History of the Flight
On 28 October 2004 at 1430 UTC, a Piper PA-28-151 Warrior, registration G-BDGM, was departing from Runway 24 at Netherthorpe airfield in Yorkshire. During the engine run-up, the pilot noticed a significant drop in RPM when operating on one magneto. Suspecting moisture in the ignition system, he leaned the mixture and continued running the engine to rectify the problem. After the engine appeared to run normally, he lined up for departure.
The pilot employed a short-field takeoff technique, setting two stages of flap and applying full power against the brakes while the aircraft was stationary. The engine produced approximately 2,200 RPM at full throttle. Upon brake release, acceleration seemed normal, with RPM rising as airspeed increased.
With about 150 metres of the marked runway remaining, the pilot realised the aircraft would not reach flying speed and aborted the takeoff. He retarded the throttle and applied the toe brakes. Judging that the aircraft would not stop before the airfield boundary, he raised the nose slightly to cushion the impact. This caused the aircraft to become airborne very briefly before striking a hedge and catching fire.
The pilot, wearing a lap and shoulder harness, suffered light bruising and whiplash. He turned off the battery master switch and fuel before exiting the aircraft. The airfield fire crew, who had been watching the departure, arrived shortly after the aircraft came to rest and quickly extinguished the fire using foam.
Airfield Description
Netherthorpe has four grass runways. Runway 06/24 is 553 metres long with a take-off run available (TORA) of 490 metres and slopes uphill with a gradient of 1.9% in the Runway 24 direction. Markings showing the south-western end of Runway 24 are placed approximately 146 metres from the airfield boundary. Runway 18/36 has a total usable length and TORA of 382 metres. The airfield is considered challenging by many users, and the operator insists on briefing unfamiliar pilots before their intended flight.
Before departure, the pilot noted that Runway 24 was in use by other aircraft and decided it was the most favourable runway for departure in the prevailing conditions. At the time of the accident, the unofficial airfield weather report gave a southerly wind at 10–15 kt and a temperature of 10°C. The pilot assessed the runway as damp.
Aircraft Performance
The operator provided performance and weight and balance information for G-BDGM, a PA28-151, the least powerful of the Warrior family. The maximum permitted takeoff weight is 1,054 kg. With approximately 98 kg of fuel and one pilot onboard, the estimated all-up weight was 857 kg.
According to the flight manual, at this weight from a dry, level, paved runway, the takeoff run required (TORR) is about 400 metres, and the takeoff distance required (TODR) to clear a 50-foot obstacle is 497 metres.
Safety Sense Leaflet (SSL) 7B, published by the CAA, advises increasing takeoff distance required by 30% for wet grass and by a further 10% for an uphill slope of 2%, yielding a TODR of 707 metres. Using the same factors, the TORR would be 570 metres. However, the effect of slope and surface condition is proportionally greater on the ground run than on the overall takeoff distance, so the actual TORR is likely greater than 570 metres. SSL 7B further recommends increasing TODR by 33% as required for Public Transport flights to account for variations in technique, aircraft condition, and environmental factors, giving a TORR of at least 758 metres and a TODR of 940 metres.
Engineering Inspection
After the aircraft was recovered to the airfield parking area, the engine was removed and taken to a repair facility. The magnetos were returned to the manufacturer before inspection could occur. Inspection of the remaining components did not reveal any condition that might have contributed to the rough running experienced during the run-up.
Conclusion
It was not possible to determine if the engine was producing normal power during the takeoff run. Even if it was, it is likely that there was insufficient runway available for a safe departure in the prevailing conditions.
The pilot reported that, although he considered the runway suitable for a safe takeoff, he thought the accident might have been caused by a combination of the runway state, the prevailing conditions, and a reduction in engine performance that was not obvious at the start of the takeoff run.