What happened
On 7 May 2005, a Pierre Robin DR40 and 180R, registration G-BPZP, was performing aero-tow duties for gliders at Lasham Airfield, Hampshire. While completing the second flight of the day, the pilot was on final approach to land on the grass area adjacent to the gliders. Witnesses observed the aircraft at an altitude between 150 and 250 feet as it turned onto final. The aircraft began a right-hand roll that appeared controlled at first, but the roll intensified, leading to a loss of controlled flight. The aircraft impacted the ground in a steep bank, having turned approximately 120 degrees from its original landing direction. The right wing tip struck the ground first, causing the aircraft to cartwheel. This impact caused the engine to separate and resulted in substantial damage to the left wing and empennage, though the cabin remained intact and the pilot sustained only minor injuries.
The investigation
The investigation examined the aircraft's maintenance history and the pilot's recent flying experience. The aircraft had recently undergone an extensive rebuild in France and had completed 75 hours of flight since that check. No pre-impact mechanical failures were identified during the inspection of the aircraft at the local maintenance facility. The pilot, an experienced glider instructor, had completed a check flight with a Class Rating Instructor just one week prior to the accident.
Investigators also examined the tow cable and the environmental conditions. The tow cable's weak links showed no signs of distress, and the cable itself showed no evidence of having snagged on trees. While the pilot initially suspected the cable might have caught on vegetation, witnesses placed the aircraft a safe distance from the tree line. The investigation also noted that a brisk north-west wind of 20 to 25 knots was blowing over nearby trees, creating turbulence near the ground.
Findings
- The pilot's approach speed of 65 knots was lower than the club's recommended speed, which suggested adding half the wind strength to the approach speed to account for the gusty conditions.
- The aircraft likely encountered negative wind shear during the final approach.
- This wind shear caused the right wing to stall, initiating the roll.
- The pilot's attempt to use full opposite controls likely exacerbated the roll into an autorotative maneuver from which recovery was impossible at such a low altitude.