Since I have flown in aicraft as a kid, there was a sound audible when the aircraft is on ground (before taking off or after landing) which is similar to the sound a DJ does when he scratches the disks.

Sorry for the wird example, but I do not know how to explain it better. It is like the scratching of a disk and the sound starts at a higher pitch and it ends at a lower pitch. I am really interested in finding out what it is and why it happens, since I have never been able to find out how it is produced.

  • $\begingroup$ Would that sound by any chance be the one in this video? $\endgroup$
    – Jan Hudec
    Commented Jan 7, 2015 at 12:59
  • $\begingroup$ And if not, could you try to find a video that has it? There are many aircraft videos on youtube, so it's likely some will have it. $\endgroup$
    – Jan Hudec
    Commented Jan 7, 2015 at 13:00
  • $\begingroup$ @JanHudec Thanks for the link to the other question, I have linked it below in my answer. Should we still mark this question as duplicate though? $\endgroup$ Commented Jan 7, 2015 at 13:06
  • $\begingroup$ That must be the PTU, which sounds like a DJ scratching or a barking dog $\endgroup$
    – DeltaLima
    Commented Jan 7, 2015 at 13:09
  • $\begingroup$ This video shows the PTU itself. $\endgroup$
    – CGCampbell
    Commented Jan 7, 2015 at 13:54

1 Answer 1


There is a variety of sounds an aircraft can produce, some even depending on the type of aircraft you are sitting in. Without any further data or reference, the most likely events that you can hear during pushback, taxi or vacating the runway are:

  • Cargo Doors being shut and locked
  • Flaps being extended to take-off position
  • Flaps being raised after landing

There are many more things that you can hear from the cabin, so without further information, it will be difficult to pin-point.

Another option, if it was predominantly on Airbus aircraft, is the Power Tranfer Unit, which is described to sound like a barking dog or like a drill.

See also this question and the answers:
What is this sound from Airbus aircraft before take off?

  • $\begingroup$ Yes indeed! I just found the sound in this video I found on the other post. youtube.com/watch?v=9aGsXmNjPRw It is the PTU, I needed to know. Thank you very much. @SentryRaven $\endgroup$ Commented Jan 7, 2015 at 19:19

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