What happened
On 18 June 2017, a Rotorsport UK Cavalon gyroplane, registration G-GERN, departed Stoke Microlight Airfield in Kent for a private flight to Bedfordshire. The flight was accompanied by one passenger. During the takeoff roll, the pilot applied full power and successfully lifted off, reaching an estimated altitude of between 120 and 150 feet.
Shortly after reaching this height, the pilot observed a rapid decrease in both airspeed and altitude. Due to the low altitude and the proximity of obstacles, the pilot determined that a nose-down maneuver to regain speed was not viable and instead opted for an immediate forced landing on a nearby tidal mud bank located between two jetties. Upon touchdown, the rotor blades struck a moored boat, causing the aircraft to roll over. Both the pilot and the passenger, who were wearing four-point harnesses, escaped the wreckage without any significant injuries.
The investigation
The investigation examined the aircraft's performance capabilities and the environmental conditions at the time of the accident. The weather was notably warm, with ambient temperatures exceeding 30°C, and the aircraft had been parked in a location between two polytunnel hangars, which likely increased the temperature of the fuel.
Technical analysis of the Rotorsport UK Cavalon revealed that the aircraft was flying at approximately 535 kg, only 25 kg below its maximum authorized takeoff weight. Investigators reviewed the takeoff distance requirements, noting that under the high temperature conditions, the required distance to reach a safe climb speed would have likely extended beyond the end of the 475-meter runway. The investigation also considered the possibility of fuel vapour lock or atmospheric disturbances, though the latter was deemed less likely than performance limitations.
Findings
- The aircraft suffered a loss of climb performance due to insufficient runway length to accelerate to climb speed under the prevailing high-temperature conditions.
- High ambient temperatures increased the required takeoff distance and decreased climb performance.
- The pilot's decision to land on the mud bank was a necessary response to the sudden loss of airspeed and altitude.
- The aircraft sustained substantial damage during the landing and subsequent rollover.