In the US, will the tower likely think my aircraft has been hijacked if I taxi with the flaps down?


Why are flaps retracted when an aircraft is parked on ground?


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    $\begingroup$ Note that the second link is to a document dated 40 years ago, and the first link says "was" rather than "is". Lots & lots has changed since 1980, and quite frankly the idea that you've landed at your filed destination & need to covertly communicate that you've been hijacked so you can be met by... somebody... who assembles as you taxi to your assigned parking spot... is a little dubious. $\endgroup$ – Ralph J Feb 7 at 22:29
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    $\begingroup$ Cecelia Cichan might have something to say about making the flaps a last-minute checklist item... $\endgroup$ – Harper - Reinstate Monica Feb 8 at 18:13
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    $\begingroup$ From reading the document, it seems like flaps were not used to communicate a hijacking at all, but rather as a signaling device to tell ATC whether armed intervention is requested after the general situation has already been established (note that retracting flaps after landing is also listed as a signal!). $\endgroup$ – ManfP Feb 12 at 17:06

will the tower likely think my aircraft has been hijacked if I taxi with the flaps down?


For the twenty-some-odd years I owned my plane, I only taxied with the flaps down (for important operational reasons), even at towered airports, and not once had anyone think I was being hijacked.

Indeed, it would be quite disconcerting (to say the least) for ATC to treat any behavior or condition not officially designated for the purpose as a signal that the aircraft has been hijacked.

For many airplane types, there are of course good reason not to leave the flaps down while taxiing. But worrying that ATC will think you've been hijacked isn't one of them.

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    $\begingroup$ Also, if it was something that everyone knew as as unspoken secret code, then it would also stand to reason that this would be broadly distributed information, meaning hijackers would also be aware of this "un-secret secret", rendering it more or less useless. $\endgroup$ – J... Feb 8 at 14:03
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    $\begingroup$ @J...: reasonable point, but I'll also point out that there are signals to ATC to indicate a hijacking, and they are well-documented. A hijacker that did their homework would know that. Many security procedures work best when, as is often the case, the criminal does not do their homework. "Security through obscurity" isn't a great approach to rely on as the primary defense, but it does help in many real-world scenarios. $\endgroup$ – Peter Duniho Feb 9 at 1:15
  • $\begingroup$ Well, yes, but in this case it also suffers from being wildly non-specific in the sense that a weird flap deployment could just be a rookie mistake or even a reasonable flight configuration for some number of edge-case scenarios. $\endgroup$ – J... Feb 9 at 1:57
  • $\begingroup$ @J...: yes, definitely so. Hence the note to that effect in my post. :) $\endgroup$ – Peter Duniho Feb 9 at 1:59

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