Phil W Lee <phil(at)lee-family(dot)me(dot)uk> wrote
>So the ground station may initiate an abbreviation, but if the air
>station continues to use the full callsign, the ground station should
>revert.
I think few ATCOs, particularly outside the UK, know about the rule
that only the ground station may initiate the abbreviation.
As regards duplicate callsigns, I always tell ATC "there are two N-XX
on frequency". They always appreciate it.
The standard of ATC RT in some European countries is atrocious,
without getting into details like this. Italy comes to mind
immediately, but there is a whole bunch.
"fox" or "foxtrot"? 
