History of the Flight
The pilot, a 71-year-old holder of a Commercial Pilot's Licence with a valid JAA Class 2 medical certificate, arrived at Parham Airfield, West Sussex, a little after 1350 hrs on 29 February 2004. He was asked by the duty tug pilot to take over towing duties and agreed. The aircraft, a Piper PA-25-235 Pawnee registered G-ASKV, had ten gallons of fuel on board. Weather conditions were good with a surface wind of 045° at 10 kt and a temperature of +4°C.
The pilot completed three uneventful aero-tows from Runway 04 at 1424 hrs, 1434 hrs, and 1440 hrs. At 1455 hrs, he commenced a fourth aero-tow with an ASK13 glider (tail number 'DVC') carrying a student and an instructor. The takeoff and initial climb appeared normal. As the combination crossed the airfield boundary, the aircraft began a left turn in accordance with normal club practice. At approximately 200 ft above aerodrome level, the glider crew noticed the aircraft level its wings and fly in an unanticipated direction. The aircraft then started a gentle right turn and descent with the engine at full power. The instructor took control of the glider, released the tow cable, and turned back towards the airfield, completing a successful downwind landing. He then raised the alarm.
The aircraft continued a gentle descent with a right roll, flew over tall trees and a golf course fairway, then collided with more trees. Its forward momentum was reduced by the initial impact, and it descended inverted through the trees, coming to rest inverted. Three witnesses from the golf course attempted to rescue the pilot, opening the cockpit hatch and unfastening his harness, but were driven back by flames and explosions from a fire that started in the engine bay and spread rearwards.
Witness Observations
Multiple witnesses reported that the flight was uneventful until shortly after takeoff when the aircraft appeared to go gently out of control. The engine was heard running at high power throughout. The fire started near the engine almost immediately after impact. The witnesses who attempted rescue saw no sign of consciousness from the pilot.
Post-Mortem and Pilot Information
A post-mortem examination revealed that the pilot had sustained injuries in the accident that were not life-threatening, and there was no evidence of smoke inhalation. The conclusion was that the pilot died before the post-crash fire started, most likely in flight. An abnormality in the pilot's heart was found, suggesting heart failure as the probable cause of death. His most recent medical examination on 12 June 2003 had shown no indications of heart problems. He had a total flying experience of 3,434 hours, with 453 hours on type. He had flown 10 hours in the last 90 days and 6 hours in the last 28 days.
Wreckage Examination
The aircraft made initial contact with trees at a height of approximately 15 metres. The swathe indicated an initial attitude of about 20° right-wing-low, rapidly increasing to inverted. The nose struck a branch, shattering the four-bladed wooden propeller. The aircraft finally struck the ground in a 45° nose-down inverted attitude and burned out. The tow cable was found hanging from branches at the first impact point. Examination showed that the fabric covering had burnt away, both wings were crumpled (right wing more damaged), but the fuselage aft of the engine firewall was intact. The cockpit area was undamaged, and the pilot's restraint system showed no failure, indicating a survivable impact. The aircraft was designed as a crop duster to minimize pilot injury in low-speed accidents. The flying controls were verified intact on site. The propeller fragmentation indicated a high power condition, so no in-depth engine examination was conducted.