Then there is the anticollision light system (blinking tail light or
strobes).


Bob Moore wrote in
. 122:

"Ramapriya" wrote

Does this get activated only when there's an aircraft in the dangerous
vicinity or will it also trigger if the aircraft is hurtling towards
some terrain such as a hill?

In my generation of aircraft, (B-727) they are two different systems.
First came the GPWS (Ground Proximity Warning System) and then some
time later came the TCAS (Traffic Alert and Collision Advoidance System).

And does every aircraft have this system these days, regardless of
size?

No, only passenger jets are required to have them.

Bob Moore