What happened
On 6 June 2013, a Cirrus SR22, registration N936CT, was conducting a private flight from Denham Aerodrome to Gloucestershire Airport. During the approach to Runway 27, the pilot encountered a high-workload environment due to a runway change and a delay in being cleared to descend.
While on final approach, the autopilot was disconnected and subsequently re-engaged. Upon re-engagement, the automatic flight control system (AFCS) reverted to default pitch and roll hold modes. The pilot, unaware that the flight modes had changed, attempted to manually override the aircraft's bank. This led to a series of oscillations in pitch, roll, and airspeed. As the aircraft deviated from the approach centerline, the pilot's attempts to correct the flight path resulted in over-controlling the aircraft.
As the aircraft entered cloud cover, the pilot became disoriented. Following a period of extreme flight path deviations, including a rapid descent and significant airspeed fluctuations, the pilot determined that the aircraft could not be safely recovered and activated the ballistic recovery system (BRS). The parachute deployed, and the aircraft came to rest in a suburban garden. There were no injuries to the pilot, though the aircraft sustained substantial damage to its fuselage and wings.
The investigation
The AAIB examined the aircraft's Garmin G1000-based avionics, specifically analyzing data recovered from an SD card and a Recoverable Data Module (RDM). The investigation focused on the sequence of autopilot disengagements and the subsequent flight path deviations. The investigators also reviewed the pilot's training history, noting that while the pilot had practiced BRS deployment in a simulator, they had not specifically trained for the use of the aircraft's automatic leveling function.