On Apr 4, 4:47*pm, Papa3 wrote:
Hi,

Quick google search on "TCAS filter slow" and similar didn't get me
what I wanted, so here goes... *Do TCAS systems filter out targets
which have slow/no ground speed?

Reason for asking... *I got into wave yesterday, and while climbing
through 11,000 MSL NW of Allentown PA had an American Airlines CRJ
pass nearby. * I would guesstimate that he was about 500 above and a
half mile horizontal. * It wasn't really close - I had him in sight
for over a minute and was edging away laterally to gain separation.
But, it was a little closer than the published TA/RA numbers I've seen
in manuals. * * I was essentially stationary for 20 minutes.

By comparison, later in the flight I watch an A300 make a sweeping
turn around me at 9,000 as I crossed a well-published STAR. * I also
checked in with Allentown approach, and they painted me just fine on
their ground radar.

Curious...

P3

Approach painted you well? As in they could see your transponder
return?
TCAS needs you to have a transponder for it to work.
If approach could only see your skin paint raw radar return, TCAS
would not work, and if you had near zero GS in wave, then the approach
radar would have filtered you out during that time frame.

T