History of the Flight
The aircraft, a De Havilland DH82A Tiger Moth (registration G-BYTN, serial number 3993, year of manufacture 1939), was operated by a company specialising in scenic experience flights. On 16 April 2015, the pilot had flown the aircraft four times that day, and the aircraft itself had flown six times. The pilot and a passenger were taking off for a pleasure flight in the local area. The aircraft had full fuel and was just below its maximum takeoff weight (MTOW) of 828 kg, with a passenger weighing 101 kg.
The pilot elected to use grass Runway 24, which has a Takeoff Run Available (TORA) of 490 metres and a 1.9% upslope, as there was no discernible wind. After his second flight of the day, an observer had advised him to use more of the TORA, believing he was starting from the intersection with cross runway 18/36. The pilot assured the observer he was starting adjacent to the runway numbers and resolved to start further back on subsequent takeoffs.
Accident Sequence
After refuelling and briefing his passenger, the pilot started the engine and backtracked along the southern side of Runway 24 to position the aircraft just before the beginning of the displaced threshold arrow. The first part of the takeoff run seemed normal; he let the tail rise. The aircraft then struck an undulation and briefly became airborne but touched down again despite the pilot’s attempt to stay airborne. He tried again, having used about 250 metres of the runway (compared with about 175 metres on previous takeoffs). Conscious of the extra weight, he briefly allowed the aircraft to stay in ground effect to accelerate before raising the nose to climb away. At that point, the pilot felt a general lack of energy and the climb rate reduced. He glanced at the airspeed indicator and recalled it reading 36-37 kt, so he lowered the nose to try to regain energy, which caused the aircraft to sink. He later noted from his GPS that he had reached a maximum height of 20 ft (though it appeared to him at the time more like 30-50 ft).
Aware that the aircraft was sinking and that there were buildings and hedgerows ahead hidden underneath the nose, the pilot decided to put the aircraft down in a field of oil seed rape at about his 11 o’clock position. He touched down in the field but was still applying left bank to steer away from a hedgerow. The left lower wingtip brushed the crop and then the ground. In trying to straighten up, the right lower wingtip and the main landing gear struck the ground, causing the aircraft to flip inverted at a speed the pilot estimated to be about 35 kt.
Aftermath
The passenger evacuated the aircraft first, followed by the pilot. Neither sustained injury. The aircraft suffered severe damage to the lower right wing, fin, and propeller, with possible distortion of the fuselage. The pilot believed that a slight reduction in available power, coupled with calm wind conditions and the short runways at Netherthorpe, contributed to the accident. He advocated a more restrictive weight limit than the MTOW when operating from Netherthorpe in calm conditions and noted anecdotal evidence that the Tiger Moth’s Gipsy engine was prone to a reduction of available power when operating continually over a lengthy period due to heat build-up. However, both organisations with type responsibility for the Tiger Moth and Gipsy engines stated they are not aware of such an issue with correctly set up and maintained engines.