What happened
On December 11, 2002, at approximately 18:45 local time, two commercial scheduled flights experienced a conflict near Oslo Airport Gardermoen (ENGM). The first aircraft, an Embraer 145 operating as LOT485, was arriving from Warsaw on a standard arrival route, preparing for landing on runway 19R. The second aircraft, an Airbus A310 registered as AP-BEB operating as PIA752, had recently departed Gardermoen for Copenhagen on a standard instrument departure.
During the approach, the air traffic controller at Oslo APP sector East instructed the departing Airbus A310 to level off at flight level 090 to accommodate traffic. While the controller also alerted the arriving Embraer 145 of an aircraft approaching from below, the crew of the arriving flight experienced a TCAS climb resolution advisory. The Embraer 145 climbed to flight level 110 to avoid the conflict, eventually reporting they were clear of the situation.
The investigation
The investigation examined radar data, air traffic control reports, and communications from both operators. Investigators reviewed the flight path of the departing Airbus A310, noting that while the controller had issued instructions to level off at flight level 090, the aircraft's vertical speed increased significantly during its climb from 7,000 feet. Radar and Mode C information indicated the aircraft reached flight level 093 before descending back to the assigned level of 090.
Findings
- The primary cause of the TCAS resolution advisory was the rapid rate of climb exhibited by the departing Airbus A310.
- The aircraft's vertical speed increased to approximately 4,000 feet per minute during the climb from 7,000 feet.
- Although the air traffic controller had explicitly instructed the departing crew to level off at flight level 090 due to traffic, the aircraft momentarily overshot this altitude, creating the vertical conflict with the arriving Embraer 145.