Originally Posted by
jondc9
I recall when TCAS first came out I asked: what if you get a TCAS RA that says climb and you are already at your max altitude?
a good answer was never forthcoming
Try this
ACAS II Bulletin which seems to answer your question. Refer to events 5 & 6 (pg. 3). The conclusion is...
"DO NOT react contrary to an RA [but] if there is some doubt of the ability to respond to a “Climb” RA, at least remain level, do not descend."
I'm sure we can all think of scenarios where this is not the ideal answer, but it seems the 'least bad' choice, all else being equal. Hope this is of some help.