"BUFDRVR" wrote
Mailman wrote:

...which proves, yet again, how little journalists understand: setting the
transponder/IFF to emergency mode is done in a hijacking - or any other
emergency.

Uhhh...no. The ICAO transponder emergency distress code is 7700 while hijacking
is (I think??) 7200. There's also one for NORDO (No Radio) which I think is
7600.

7500 for hijack. Your other guesses are correct. 77 and 76 came from the old
64 code days. Back when there was only 10 airplanes within a hundred miles of
an airport :-) 00 was the intercept code, and 11 was the interceptor weapons free
code (nuclear). 12 was contact flying below 12kft.