Transponder code question.
If an aircraft squawking an ATC assigned code suffers, for example, a decompression and makes a Mayday call before commencing a rapid descent I find that many airlines' policy appears to be to routinely change the squawk to 7700.
I clearly remember from years ago that this was not the preferred procedure unless specifically requested to do so by ATC.
Has that policy changed or is my memory wrong?
What is the current ATC expectation and if possible can someone supply a definitive reference?
I am generally considering European airspace but would be interested in policy elsewhere in the world.
Last edited by M.Mouse; 5th Dec 2016 at 22:07.