What happened
On 25 January 2001, a Cessna 172, registration G-TOME, was conducting a private flight from Peterborough (Contington) to Inverness. The flight, operated by a pilot with 78 total flying hours accompanied by a more experienced passenger, proceeded normally until the aircraft entered cloud cover approximately 50 nm from its destination.
Upon entering the cloud, the aircraft experienced rapid and considerable ice accumulation on the wing leading edges. As the Cessna 172 lacked any de-icing or anti-ice capabilities, the crew attempted to climb to FL 60 to escape the icing conditions. However, the weight of the ice and increasing turbulence prevented the climb, forcing the pilot to descend to FL 45. During this descent, the aircraft encountered severe turbulence and pronounced down draughts. The pilot reported that the controls became sluggish and occasionally appeared to freeze. Realizing a stall was imminent, the pilot attempted to land, but the aircraft struck the ground at an altitude of 2,690 feet. The impact destroyed the aircraft, but all four occupants managed to escape the wreckage.
The investigation
The investigation examined the meteorological conditions, the aircraft's performance in icing, and the effectiveness of the search and rescue (SAR) operations. Investigators analyzed the Cospas-Sarsat satellite data and the various Emergency Locator Transmitter (ELT) signals received during the search. The investigation also reviewed the role of the Nimrod aircraft, which used specialized equipment to provide an accurate location of the wreckage, and the challenges faced by the first responding Sea King helicopter due to severe weather and terrain-induced signal interference.
Findings
- The primary cause of the accident was the rapid accumulation of ice on the aircraft's airframe, which the Cessna 172 was not equipped to manage.
- The aircraft encountered severe turbulence and down draughts while attempting to descend through cloud layers.
- The survival of the four occupants was significantly aided by the accurate location data provided by the Nimrod aircraft's detection of the ELT.
- The survivors, including two injured persons, were found suffering from mild hypothermia in a snow gully.