What happened
On 4 January 2002, a Bombardier Challenger CL-6 and registration N90AG was preparing for a private flight from Birmingham International Airport to Bangor, Maine. The aircraft had arrived from Florida the previous evening and had been parked overnight on the Western Apron. During the morning of the departure, the aircraft was refuelled, and the crew and passengers boarded the aircraft.
At 1207 hrs, the aircraft was cleared for takeoff from Runway 15. The takeoff sequence initially appeared normal, with the aircraft rotating at approximately 146 kt. However, immediately after lifting off, the aircraft began an uncommanded left bank. Despite the crew applying full right aileron and rudder to correct the roll, the bank angle increased rapidly, reaching 50 degrees within two seconds of liftoff.
The aircraft's left winglet made contact with the runway shoulder, and the aircraft continued to track left of the runway heading. As the left wing scraped across the grass, the wing structure deformed and broke apart, leading to a rupture in the fuel tanks. This caused fuel to ignite upon contact with the ground. The aircraft subsequently suffered severe structural damage, including the separation of the empennage, and the main wreckage slid 320 metres while inverted before coming to rest. The accident resulted in 5 fatalities (2 crew and 3 passengers) and the total destruction of the aircraft.
The investigation
The AAIB investigation examined the recovered Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR). Data from the FDR indicated that both engines were operating normally throughout the flight sequence and found no mechanical abnormalities that could explain the sudden roll. The CVR revealed that the crew was operating normally without signs of time pressure, though there was no evidence that the aircraft's anti-ice systems had been activated prior to departure.
Engineering analysis of the wreckage showed that the initial ground contact occurred on the left winglet. The investigation also noted that while other aircraft at the airport had undergone de-icing that morning due to frost or ice accumulation, the crew of N90AG did not request de-icing services.