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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 drive the airplane to a side drift? (I'm sure this is all wrong, but I just don't understand how)

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    $\begingroup$ Note that the engine force arrows should be pointing the other way. $\endgroup$
    – user14897
    Jun 19, 2018 at 10:58
  • $\begingroup$ @ymb1: Unless that plane's had a double engine failure, in which case the arrows are the right way around for the force generated by those giant windmilling drag buckets. $\endgroup$
    – Vikki
    May 29, 2019 at 1:07
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    $\begingroup$ @Sean: Indeed 🤣 $\endgroup$
    – user14897
    May 29, 2019 at 1:08

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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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    $\begingroup$ Passengers would very likely notice. There'd be a change in sound, and the pilot would have to "feel around" for the right balance of controls to compensate for the asymmetrical thrust. And, yes, I'd expect a divert to the nearest suitable airfield if the plane wasn't very close to its original destination. $\endgroup$
    – Russell Borogove
    May 25, 2014 at 15:33
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    $\begingroup$ @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). $\endgroup$
    – Jan Hudec
    May 25, 2014 at 19:54
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    $\begingroup$ @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. $\endgroup$
    – Jan Hudec
    May 25, 2014 at 19:58
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    $\begingroup$ @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). $\endgroup$
    – Radu094
    Mar 20, 2015 at 21:08
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    $\begingroup$ @Radu094: Mayday implies there is an imminent danger to the flight. It does not necessarily mean it's not capable of sustained flight at all. $\endgroup$
    – Jan Hudec
    Mar 23, 2015 at 7:08

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