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I'm not even close to an aviation enthusiast, but after watching some videos I found I have a deep misunderstanding on how airplanes work.

airplane image showing engine producing thrust and pushing the plane forwards.

I've seen many cases where one of the engines fail and the plane has to fly on a single engine for a long time.

How doesn't the fact that the forces are now uneven drives the airplane to a side drift? (I'm sure this is all wrong, but I just don't understand how)

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up vote 15 down vote accepted

It does. Asymmetric thrust will in fact force the airplane into a turn unless the pilot counteracts this by using rudder and aileron to command an equal turn force in the other direction. Typically both opposing rudder, and banking away from the dead engine will be used to result in straight (although uncoordinated) flight.

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oh, so I was right? I watched a video about Air Transat 236, and it didn't explained that. thanks. – wingleader May 24 '14 at 21:28
Well, from 06:13 until 06:26, the plane was flying with one engine providing thrust. During those few minutes, the pilot would have had to do as Skip suggests. After 06:26, the second engine died due to fuel starvation and the airliner was then a glider. – CGCampbell May 25 '14 at 0:35
@wingleader: All aircraft that carry more than 12 passengers must be able to fly with one engine inoperative (tested during certification) and pilots train it at least twice a year in simulator. There is really no immediate danger in such incidents (unless it's uncontained failure with secondary damage, but even Quantas 32, which was rather serious uncontained failure, flew for another almost 2 hours and safely landed). – Jan Hudec May 25 '14 at 19:54
@RussellBorogove: In 2-engine aircraft, it is always emergency (there is no danger yet, but there is no redundancy any more) and land at nearest suitable airport. In 4-engine aircraft the flight may be continued if there is enough fuel and no risk of further damage (usually when the engine was shut down manually because of indications outside limits rather than quit itself). Then it's up to discussion with dispatch. – Jan Hudec May 25 '14 at 19:58
@JanHudec: just for posterity because I have this discussion all the time: per definition, an engine failure in a perf class A is an urgency (pan-pan) not an emergency (mayday). – Radu094 Mar 20 '15 at 21:08

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