Yeah I've heard stories of some people doing crazy, dangerous, illegal things in small planes and just turning their transponders off.
I was a passenger in a C182 once where the transponder antenna fell off midflight. It was very educational how much trouble ATC had seeing us. Even after telling them exactly where we were, flying the heading they gave us to present the broadside of the a/c to the radar antenna, they basically said "there's something that might be you there, but I can't really tell."
A big jet at FL370 should show up on primary, but I can see it depending on a bunch of factors.
I was a passenger in a C182 once where the transponder antenna fell off midflight. It was very educational how much trouble ATC had seeing us. Even after telling them exactly where we were, flying the heading they gave us to present the broadside of the a/c to the radar antenna, they basically said "there's something that might be you there, but I can't really tell."
A big jet at FL370 should show up on primary, but I can see it depending on a bunch of factors.