What happened
On 31 May 2020, a Cirrus SR22, registration G-CTAM, was conducting a private flight from Lee-on-Solent to Dunkeswell before attempting a return leg. During the descent toward Lee-on-Solent, the engine began to run roughly and subsequently lost power. The pilot, unable to reach an airfield, turned the aircraft parallel to the shore and activated the Ballistic Parachute Recovery System (BPRS).
The aircraft struck the sea near Calshot Spit at a descent rate of approximately 1,500 feet per minute with a nose-down pitch of 74 degrees. Despite the impact, the aircraft remained upright long enough for the two occupants to exit via the right door onto the wing. Both the pilot and the passenger escaped uninjured, though the parachute eventually caused the inverted aircraft to drift toward the shore.
The investigation
The AAIB investigation focused on the cause of the engine power loss and the circumstances leading to the ditching. Analysis of the Multi-Function Display (MFD) and Primary Flight Display (PFX) data revealed significant fluctuations in fuel flow, with the flow dropping to levels insufficient to sustain combustion.
While the aircraft's fuel tanks were found to contain very little fuel upon recovery, investigators noted that sea water had entered the system, and the aircraft's inverted position in the water could have caused fuel to drain through the vents. The investigation also examined the pilot's fuel management practices, noting that the pilot used a timer to switch fuel tanks every 20 minutes to maintain balance.
Findings
- The loss of power was probably caused by fuel starvation, though the specific mechanism—whether a tank ran dry or a leak occurred—could not be definitively established.
- If a tank had run dry, the engine might have failed to recover properly because the pilot did not select the fuel pump to the boost position during the tank switch.
- The aircraft's fuel indication system, which relied on analogue float sensors, may have provided inaccurate readings, and the pilot did not rely on the physical fuel gauges for verification.
- The BPRS was deployed at an altitude of approximately 340 feet, which was too low to allow the deployment sequence to complete the transition to a level attitude before impact.