What happened
On 11 August 2007, a Dragon 200 aircraft, registration G-MMAE, departed from Sandown Airport on the Isle of Wight for a short flight intended to demonstrate the aircraft to potential buyers. The flight commenced from Runway 23, a grass strip with a slight upward gradient.
During the initial climb, while maintaining an airspeed of approximately 30 mph at an altitude of 50 feet, the aircraft encountered turbulence. This caused the right wing to drop; although the pilot corrected the wing drop, a second drop occurred. Following this second disturbance, the aircraft began to descend. Despite the engine remaining at full power, the pilot found the aircraft unable to maintain altitude. Realising the aircraft could not clear obstacles beyond the runway boundary, the pilot elected to perform a forced landing. The aircraft struck the ground in a level attitude beyond the runway, resulting in a collapsed undercarriage and a damaged propeller. The pilot and passenger were uninjured.
The investigation
The investigation examined the aircraft's performance capabilities and the environmental conditions at the time of the accident. The aircraft was operating at a takeoff weight of 373 kg, which was near its maximum allowable weight of 384 kg.
Analysis of the aircraft's engine performance revealed that during a previous flight testing session in April 2007, the aircraft had achieved a climb rate of 333 fpm at a much lower weight of 292 kg. Calculations performed by the aircraft designer suggested that at the heavier takeoff weight of 373 kg, the climb rate would be significantly reduced, potentially as low as 30 fpm. This performance level would have resulted in a climb gradient of only approximately 1%, which was insufficient to overcome the rising ground beyond the airfield boundary when combined with the encountered turbulence.
Findings
- The aircraft was operating at a weight close to its maximum authorized takeoff weight.
- The pilot was maintaining an airspeed of 30 mph, which was below the recommended climb speed of 35 mph for an airspeed indicator calibrated in mph.
- The aircraft encountered turbulence or a downdraft that exceeded the aircraft's diminished climb capability at its heavy takeoff weight.
- The engine may not have been delivering full power, as evidenced by performance data from previous flight testing.
- The aircraft was flying towards rising ground, leaving no margin for error during the climb.