What happened
On the night of the accident, the crew of Post 23 initiated engine start and taxied for departure on runway 23R. The flight was initially planned for a cruise altitude of FL180, but the crew requested and received clearance to climb to FL220 to avoid turbulence. During the climb, the crew maintained high power settings for approximately 15 minutes to compensate for a late departure.
At approximately 22:12, after reaching cruise altitude and reducing power, the captain instructed the first officer to open the fuel crossflow valve. The captain provided several instructions regarding using the aircraft's trim and pedals to manage the resulting lateral imbalance. During this period, the aircraft's horizontal stabilizer underwent automatic re-trimming for 27 seconds as the aircraft transitioned from climb to cruise speeds.
Roughly 47 seconds after the fuel crossflow was opened, the captain noted that the aircraft was not responding well to the adjustment. Shortly thereafter, a "Bank angle" alert sounded, followed by an altitude deviation warning. The aircraft subsequently entered a steep left turn, losing 2000 feet of altitude. Radar tracking ceased at 22:13:45 while the aircraft was descending through FL199.
Witnesses on the ground reported hearing a loud, high-revving noise and observing multiple fireballs descending through the clouds. One witness near the flight path described seeing the nose section and wings separating from the aircraft following an explosion. The main wreckage was located on hilly terrain approximately 7 km northeast of Stratford.
Findings
- The crew operated the fuel crossflow valve to transfer fuel between wing tanks during the cruise phase.
- The opening of the fuel crossflow valve was followed by a sudden bank angle alert and a rapid descent.
- The aircraft experienced a significant loss of altitude and a sharp change in track during the cruise phase.