History of the Flight
On 9 November 2002, at 1500 UTC, a Piper PA-38-112 Tomahawk (registration G-BTOD) departed from Netherthorpe Airfield's Runway 24 for a private flight to Retford (Gamston). The pilot and passenger had arrived from Retford earlier and spent about 30 minutes at Netherthorpe. The aircraft was loaded to approximately its maximum take-off weight of 1,670 lb, with the centre of gravity within limits. The runway was 490 metres TORA (total length 553 metres), with a damp grass surface and an uphill gradient of 1.9%. The pilot set flaps to 21 degrees for a short/soft field takeoff. After a slow taxi onto the runway, he applied full power. The sun shining in his face reduced runway visibility. He raised the nosewheel as soon as possible per soft field technique. At about two-fifths of runway length, the airspeed indicator read 40 kt; at halfway, it still read 40 kt. The pilot considered aborting but dismissed the idea. He anticipated 55 kt by two-thirds of the runway but saw only 46 kt. He attempted to lift off, and the aircraft became airborne approximately 20 metres before a low hedge at the airfield boundary, with airspeed at or below 50 KIAS. The stall warning horn activated for two seconds, and the wheels grazed the hedge. The pilot lowered the nose to accelerate in ground effect, but facing a 7-foot hedge and a barn, he decided to land in the field. The aircraft touched down about 30 metres short of the hedge, then passed through the first hedge at about 55 kt, crossed a road, and cut through the 7-foot hedge before coming to rest in a yard. The impacts tore off the right wing and ruptured the right fuel tank. Within one second, fuel vapour ignited. The pilot and passenger exited the aircraft within about 12 seconds; the pilot sustained minor facial burns, and the passenger suffered serious burns to face and hands. The fire service arrived within five minutes and extinguished the fire.
Weather
At the time of departure, wind was very light. METAR reports from Leeds/Bradford Airport (37 nm north-west) and East Midlands Airport (30 nm south) indicated winds of 1 kt and 0 kt, respectively, 10 minutes before and 20 minutes after the accident. Temperature was approximately 9°C, dewpoint 5°C, QNH 1008 mb. Total rainfall in the previous nine days was 43.8 mm, including 7.4 mm on the accident day.
Take-off Distance Calculation
The Tomahawk flight manual provides take-off distance to 50 feet for a paved, level, dry runway at max weight. Using zero wind, 9°C, and pressure altitude 400 feet, the published distance is 396 metres. A CAA change sheet requires a factor of 1.05, giving 416 metres. Runway 24 was damp grass with an uphill slope. Since the flight manual does not provide correction factors, the CAA Safety Sense Leaflet 7B factors were considered: for a 1.9% uphill slope (factor 1.095), damp grass (factor 1.25), and the CAA safety factor (1.33). Applying these to 416 metres yields 757 metres, exceeding the available take-off distance from Runway 24 (490 metres TORA, with obstacles beyond). The pilot had performed a calculation but mistakenly applied factors to the ground roll distance (213 metres) rather than the distance to 50 feet, and he assumed a dry runway and a 5 kt headwind, not applying the 1.05 factor. His result gave 375 metres ground run, which was less than 490 metres.
Discussion
Given the aircraft's performance, its weight, the weather, and the runway surface conditions, there was insufficient runway length available for the aircraft to become safely airborne. The pilot admitted underestimating the take-off distance required and noted that previous successful departures from Netherthorpe and observing four aircraft depart safely may have affected his judgment. He also stated he should have aborted the takeoff when it was apparent the aircraft was not accelerating sufficiently.