History of the Flight
The pilot, an 81-year-old with 2,160 hours of flying experience (685 on type), flew a Piper PA-25-235 Pawnee (registration G-BDWL) from Crowland Airfield on 1 February 2004 at 1354 UTC. The aircraft, powered by a single Lycoming O-540-B2C5 piston engine, was towing a glider. The pilot had earlier completed a twenty-minute glider flight from a 3,000-foot aero-tow release. An hour later, he relieved the duty pilot on the tug for the final aero-tow of the day. Weather was satisfactory but deteriorating from the west, with surface wind estimated at 210°/15-18 kt, moderate turbulence, good visibility, few clouds at 3,000 feet, and temperature 11°C.
The pilot was described as 'his normal self' while strapping in. Radios were used for communication. The takeoff from Runway 21 was normal, with the combination climbing at about 60 kt to 500 feet. The Pawnee then initiated a gentle right turn. The glider followed as bank increased and climb rate decreased. No changes in engine power or control surface deflections were apparent. The combination descended and accelerated. At approximately 20° bank, the glider instructor took control, called "release", and both he and the student pulled their release toggles. The glider separated at an estimated 300-400 feet agl and about 70 kt, then performed a right-hand circuit and landed safely on Runway 21. The Pawnee continued turning right with increasing bank and descent angle, without apparent control inputs. It struck the ground pitched nose-down by 45° and banked 35° to the right. Witnesses reported the engine sounded at takeoff power throughout. The aircraft was severely damaged but did not catch fire; the pilot did not survive.
Pilot Information
The pilot held a Private Pilot's Licence since 1953 and had accrued 2,160 hours in SEP aeroplanes and 2,400 hours in gliders, in which he was qualified to instruct. He flew regularly and had performed three aero-tows the day before. There was no evidence of handling problems.
Medical: He had a current JAA Class 2 medical certificate, renewed annually due to age. In 2001, his ECG was queried, leading to a cardiological review and an exercise ECG; results were deemed compatible with Class 2. In 2002, another abnormal ECG prompted referral; after a 24-hour ECG showed no abnormalities, he was declared fit with annual cardiology review. In November 2003, he was assessed fit with no further review beyond normal requirements. However, his blood pressure was high and he commenced treatment that month, with additional medication in January 2004. He was advised to inform the CAA of new medication but apparently did not.
Medical and Pathology
Post-mortem examination stated: death due to injuries from the crash; it is likely that the crash was caused by medical incapacitation due to haemorrhage into an atheromatous plaque of a coronary artery. The report noted that appropriate medical screening had been performed, and given that his coronary artery atheroma was not severe and that haemorrhage into a plaque is random and unpredictable, more intensive screening would likely not have prevented the occurrence. His age is a risk factor for cardiac events. The report considered it likely that the haemorrhage triggered coronary artery spasm, leading to cardiac arrhythmia and loss of consciousness. There was no reason to assume that the blood pressure medication contributed to the accident.
Accident Site and Wreckage Examination
The aircraft crashed into cultivated ground adjacent to Runway 27. Initial impact was by the right wing tip, followed by main landing gear and nose marks. Impact track was around 300° magnetic, banked 35° right, and steep nose-down attitude (probably >45°). The aircraft cartwheeled onto the grassed runway, with main wreckage coming to rest erect, nose pointing back along the path, approximately 25 metres from initial impact. The aft fuselage suffered inertial failure. The glider tow rope was found a few metres from initial impact, with the release mechanism having operated, likely due to movement of the release lever during impact. The glass-fibre fuel tank burst but did not cause fire; fuel quantity could not be quantified.
Examination of the flying control system showed no pre-impact failure or disconnect. Flaps were retracted. The engine had torn from mountings but remained attached by cables. The two-bladed metal propeller did not show typical power-on damage (chord-wise scoring, damaged leading edges). Witnesses consistently reported high engine power throughout; absence of blade damage was likely due to steep impact attitude bringing the propeller to an immediate halt and soft clay-based soil with few stones. Some corrosion was found in the right elevator's trailing edge tube near its welded joint with the torque tube; the tube was corroded through almost entire thickness, but the outboard section was in good condition. The extent of corrosion's effect on flight was not specified.
Probable Cause
The crash was likely caused by medical incapacitation due to haemorrhage into an atheromatous plaque of a coronary artery.