According to the official, at the time of the incident, National Airlines' flight NCR 840 was on its way to Hong Kong from Bagram in Afghanistan while the KLM Flight KLM 875 was heading to Bangkok from Amsterdam. The Eva Air flight EVA 061 was flying to Vienna from Bangkok, the official said.
"First it was NCR 840, which was flying at flight level 310 (31,000 ft) and EVA 061 at flight level 320 (32,000 ft) which breached mandatory separation. The pilots of both the aircraft were alerted by the onboard TCAS warning system," the official said. Around the same time, the KLM flight was at 33,000 ft, he added.
Following the TCAS (Traffic Collision Avoidance System) warning, the pilot of NCR 840 sought to climb to 35,000 feet but was told to remain at that current level till the time it gets a go-ahead. "However, when the air traffic controller (ATC) observed it climbing, it was immediately asked to take a left turn. In the meantime, EVA also continued climbing at flight level 330, a level at which KLM was already flying, and at this time, another TCAS warning went off, alerting the pilots to steer the aircraft to a safer distance," the official said.
As the NCR 840 again descended to flight level 330, it came across the EVA flight, triggering another TCAS alarm, the official said.
https://www.dnaindia.com/india/repor...planes-2701651
FL 330 KLM 875 ->
FL 320 <- EVA 061
FL 310 NCR 840 ->