What happened
On 13 June 2021, a Grob G103C Twin III Acro, registration G-CFWC, was performing a simulated winch launch failure at Usk Airfield. The flight was intended to re-validate the pilot's use of winch launches. During the ascent, the instructor jettisoned the winch cable at approximately 150 feet to simulate a failure.
Following the cable release, the pilot turned the aircraft to the right, flying away from the airfield to position for a landing in a different area of the airfield. During this maneuver, the aircraft's descent rate increased significantly. As the glider turned back toward the airfield, it had descended too low to safely clear the perimeter. The aircraft struck a tree at the edge of the airfield before hitting the ground, resulting in two serious injuries to the crew.
The investigation
The AAIB examined the wreckage and recovered GPS data from a FLARM unit. The investigation confirmed that the aircraft was structurally intact prior to the impact and found no mechanical defects that would have affected controllability.
Investigators noted that while the pilot believed there was insufficient runway remaining to land straight ahead, witnesses and flight data suggested there was enough distance to land on the existing runway. The investigation also looked into the seat construction, noting that energy-absorbing foam had been placed over standard compressible foam, though it could not be determined if this contributed to the severity of the injuries.
Findings
- The pilot's decision to turn away from the airfield was based on an assessment that there was insufficient runway remaining, an assessment potentially skewed by an inadequate nose-down recovery attitude.
- The glider became too slow to maintain controlled flight and too low to return to the airfield safely.
- The instructor did not intervene early in the maneuver, as they were surprised by the pilot's turn and were focusing on the remaining landing distance.
- The pre-flight briefing for the specific exercise was limited to the aircraft, rather than a more comprehensive session, which might have allowed for a better assessment of the pilot's readiness for the hazardous maneuver.