"Steven P. McNicoll" wrote in message ink.net...

"Ron Natalie" wrote in message
. ..

Mine are integegral to the comm.


Not all of them are.


Nobody said it had to be universal. You asked "what bizarre failure causes
you to lose comm and transponder and still leaves you confident that your
other avionics (presumably navigational gear) active?" And the answer is
that most of us carry a GPS that is entirely independent of the aircraft
electrical system. I've been twice in two different aircraft that have had the electrical
systems go dead (and in the case of mine, we had several failures in a row).
One was even IFR. In one case I had a GPS (and no backup comm) in the
other case I had backup COMM (without NAV).