At 13:30 hrs the aeroplane departed from Bahrain airport for a cargo flight to Brussels with one intermediate stop at Bergamo Italy. Two pilots were aboard the aircraft. The intermediate landing at Bergamo was conducted at 19:10 hrs after a flight time of 05:40 hrs, the departure to continue the flight to Brussels was at 21:06 hrs.
With the change to the ACC Zurich at 21:20 hrs the aeroplane was guided on the frequency 128.050 Mhz with the transponder code A 7520. A clearance for a direct approach to the Tango VOR as well as for a climb from FL 260 was granted. The crew asked for a clearance to climb to FL 360, which was given app. 4 minutes later (at 21:26:36 hrs). At 21:29:50 hrs the aeroplane reached this flight level.
At 21:34:42 hrs the airborne TCAS warned the crew against probable conflicting traffic. 14 seconds later (21:34: 56 hrs) the crew received the TCAS command to descend a further 14 seconds received the command to increase the descent (“increase descent”). At 21:35:19 hrs the crew reported to ATC the avoidance command (“TCAS descent”).