KLM Fokker 70 with reverse thrust applied. The two surfaces behind the engine can be seen in the deployed position, diverting the engine exhaust gases forward

Reverse thrust is the temporary diversion of a jet engine's output so that the exhaust gases are blown forwards rather than backwards. The resulting thrust force acts against the forward travel of the aircraft. Reverse thrust is used by many jet aircraft to help slow down just after touch-down, thus reducing wear on the brakes and enabling the aircraft to use shorter runways. It is also available on many propeller-driven aircraft through changing the pitch of the propeller blades to a negative angle, thereby directing air flow into the direction of travel. Image File history File links Download high resolution version (1000x706, 127 KB) Reverse thrust on a Fokker 70 of KLM at Bristol International Airport, Bristol, England. ... Image File history File links Download high resolution version (1000x706, 127 KB) Reverse thrust on a Fokker 70 of KLM at Bristol International Airport, Bristol, England. ... KLM (in full: Koninklijke Luchtvaart Maatschappij, literally Royal Aviation Company; usual English: Royal Dutch Airlines) is a subsidiary of Air France-KLM. Before its (agreed) take-over by Air France, KLM was the national airline of the Netherlands. ... Categories: Stub | Dutch airliners 1990-1999 ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... Jet aircraft with condensation trail Jet aircraft are aircraft with jet engines. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... A controllable pitch propeller (CPP) or variable pitch propeller is a special type of propeller with blades that can be rotated around their long axis to change their pitch. ...

Regulations dictate, however, that a plane must be able to land on a runway without the use of reverse thrust in order to be certified to land there.

The application of reverse thrust can be identified by a sudden increase in the volume and pitch of the engines' sound just after touch-down. The reversers are usually clearly visible at the rear of the engines during use.

Frequently landings will use "idle reverse thrust" in which the engines do not actually spool up, but the reversers are activated. This use of the reversers saves fuel, aids in noise abatement and improves engine life.

There are several different ways of reversing the thrust of a turbofan. The illustration shows a Target Reverser, where all of the efflux is reversed. Some high bypass ratio engines, use blocker doors in the bypass duct to redirect (just) the bypass air through a Cascade Reverser. CFM56-3 turbofan, lower half, side view. ... Typical bypass duct, in a high bypass ratio turbofan A bypass duct is an annular passage that allows some of a turbofans airflow to bypass the engine core, or gas generator. ...

On most modern modern jet aircraft, thrust reversers are not intended under any circumstances for use in-flight and have directly contributed to the crashing of at least one airliner, specifically Lauda Air Flight NG004. The Boeing 767-300 aircraft suffered a premature deployment of the No.1 thrust reverser, which caused the airliner to stall, and crash.[1] Lauda Air Flight 004 was an international scheduled passenger flight flown by Lauda Air, the Austrian airline founded by retired Formula 1 race driver Niki Lauda. ... Air Canada Boeing 767-300 British Airways Boeing 767-300 The Boeing 767 is a commercial passenger airplane manufactured by Boeing Commercial Airplanes. ...

However some aircraft are able to safely use reverse thrust in flight, though the majority of these are propellor driven (For example, the ATR 72 is able to use reverse thrust in flight should the appropriate control lock be withdrawn. The Hawker Siddeley HS121 Trident (120-180 seat airliner) was capable of descending at up to 10,000ft/min by the in-flight of the thrust reversers, though this capability was rarely used and none of the typeare currently airworthy.

External links

• Reducing Landing Distance