D Ramapriya wrote:
... Since every transponder-equipped aircraft today
has TCAS, there'd have to be two pairs of previously dead pilots + a
stroke of awful luck for a midair collision to occur. After the advent
of TCAS, midairs are only a possibility in and around airports where
transponders are to be turned off...
Ramapriya

Sadly, quite wrong. Transponders with Mode S can be helpful.
Then there's the [many, many] aircraft with Mode C only.

Brian W