[USNBandit]

You are correct that TCAS works independently of radar and ATC. TCAS equipped aircraft interrogate all Mode C and Mode S type transponders within a specified radius of their aircraft. The most basic version gives Traffic Advisories where subsequent models give Resolution Advisories.

I would imagine these aircraft would both have been equipped with latter variants of TCAS that would "command" the pilots of the aircraft to deviate in altitude to avoid the collision.

Factors that would complicate the problem would be if one or both aircraft were changing altitude, which challenges the system to figure out the altitude trend to compute the possible conflict. Another issue would be if a target aircraft was showing the wrong altitude from its Mode C.

[Western Phil]

Thanks for the information.