What happened
On 25 November 2019, a Cessna 172S, registration G-CBXJ, was performing a local flight from Caernarfon Airport when it descended into the sea near Puffin Island, resulting in 1 fatality.
The pilot had intended to fly a short route via Great Orme and Puffin Island. Following a minor delay due to a failed starter motor repair, the aircraft departed at 1115 hrs. After contacting RAF Valley ATC, the aircraft was tracked via ADS-B technology flying along the coastline. However, around 1205 hrs, the aircraft disappeared from flight tracking feeds. A search operation involving lifeboats and a rescue helicopter later located wreckage, including the right wing and engine, approximately one mile off the north-east tip of Puffin Island.
The investigation
The AAIB examined the wreckage via Remotely Operated Vehicle (ROV) and analyzed ADS-B flight data. The investigation included a flight trial using a similar Cessna 172S to replicate the final descent profile. The trial assessed the aircraft's longitudinal and lateral stability, as well as the physical force required to maintain a specific descent rate.
Investigators also reviewed the pilot's medical history and recent health, noting a recent bout of illness. Maintenance records were checked, and radio communications were tested for potential coverage gaps. The investigation also looked for evidence of engine failure or structural issues by examining the state of the control surfaces and the engine's performance during the flight trial.
Findings
- The aircraft's descent profile, characterized by a steady increase in rate and a specific heading change, indicated that manual control inputs were likely required to enter and maintain the descent path.
- Flight trials ruled out a full or partial engine failure as the cause of the descent.
- There was no evidence of structural failure or disconnected control linkages.
- While the pilot had recently been unwell, post-mortem and toxicology results showed no evidence of medical incapacitation, though it could not be entirely dismissed.
- The aircraft was found to be within its permitted weight and center of gravity limits for the flight.