What happened
On 10 July 2012, a North American Rockwell OV-10B Bronco, registration G-BZGK, was performing a display practice at Cotswold (Kemble) Airport. The pilot, intending to practice aerobatic manoeuvres, had increased his minimum altitude by 300 feet due to a lack of recent practice. During the sequence, the pilot initiated a barrel roll.
As the aircraft reached the inverted position, the nose dropped below the horizon, and the aircraft entered a steep, uncontrolled descent. Although the pilot attempted to correct the flight path, the aircraft continued to pitch through the vertical. The aircraft struck the ground in an upright, wings-level attitude with a high rate of descent. The impact caused the external fuel drop tank to rupture, triggering an immediate fire. The pilot sustained serious injuries, including spinal damage and burns, but was able to extricate himself from the wreckage before being assisted by responders.
The investigation
The AAIB examined the wreckage, GPS data, and maintenance records. The investigation found that the aircraft was flying at an airspeed of approximately 156 knots, which was lower than the 200 knots suggested by some technical references for this manoeuvre. Investigators also reviewed the pilot's Display Authorisation (DA) and the regulatory framework governing the operation of ex-military aircraft under a Permit to Fly.
Furthermore, the investigation looked into the aircraft's safety equipment, noting that the pilot's shoulder harness failed to restrain him during the impact because the retaining split pin was missing, allowing the harness attachment to pull out of its bracket. The investigation also scrutinized the organisational structure of the operator, where the pilot held multiple key roles, including Chief Pilot and Maintenance Coordinator.
Findings
- The pilot's decision to reduce the roll rate during the manoeuvre contributed to the nose dropping through the horizon before the wings reached the inverted position.
- The low entry airspeed for the barrel roll likely affected the aircraft's performance and manoeuvrability.
- The aircraft's trajectory deviated from the intended display line, moving towards the area where the crowd line would be located.
- Inadequate regulatory oversight regarding the extension of display privileges and the lack of mandatory mentoring for experienced pilots was identified.
- A lack of coordination between CAA departments meant that the overlap between flight operations and maintenance responsibilities was not effectively audited.