Thanks for the heads up on TCAS found this description
TCAS: Preventing Mid-Air Collisions - AeroSavvy
and how Santa's sleigh is TCAS equipped, with the speed he moves I think he needs PAW, SE2, Flarm
and of course for see and be seen he has Rudolph's red nose.
I see that no GPS is used and only works by giving level changes but no heading changes.
Directional aerial and signal power seem to give location of threat when the TCAS triggers other Transponders
then they talk to each other to decide on actions or if one party has no TCAS what to do.
Seems no outside support needed. PAW does range the same way for mode C & S.