"Capt. Doug" wrote in message ...
Ron Natalie wrote in message Can TCAS issue an RA with only a mode A
return from the other aircraft?

I believe so, but can't find anything in my library to substantiate this.
Either way, our Ops manual allows for deviations if a threat to safety is
perceived.

What does it tell you to do? Can it figure out altitude without mode C (I guess
it can do the samething that it does for azimuth).