On Mar 5, 8:44*am, John Smith wrote:
If you ever want to climb above 15,000 ft in an airspace where a
tansponder is mandatory (which I do regularly), then you are just plain
illegal with the TT21. This may be "fairly meaningless" for you, it's
not for me and should not be for any pilot.

Saying something is "illegal" is a fairly useless statement. A lot of
things are illegal, ranging from driving at 60 in a 55 zone and on up.

I think you need to explain:

- what is the likely safety implication of flying above 15000 with a
TT21?

I suspect the answer is "none whatsoever".


- what is the penalty for being caught doing so? What is the chance of
being caught?

I don't know the answer to the first part but I think I can guess the
second.