Landing
Landingis the last part of aflight,where a flyinganimal,aircraft,orspacecraftreturns to the ground. When the flying object returns to water, the process is calledalighting,although it is commonly called "landing", "touchdown"aor "splashdown"as well. A normal aircraft flight would include several parts of flight includingtaxi,takeoff,climb,cruise,descentand landing.
Aircraft[edit]
Aircraft usually land at anairporton a firmrunwayorhelicopter landing pad,generally constructed ofasphalt concrete,concrete,gravel or grass. Aircraft equipped with pontoons (floatplane) or with a boat hull-shaped fuselage (aflying 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 gearorspeed brakes.When a fixed-wing aircraft approaches the ground, the pilot will move the control column back to execute aflareor round-out. This increases theangle 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 atricycle gearaircraft or on all three wheels simultaneously in the case of aconventional landing gear-equipped aircraft, commonly referred to as a "taildragger".[1][2][3][4]
Light aircraft[edit]
In alight 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 littlecrosswind,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. Thestallwarning 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:
- Normal landings[4]
- Crosswind landings- where a significant wind not aligned with the landing area is a factor[4]
- Short field landings - where the length of the landing area is a limiting factor[4]
- Soft and unprepared field landings - where the landing area is wet, soft or has ground obstacles such as furrows or ruts to contend with[4]
Large aircraft[edit]
In largetransport 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. Aflareis 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 mechanicalbraking,such as anautobrakesystem, can take effect.Reverse thrustis used by manyjet aircraftto help slow down just after touch-down, redirecting engine exhaust forward instead of back. Somepropeller-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'.
Environmental factors[edit]
Factors such ascrosswindwhere the pilot will use acrab landingor aslip landingwill 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,avionicsand the overall situation.
For example, landing a multi-engineturbopropmilitary such as aC-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 aCessna 150on a paved runway in uncontrolled airspace, which is different from landing an airliner such as anAirbus A380at a major airport withair 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]
Parachutes[edit]
The term "landing" is also applied to people or objects descending to the ground using aparachute.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 adandelion.
On the other hand, modernram-air parachutesare essentially inflatable wings that operate in agliding flightmode. Parachutists execute a flare at landing, reducing or eliminating both downward and forward speed at touchdown, in order to avoid injury.[11]
Spacecraft[edit]
Sometimes, a safe landing is accomplished by using multiple forms of lift, thrust (propulsive landing[12]) and dampening systems. Both theSurveyoruncrewed lunar probe craft and theApollo Lunar Moduleused a rocket deceleration system and landing gear to soft-land on the moon. Several Soviet rockets including theSoyuz spacecrafthave used parachutes andairbag landing systemsto dampen the landing on earth. In November 2015,Blue Origin'sNew Shepardbecame the first rocket to cross theKármán line(edge of space at 100 km altitude) and land vertically back on Earth. In December 2015,SpaceX'sFalcon 9became the first launch vehicle on an orbital trajectoryto successfully vertically-land and recoverits first stage, although the landed first stage was on a sub-orbital trajectory.
See also[edit]
- Arresting gear
- Hard landing
- Landing performance
- Visual approach
- Instrument approach
- Instrument landing system(ILS)
- Instrument flight rules(IFR)
- Visual flight rules(VFR)
Notes[edit]
References[edit]
- ^Aviation Glossary (2011)."Flare (ICAO Definition)".Retrieved26 January2011.
- ^International Civil Aviation Organization(June 2010)."Phase of Flight Definitions and Usage Notes"(PDF).Retrieved26 January2011.
- ^Crane, Dale:Dictionary of Aeronautical Terms, third edition,page 217. Aviation Supplies & Academics, 1997.ISBN1-56027-287-2
- ^abcdefTransport Canada:Aeroplane Flight Training Manual, 4th Edition,pages 104-115. Gage Educational Publishing Company, 1994.ISBN0-7715-5115-0
- ^Aircraft.Volume 64. Royal Aeronautical Society Australian Division. 1984. p. 50.Retrieved28 February2023.
- ^Bjork, Lewis (1996).Piloting for Maximum Performance.McGraw-Hill. p. 229.ISBN978-0-07-005699-2.
- ^Jeffrey A., Roy (May–June 1990)."The Stabilized Approach".FAA Aviation News: A DOT/FAA Flight Standards Safety Publication.Flight Standards' Accident Prevention Program Branch, Federal Aviation Administration, Department of Transportation: 4.Retrieved28 February2023.
- ^NASA Technical Paper.National Aeronautics and Space Administration, Scientific and Technical Information Office. 1981. p. 6.Retrieved28 February2023.
- ^Aircraft Accident Report, United Airlines Flight 232, 19 July 1989.Appendix D: National Transportation Safety Board. p. 123.
- ^"Required Navigation Performance | GE Aviation Systems".GE Aviation. Archived fromthe originalon 29 July 2012.Retrieved16 July2012.
- ^United States Parachute Association(2008)."Canopy piloting skills".Archived fromthe originalon 15 October 2015.Retrieved6 September2011.
- ^Samad Hayati, et al,Strategic Technology Development for Future Mars Missions (2013-2022)Archived2013-02-21 at theWayback Machine,NASA, September 15, 2009
- ^"First Words of Safe Landing on Mars - Tango Delta Nominal".NASA. 21 August 2012.
External links[edit]
