What happened
On 9 May 2021, a Stampe SV4C(G), registration G-AWEF, was participating in formation display practice near Headcorn Aerodrome, Kent. The aircraft was part of a four-ship team practicing a new manoeuvre: a synchronised line abreast stall turn.
During the second practice flight of the day, the formation leader initiated a climb, followed by a command to begin the stall turn. While three of the aircraft completed the manoeuvre successfully, G-A/AWEF entered a spin. Witnesses and onboard footage indicated the aircraft rotated several times before striking the ground in a field approximately one nautical mile north of the aerodrome. The pilot sustained fatal injuries, and the aircraft was destroyed.
The investigation
The AAIB examined the wreckage and conducted flight tests using a similar aircraft to understand the departure into spin. The investigation found no evidence of mechanical failure or pre-existing damage to the aircraft. The engine was found to be producing power at the time of impact, and the flight controls were intact prior to the crash.
Flight tests revealed that the aircraft's longitudinal stability was low, meaning small movements of the control column could significantly alter the pitch attitude without obvious tactile feedback to the pilot. Additionally, the rudder does not self-centre, and the high gearing of the rudder bar means even minor foot movements can cause significant surface deflection. The investigation also noted that the pilot's last recorded spin practice was in 2005.
Findings
- The aircraft likely entered a spin because the pilot applied excessive back pressure or failed to neutralise the rudder during the manoeuvre.
- The pilot may have applied aft elevator before the rudder was neutral, or vice versa, leading to the spin.
- The aircraft's altitude was insufficient to recover once the spin developed.
- The lack of recent spin training and the absence of a standardised recovery procedure for this specific manoeuvre contributed to the outcome.
- The aircraft's position in the formation and the complexity of the manoeuvre may have contributed to the pilot's error.