Our Airbus A320 FCOM prescribes that the PM sets the PARK BRK ON before the walkaround.

Simple question: why?


1 Answer 1


There is something called a brake wear indicator on the bogie of the A320. To get an accurate reading from this, the parking brake needs to be on. It's not because if the brakes are off the plane will roll off, cause chocks are there.

  • 2
    $\begingroup$ In my experience, the break wear indicators - most of the time - are visible regardless of the position of the parking brake. Are they actually moving when the parking brake is applied? $\endgroup$
    – Ulu83
    Commented Jan 6 at 12:08
  • 7
    $\begingroup$ The indicator pins are probably still visible with the parking brake released, but to get an accurate reading, they should be checked with the brakes set. The calibration is that the pin is flush with the rest of the assembly with brakes set when the pads are at their wear limit. With brakes released, there is movement and the top of the pin would no longer be flush, so the reading would be inaccurate. $\endgroup$
    – Ralph J
    Commented Jan 6 at 16:01
  • 1
    $\begingroup$ And here I was envisioning the pilot, copilot and ground crew chasing the rolling A320 across the tarmac because Bob forgot to set the parking brake. Takes all the fun out of it! :) $\endgroup$
    – FreeMan
    Commented Feb 21 at 19:11

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