Does the flight data recorder record whether the cockpit door lock was deliberately used to lock someone out?

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    $\begingroup$ How could one detect the reason why the door was locked? The best you could do is record the fact that it was locked. $\endgroup$
    – terdon
    Mar 27, 2015 at 13:23
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    $\begingroup$ @terdon it is possible to override the door lock from the inside even if the correct keycode is entered on the outside. $\endgroup$
    – Erich
    Mar 27, 2015 at 13:25
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    $\begingroup$ @terdon the edits changed the original question somewhat $\endgroup$
    – orique
    Mar 27, 2015 at 13:27
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    $\begingroup$ @Simon Your edit unnecessarily removed significant parts of the question. This is not accident speculation; it does not put forward or ask for an opinion on any particular theory. Without the specification of A320 in Europe, this question is a lot more general. We do allow accident-specific questions on here. $\endgroup$ Mar 27, 2015 at 16:33

2 Answers 2


While it is not on the required parameters list, it would not surprise me if it would be recorded- most FDRs record considerably more than the 88 mandatory parameters, and cockpit doors are of course interesting in accident investigations.

That being said, it should also come across pretty evidently on the Cockpit Voice Recorder if somebody was trying to get in. The normal request is a pretty distinct buzzer and the emergency request is the same buzzer for 5 minutes unless denied/ cancelled by the pilot. The door also locks quite loudly. Both should be able to be picked up by the general cockpit area microphone (CAM).

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    $\begingroup$ Good point about the sounds. $\endgroup$
    – orique
    Mar 27, 2015 at 11:29

ICAO Annex 6 part 1 (Appendix 8) lists parameters required to be recorded on digital flight data recorders. This should give you a general sense of what gets recorded, but cockpit door locking state is not among them.

The caveat to this is many of these might not be individually codified in regulation by member parties to the convention. Carriers are regulated by their state of registration. In the United States, cockpit door locking state is not one of the required parameters mandated by the FAA.

(The original answer specifically mentioned European regulations, but has since changed to a general question. My answer has been edited accordingly.)

  • $\begingroup$ And as most of those locks are simple mechanical latches, there being no electrical circuits involved, no sensors and wiring leading to the door, it'd be pretty hard to detect and record, and a major investment would be required to install such a system and get it certified. $\endgroup$
    – jwenting
    Mar 27, 2015 at 8:43
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    $\begingroup$ @jwenting at least in an A320 seems like the lock is actuated with an electrical switch. $\endgroup$
    – orique
    Mar 27, 2015 at 9:27
  • $\begingroup$ I don't see why you specified European or A320. Neither were in the question. $\endgroup$ Mar 27, 2015 at 12:26
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    $\begingroup$ @raptortech97 The question contained both European and A320 until it was edited by other people to remove that. And I don't see why somebody shouldn't mention Europe in their answer. Not everyone lives in the USA, you know. $\endgroup$ Mar 27, 2015 at 16:26
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    $\begingroup$ @DavidRicherby Thanks, I didn't see that. And I'm not suggesting that everyone should always talk about the US, but the answer specifically gave the answer for the FAA with the disclaimer "Not that this would translate precisely to European carriers," which was kinda out-of-the blue. $\endgroup$ Mar 27, 2015 at 16:28

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