Originally Posted by
BluSdUp
The transponder is suppressed on ground.
Most types are switched on/ off on nosewheel squat switch.
If you dont believe me watch the guy racing down the rwy on takeoff next time you are on short final!
You can see him but TCAS cant. And voila he lifts, and there he is.
Same on landing behind a fella: Now he is there, now he is gone, ie on the runway, no more mode A and C.
I agree with you BluSdUp. The fact remains at least in my company is that the TA/RA mode is selected when cleared to line up. We are not 100% Boeing but I can not come to another conclussion than it would be a left over from the "old" days. Looking at the system there is no reason why you can not taxi around in TA/RA mode. As we do on the A330 but not on the B744 for some reason.
So I can not come to another conclussion that this a left over from the first days of TCAS