Strange TCAS Behaviour
Sitting at FL350 the other night, company aircraft, same type (both B744s), was sitting directly beneath us at FL330. He was so accurately under us in fact the RAD ALT was showing 2060'-2080' continuously. I've seen the radio altimeter flash up when flying over aircraft in the past but this was permanently on, very impressive!
Anyway, the TCAS initially showed him as 2000ft below, which was true, but for periods of 5-10 mins the TCAS return disappeared. Talked to him on 123.45 and sure enough, we had disappeared from his display too. Just wondering if there is some sort of "black hole" which exists for aircraft remaining stationery relative to each other, directly on top or beneath of one another.
Cheers,
TL