What happened
On 24 August 2019, a Pitts S-2A aircraft, registration G-ODDS, was conducting an aerobatic training flight near Stonor, Oxfordshire. The flight, intended to prepare a student for sports-level aerobatic competition, involved maneuvers likely including spin recovery exercises. Witnesses observed the aircraft enter a spin, briefly recover, and then enter a second, more sustained spin. The aircraft eventually struck the ground in a steep, nose-down attitude. Both the commander and the student sustained fatal injuries.
The investigation
The AAIB investigation focused on the aircraft's flight dynamics, the medical status of the crew, and the aircraft's weight and balance. Post-mortem examinations revealed that the commander had an undiagnosed, significant cardiac condition involving the narrowing of a coronary artery, which could have caused sudden incapacitation.
Investigators also examined the aircraft's center of gravity (C of G). Using data from the commander's computer, it was discovered that the aircraft was operating with an incorrect weight and balance calculation. The actual mass of the aircraft, including the pilots and additional seat cushions, exceeded the permitted limits for both the utility and aerobatic envelopes, and the C of G was positioned further aft than allowed.
Additionally, the investigation identified unapproved aluminum devices attached to the rudder cables. These devices were designed to adjust the rudder pedal position to accommodate pilots of different sizes. While these devices restricted rudder travel by approximately 3°, the investigation concluded they were unlikely to have prevented the recovery.
Findings
- The commander likely suffered sudden incapacitation due to a cardiac condition during the spinning maneuver.
- The aircraft was operating with an aft center of gravity that exceeded permitted limits, which would have reduced control effectiveness and increased the time required for spin recovery.
- The weight and balance calculations used for the flight were inaccurate, failing to account for the true mass of the pilots and the aircraft's updated weight after a propeller change.
- The student, despite having the necessary training, may have been unable to recover the aircraft due to the limited time available, potential disorientation, or a delay in recognizing the commander's incapacitation.
Safety action
Following the accident, the operator implemented several changes to ensure accurate weight and balance management, including:
- Discontinuing the use of spreadsheets in favor of official Aircraft Flight Manual charts.
- Providing scales to allow pilots to verify their actual weights.
- Ensuring current weight and balance reports are included in the aircraft technical log.
- Circulating updated flight manuals and weight/balance information to all instructors.