In article , Roy Smith
wrote:

I asked:
Do TCAS RA's take terrain into account?

Newps wrote:
Yes, the airplane knows how high it is. It will not drive it self into
the ground.

Bob Noel wrote:
TCAS units do not contain terrain databases.

I'm having a hard time making these two responses jive :-)

I haven't had an opportunity to check my TCAS sources. But
I seem to remember the TCAS II unit having some interface
with the Radar Altimeter. Also, I'm pretty sure that a GPWS
(or TAWS) warning/alert/whateveritiscalled takes priority over
an RA.

Note that a radar altimeter isn't normally used above 2500' agl.

does that help?

--
Bob Noel