Nicolaki is French, so that may be an argument you will lose
However, you are correct in saying that if something is broken you would say "en panne". I was reading an old Paris Match magazine from the Millennium, and the day before New Year's, France had a "tempête" that ravaged the countryside and killed some people. Anyways, in the magazine was an article titled "La France en Panne" so you are correct, however, when used in aviation, the word is "pan" which derives from "panne" as Nicolaki said.
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