This is from CNN Can planes fly on one engine

"Basically, these planes are built to fly as well on one engine as they can on two."

The verb "fly on" has drawn my attention. Maybe it is because of my native language, I would expect it to say "fly with one engine" instead of "fly on one engine".

If I said "fly with" instead of "fly on", would it be wrong?

  • 'Fly with' suggests there may be just one engine fitted, or working, at take-off, not that it can still operate during a flight if one engine fails. And it's hyperbole - no plane can fly as well on one engine, because the thrust is biased to one side. The plane does have two engines, the other is not optional. Re motor vehicles the idiomatic expression is "It's only firing on three cylinders". Jul 31, 2023 at 22:05
  • Random side note, the title of the question in the side bar made me think of a housefly either sitting on an engine, or having an engine attached ..... clearly not the intent of your question once I saw the context. ;) Aug 1, 2023 at 19:32

3 Answers 3


Either is perfectly OK.

See various usage:





etc, etc.

The meaning is identical. Use either.

  • One is idiomatic, the other isn't, regardless of usage you found. Jul 31, 2023 at 22:12
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    Avoid linguistic prescriptivism. (Especially from a minority of one. Very lonely!).
    – BadZen
    Jul 31, 2023 at 22:14
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    @WeatherVane Which one do you think is un-idiomatic? I genuinely don't know. As a native Brit both sound perfectly idiomatic to me. I feel I would be marginally more likely to say "on" than "with" but there really isn't much in it; I could see myself saying "with" and I'd not notice if another native speaker said "with".
    – Muzer
    Aug 1, 2023 at 11:17
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    @Muzer I would say that "flying on one engine" is idiomatic. The other isn't wrong though. Similarly "we are running on diesel". Aug 1, 2023 at 11:20

"Fly with" is definitely not incorrect.

To my ear "fly with one engine" is slightly more formal than "fly on one engine", and if I were writing a scholarly essay, I'd opt for "fly with" - but that's just a feeling; I've never written and barely ever read scholarly papers on aviation.

Prepositions like with and on have many and varied uses, so it's rather difficult to guess which one will be idiomatic, and probably pointless to try to translate directly from one language to another.

In this case, with probably means either

6 a —used as a function word to indicate the means, cause, agent, or instrumentality

As in "the dolphin can swim up to 60 kilometres per hour with its powerful tail fin"


4 a —used as a function word to indicate combination, accompaniment, presence, or addition

As in "I went hiking with my new backpack"

While on might mean

2 b —used as a function word to indicate a source of dependence

As in "this car runs on electricity"

Or a definition that I can't find in a dictionary, but which we can see in examples like, "I bought fifteen bottles of wine at the chateau, but they were so good, I'm already on my last bottle."

  • How would you parse 'I'm on my third wife'? Jul 31, 2023 at 21:52
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    It's an idiom: "I am flying on one engine". And "He is on his third wife" isn't a physical description. Jul 31, 2023 at 22:11
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    I think 2b is actually a bit too broad here. This is a more detailed sense describing specifically the lack of sufficiency in a source of dependence: flying on one engine, marching on an empty stomach, a car running on empty (= with almost no fuel left in the tank), living on two bananas a day, etc. I haven’t found a dictionary that gives this as a separate sense, but I do think it’s different from the broader sense of just describing what something needs to function. Aug 1, 2023 at 8:54
  • @WeatherVane '"He is on his third wife" isn't a physical description.' -isn't it? Aug 1, 2023 at 13:08
  • @JanusBahsJacquet, I agree with that and your examples are of the same sort that I was going for with "on my last bottle". I'll see if I can incorporate this into my answer.
    – Juhasz
    Aug 1, 2023 at 16:53

It wouldn't be wrong, but it would IMO be slightly less clear.

There are two possible interpretations of "fly with one engine". One of these, presumably the intended one, is "fly using one engine". However, you could interpret it more literally as flying with only one engine present. Using "on" rather than "with" makes it clear that you are talking about whether you have power coming from the engine rather than whether you have the engine itself.

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