What happened
On 15 May 1998, a Grob G109, registration G-BJZX, was departing Turweston Airfield in Northamptonshire on a private flight. After completing standard pre-flight and holding point checks, the aircraft commenced its takeoff roll. Shortly after leaving the ground, the canopy unexpectedly opened.
In an attempt to manage the situation, the pilot used his right hand to hold the canopy handle down, which prevented him from controlling the throttle. The pilot decided to perform a low-level circuit to attempt a landing, flying downwind at approximately 400 feet. During the approach, the pilot attempted several times to secure the canopy without success. To maintain control while managing the throttle, the pilot released the control column, flying the final approach with only his left hand.
As the pilot attempted to close the throttle for the landing flare, the aircraft dropped abruptly from a height of roughly 15 feet onto the runway. The impact caused the right landing gear to collapse and the propeller to strike the ground. The aircraft slid along the runway before veering onto the grass. There were no injuries to the pilot, though the aircraft sustained heavy damage to the nose, cockpit, and wings, rendering it beyond economic repair.
The investigation
The investigation examined the canopy locking mechanism, which is hinged at the front and secured by a single latch located above and behind the pilot. Post-accident inspections found no mechanical faults with this latching system.
Investigators noted that the club's Chief Flying Instructor taught pilots to verify the canopy was secure by physically pushing upward on the central beam. However, it was determined that the handle could be rotated into the locked position even if the canopy was not fully seated or if the latch was outside the cockpit frame. Furthermore, the investigation considered whether the pilot might have inadvertently unlocked the latch while performing a second set of checks at the holding point.