Incident Overview
On an evening takeoff at 1820 GMT, after twilight ended at 1756 hours, the aircraft lined up on runway 12. The air traffic controller noted that the aircraft's landing lights were not illuminated during takeoff. The aircraft began its roll after brake release, covering an unusually long distance of approximately 2,300 meters of the available 2,850 meters before liftoff. It climbed with difficulty, and the anti-collision light was observed at low altitude before disappearing behind trees. Five seconds later, a fire lit up the sky.
Impact Sequence
The left wing and left side of the fuselage struck the first trees of a forest at a height of about 22 meters above the elevation, approximately 2,300 meters beyond the threshold of runway 30. The initial impact occurred with the aircraft in a near-level flight attitude and a slight left bank. Subsequently, the aircraft entered a progressive dive with the left wing low, shearing treetops over a traversed distance of about 130 meters before final impact with a creek. At final impact, the aircraft was at an attitude of approximately 25° nose down with a similar left bank angle. The aircraft exploded on impact, and fuel and oil spread across the water surface and ignited. The fire destroyed submerged parts of the wreckage. All 111 occupants were killed.
Investigation Findings
The Commission of Inquiry conducted numerous expert examinations, ground tests, and flight tests but could not determine the absolute cause of the accident due to the wreckage state and its position in an inundated forest area. The commission considered that evidence indicated a possible jamming of an elevator spring-tab mechanism before impact. Flight tests suggested that such a jam would have resulted in abnormal elevator control forces during takeoff, consistent with a prolonged takeoff run and a risk of losing height during flap retraction.
Aggravating Circumstances
The commission highlighted several adverse factors that may have aggravated the circumstances: the implementation of a speed-gaining procedure conducive to low-altitude flight, the failure to maintain a positive rate of climb at the time of flap retraction (which, in the SABENA procedure applied by Caledonian Airways, had no altitude limitation other than obstacle clearance), and the presence of a check pilot in the co-pilot's seat whose attention may have been more drawn to the first pilot's actions than to his own instrument panel. The commission could not eliminate instrument failure as a possible cause because instruments were not recovered or were too damaged for examination.