Originally Posted by
D-OCHO
Strobe lights on is a good practice but only when crossing the runway. Not "sometimes we are 200m/300m from the threshold/crossing point".
Putting your transponder on on the ground is of no use to traffic landing or taking of from the runway you are crossing. TCAS is not directional so it can show you on another airplanes TCAS receiver on the other side of the airport or even outside the airport. Some airports require you to put your Transponder only on to see you on their Ground radar but they do not ask you to put your TCAS on.
TCAS, or rather Mode S transponders do actually transmit automatically a "ground flag" which indicates that the airplane is on the ground, triggered by the ground/air logic. Targets with a set ground flag are not displayed on other active TCAS units, excepts if those are defective or do not conform to the relevant standards. Having TCAS on, while on the ground, does not have any negative effect on others or itself as the Mode S transponder transmits its information whether the TCAS (display) is on or not. When i was on a Boeing type it was actually SOP to keep the TCAS on at all times, just switch off the transponder once parked at the gate, but not before, as most airports nowadays use the transponders signal anyway for their ground information systems. Now on the Bus it is transponder on when cleared to push until parked back on the stand (exactly the same as on the Boeing), however TCAS only on when cleared to line up until vacating the runway after landing. Both SOPs worked fine and there was absolutely no issue with having the TCAS on while on the Boeing, neither with any airport nor with any other plane.
The only issue that sometimes comes up, if someone switches his transponder to ON instead of AUTO on the ground, in that case it will show up on TCAS displays, and ATCO screens that filter out ground traffic (approach/departure). That said, yes, switching TCAS on on the ground does not give any benefit to other traffic, however, it can give additional situational awareness to yourself.