Had a few close shaves over the years but the closest was flying a B-747 (F) Singapore to London at F.L 310. Just west of Bombay requested and received clearance to climb F.L.350. As we climbed through 330, in cloud IMC and at night, heard opposite traffic taking a TCAS avoidance.
Realising that we were the traffic being avoided, I established communication with the other aircraft only to find out that it was also a B-747 and that we had missed each other by less than 400 feet. No sighting was made by either crew.
At that time my companies freighter aircraft were not fitted with TCAS but fortunately the opposite traffic was.
Subsequently, "Incident Reports" were filed but no reply was ever received from the Indian authorities.
