TCAS Altitude Information

[ISaidRightTurns]

Okay, here's the scenario.

There is a guy in or around the ATL terminal airspace that has some real transponder problems. We have had other a/c report him somewhere below 5k ft, but his mode C shows ~30k. This is a real problem because conflict alert constantly goes off when airplanes really at his reported altitude come close to his target. Also, it sets the snitch machine off constantly. However, none of the other a/c at altitude show him on TCAS. Why would that be, obviously he doesn't have mode S so it would rely on the C info, correct?

 

[cvsfly]

The TCAS II unit we have will only display aircraft that are + or - 9800' from our current altitude. So in a terminal area, unless you are overflying at cruise altitude, most will not display a 30,000' mode C report.

 

[ISaidRightTurns]

Yeah sorry, thats what I meant by at altitude. Like if unknown a/c shows a mode c of 301 and I have someone at FL290, they don't see him on TCAS.