I don't know if anyone else has experienced this but going head to head with a C-5 (and I'm in a Warrior) and they didn't have me on TCAS. I did check my XPNDR, which was on Mode C and transmitting properly. Another time, when my Father was going into Malta, there was a Seneca (or equivalent) ahead of them on the approach, and they didn't have that seneca on TCAS either. Any ideas?
Cheers.