What happened
On 23 June 2012, an Aero AT-3 R100, registration G-SRUM, was conducting a local flight from Old Sarum Airfield in Wiltshire. While cruising at 2,800 feet near Langford Lakes, the pilot observed that the right-side cockpit canopy latch had become unlatched. Although the pilot attempted to manually secure the lever, the locking mechanism felt abnormal. Shortly after, the left lever also moved toward the unlocked position.
In an attempt to rectify the situation, the pilot moved both levers back toward the locked position. However, as the aircraft descended to approximately 1,800 feet, the canopy began to open again. The resulting increase in aerodynamic drag made it impossible to maintain altitude. The pilot declared a mayday to Old Sarum Air Traffic Control and initiated a forced landing.
As the aircraft descended toward 300 feet, the pilot identified a suitable field for landing. However, the field contained a tall crop of rape. The aircraft struck the crop, causing the landing gear, fuselage, wings, and canopy to sustain damage, and the aircraft subsequently overturned. The pilot sustained minor injuries.
The investigation
The AAIB investigation established that the pilot experienced a significant loss of aircraft performance due to the drag created by the partially opened canopy. The investigation also noted that the pilot's experience of the event was disorienting; the pilot reported a period of perceived unconsciousness, remembering only being suspended upside down in the harness before exiting the aircraft through the canopy.
Findings
- The primary cause of the forced landing was the unintended unlatching of the cockpit canopy during flight.
- The pilot was unable to maintain altitude due to the increased drag caused by the canopy opening.
- The aircraft overturned during the landing because the tall crop caused the aircraft to dig in.
- The investigation noted a previous similar occurrence involving a different aircraft type where canopy latches had failed in a similar manner.