What happened
On 12 May 2001, a Cessna 182S, registration G-BYEG, was preparing for a private flight from Leicester Airport to Copenhagen. The two occupants, a married couple, had completed their pre-flight inspections and were performing engine power checks. During the take-off roll on Runway 04, the aircraft initially accelerated normally and became airborne after approximately 200 metres.
However, shortly after reaching an altitude of about 100 feet, the aircraft entered an increasingly steep nose-high attitude. This was followed by a gentle left roll at 300 feet, after which the nose dropped sharply. Witnesses observed what appeared to be a stall recovery attempt at low altitude, but the aircraft subsequently dived into a field of oilseed rape near the airfield boundary. The impact resulted in 2 fatalities and the total destruction of the aircraft.
The investigation
Investigators examined the wreckage and found that the elevator trim tab was positioned at or near the maximum nose-up setting. While the aircraft's weight and centre of gravity were within safe limits, the extreme trim position created significant aerodynamic challenges. Testing revealed that at full throttle, the force required to counteract this nose-up trim could exceed 60 lbf, a load that may be too heavy for a pilot to maintain with one hand during the critical climb phase.
An investigation into the Bendix/King KAP 140 autopilot system revealed a potential hazard. If the 'ALT' (altitude hold) button is inadvertently pressed during pre-flight checks, the system engages and attempts to maintain level flight. Because the aircraft is stationary on the ground, the autopilot's auto-trim function will continuously apply nose-up trim until the mechanical limits are reached. This process occurs without any audible warning or prominent visual indication to the pilot.
Findings
- The elevator trim was found at the maximum nose-up position prior to impact.
- Inadvertent engagement of the autopilot's altitude hold mode likely caused the continuous application of nose-up trim.
- The layout of the 'BEFORE TAKEOFF' checklist and the proximity of engine controls to the autopilot buttons increased the risk of accidental activation.
- The physical effort required to overcome the out-of-trim forces during the initial climb was likely beyond the pilot's ability to manage effectively.
Safety action
Following the accident, the AAIB issued several safety recommendations to the CAA and the Cessna Aircraft Company to improve checklist layouts and provide better warnings for unexpected electrical trim activation. In response, Cessna began revising its 'Before Takeoff' checklists to ensure the elevator trim check follows the autopilot status check, and testing of new software with audio alerts for prolonged trim movement was initiated.