Skywise wrote:

I'm sorry, but how can a frequency be "unavailable in that patch
of airspace"?!?! If the transmitter and the receiver can tune to
the frequency, it's available unless it's already in use or being
jammed.

It was being jammed by an ELT.

George Patterson
"Naked" means you ain't got no clothes on; "nekkid" means you ain't got
no clothes on - and are up to somethin'.