying inefficiently.
In aviation, autoland describes a system that fully automates the landing procedure of an aircraft's flight, with the flight crew supervising the process. Such systems enable airliners to land in weather conditions that would otherwise be dangerous or impossible to operate in.
The Shuttle Training Aircraft (STA) is a former NASA training vehicle that duplicated the Space Shuttle's approach profile and handling qualities, allowing pilots to simulate Shuttle landings under controlled conditions before attempting the task on board the orbiter. The STA was also flown to assess weather conditions just prior to Space Shuttle launches and landings.
The Learjet 25 is an American ten-seat, twin-engine, high-speed business jet aircraft manufactured by Learjet. It is a stretched version of the Learjet 24.
On 22 November 2003, shortly after takeoff from Baghdad, Iraq, an Airbus A300B2-200F cargo plane, registered OO-DLL and owned by the Belgian division of European Air Transport, was struck on the left wing by a surface-to-air missile while on a scheduled flight to Muharraq, Bahrain. Severe wing damage resulted in a fire and complete loss of hydraulic flight control systems. Because outboard left wing fuel tank 1A was full at takeoff, no fuel-air vapour explosion occurred. Liquid jet fuel dropped away as 1A disintegrated. Inboard fuel tank 1 was pierced and leaking.
DuPage Airport is a general aviation airport located 29 miles (47 km) west of downtown Chicago in West Chicago, DuPage County, Illinois, United States. It is owned and operated by the DuPage Airport Authority, which is an independent government body established by law by the state of Illinois. It also serves as a relief airport for O'Hare International Airport and Chicago Midway International Airport, both in nearby Chicago.
In aviation, a crosswind landing is a landing maneuver in which a significant component of the prevailing wind is perpendicular to the runway center line.
P‑factor, also known as asymmetric blade effect and asymmetric disc effect, is an aerodynamic phenomenon experienced by a moving propeller, wherein the propeller's center of thrust moves off-center when the aircraft is at a high angle of attack. This shift in the location of the center of thrust will exert a yawing moment on the aircraft, causing it to yaw slightly to one side. A rudder input is required to counteract the yawing tendency.
Lufthansa Flight 2904 was an Airbus A320-200 flying from Frankfurt, Germany to Warsaw, Poland that overran the runway at Okęcie International Airport on 14 September 1993.
Britannia Airways Flight 226A was an international passenger flight from Cardiff, Wales to Girona, Spain, operated by charter airliner Britannia Airways. On 14 September 1999, the Boeing 757-204 aircraft suffered a crash landing and broke apart during a thunderstorm in Girona-Costa Brava Airport. Of the 236 passengers and nine crew on board, two were seriously injured and 41 sustained minor injuries. One of the passengers who had apparently sustained only minor injuries died five days later of unsuspected internal injuries. The aircraft involved in the crash, Boeing 757-204 registration G-BYAG, was damaged beyond economical repair and scrapped.
Autorotation is a state of flight in which the main rotor system of a helicopter or other rotary-wing aircraft turns by the action of air moving up through the rotor, as with an autogyro, rather than engine power driving the rotor. The term autorotation dates to a period of early helicopter development between 1915 and 1920, and refers to the rotors turning without the engine. It is analogous to the gliding flight of a fixed-wing aircraft. Some trees have seeds that have wing-like structures that enable the seed to spin to the ground in autorotation, which helps the seeds to disseminate over a wider area.
FedEx Express Flight 14 was a scheduled cargo flight from Singapore to Newark, New Jersey, via Malaysia, Taiwan, and Alaska. On July 31, 1997, the aircraft flying this route crashed during landing on its final segment at Newark International Airport (EWR), inverting and catching fire, injuring all five people on board.
China Airlines Flight 605 was a daily non-stop flight departing from Taipei, Taiwan at 6:30 a.m. and arriving in Hong Kong at 7:00 a.m. local time. On 4 November 1993, the aircraft went off the runway and overran attempting to land during a storm. It was the first hull loss of a Boeing 747-400.
FedEx Express Flight 80 was a scheduled cargo flight from Guangzhou Baiyun International Airport in China, to Narita International Airport in Narita, Chiba Prefecture, Japan. On March 23, 2009, the McDonnell Douglas MD-11F (N526FE) operating the flight crashed at 6:48 am JST, while attempting a landing on Runway 34L in gusty wind conditions. The aircraft became destabilized at flare and touchdown resulting in an unrecovered "bounced" landing with structural failure of the landing gear and airframe following pilot error due to poor training for bounced landings. The plane came to rest off the runway, inverted, and burning fiercely. The captain and first officer, the jet's only occupants, were both killed.
The landing flare, also referred to as the round out, is a maneuver or stage during the landing of an aircraft.
