What happened
On 27 August 2024, a Grob 109B touring motor glider, registration G-CHYB, was performing a final approach to Aston Down Airfield in Gloucestershire when it experienced a sudden and rapid pitch-down. The aircraft struck trees approximately 100 feet above the ground before sliding onto the A419, a busy main road, where it came to rest and blocked traffic for several hours.
The flight was a private operation involving the pilot and a passenger. The passenger, an extremely experienced glider pilot, had been given control of the aircraft during the flight. As the aircraft transitioned into a gliding-mode approach, the passenger moved to the right seat. During the final stages of the approach, the passenger attempted to correct what they perceived as a low altitude. However, this resulted in a severe nose-down movement that could not be corrected before impact. The aircraft sustained damage beyond economic repair, and while the pilot escaped with minor injuries, the passenger sustained a serious spinal injury.
The investigation
Investigators examined the cockpit configuration and the passenger's control habits. In the right seat of the Grob 109B, the airbrake lever is located on the right-hand side of the cockpit. This differs from the passenger's standard experience in most unpowered gliders, where the airbrake is typically operated with the left hand while the right hand manages the control column.
The investigation also reviewed the sequence of events leading to the impact. It was noted that the passenger had significant experience in various glider types but had no prior experience operating this specific aircraft from the right seat. Furthermore, the pilot had not provided a specific briefing on the aircraft's handling for this flight, as they were not acting in an instructional capacity.
Findings
- The passenger's established habits from flying conventional gliders led to inappropriate control inputs.
- While attempting to reduce the rate of descent, the passenger likely pushed the airbrake lever forward instead of retracting it, or applied the wrong hand to the control column, causing the aircraft to pitch down sharply.
- The side-by-side seating arrangement of the Grob 109B reversed the expected control layout for a right-seat occupant compared to standard tandem gliders.
- A startle response prevented the crew from implementing corrective measures within the 1.5-second window between the pitch-down and the collision with the trees.