Flight History
The private flight intended to travel from Peterborough (Conington) to Inverness, with a planned route via Ottringham and St Abbs VOR/DME beacons. The pilot obtained relevant meteorological information before departure, including terminal area forecasts and area forecasts for Scotland, and determined conditions were suitable apart from some poor weather areas. The Cessna 172 (G-TOME), powered by a single IO-360-L2A piston engine, departed at 1029 hrs UTC and the flight proceeded normally.
The handling pilot acknowledged limited experience and typically arranged for a more experienced pilot on long flights. On this occasion, the right-seat pilot held an FAA Airline Transport Pilot License with 4,475 total hours (200 on Cessna 172 types).
Icing Encounter
North of Dundee, while at FL 50, the crew contacted Scottish Area Traffic Control Centre (ScATCC) at 1248 hrs for a Flight Information Service. Approximately 50 nautical miles from Inverness, the aircraft entered cloud and immediately accumulated ice at a considerable and extremely rapid rate. The Cessna 172 lacks de-icing or anti-icing equipment and is not approved for flight in icing conditions. The right-seat pilot requested Inverness weather, which reported VFR conditions with scattered clouds at 2,800 feet.
At 1256 hrs, the crew requested FL 60 to climb above the cloud, but the aircraft remained in cloud. Ice accumulation increased, airspeed dropped, and the aircraft could not maintain the climb. The pilot then requested a descent to FL 45, calculated as the minimum safe altitude. During the descent, severe turbulence and pronounced downdrafts occurred, with continued ice buildup. Even with full power, airspeed decreased, and the pilot described controls as 'sluggish and appearing to freeze from time to time.' After briefly seeing snow-capped hills below, the pilot decided to attempt a landing before stalling. The aircraft struck the ground at an altitude of 2,690 feet. Upon impact, the aircraft broke up, but all four occupants extricated themselves. The front-seat occupants received minor injuries (a broken wrist and chest pains), while the rear-seat occupants were virtually uninjured.
Search and Rescue
The Lower Airspace Radar Service (LARS) controller at RAF Lossiemouth received an unintelligible transmission mentioning cloud layers and descent from an unknown aircraft. A subsequent transmission revealed only the call sign and 'FL50.' The controller assigned a transponder setting but received no response. After confirming that ScATCC, Inverness, and Aberdeen were not in contact with G-TOME, the supervisor was notified at approximately 1310 hrs. Radio direction finder traces indicated the aircraft was south of Lossiemouth.
A local aircraft attempted airborne relay without success, and another aircraft on 121.5 MHz also failed but reported an emergency locator transmitter (ELT) signal near Ben Rinnes. The Aeronautical Rescue Co-ordination Centre (ARCC) began operations at 1328 hrs. Two Tornado aircraft confirmed the ELT near Ben Rinnes but recovered to Lossiemouth. A Nimrod aircraft located a strong ELT in the Lochnagar area at 1413 hrs. A third ELT was reported in the Dalwhinnie area, but a mountain rescue team found nothing there.
Radar replay from Aberdeen showed contact lost at 1259 hrs on the 155° radial from Inverness at 44.8 nautical miles. A Sea King helicopter reached the nominated Lochnagar position at 1510 hrs and found four walkers in a snow gully, presumed to be from the missing aircraft. The helicopter could not land due to severe downdrafts and low cloud. A second Sea King from RAF Boulmer landed a mountain rescue team near the walkers at 1551 hrs. All survivors were taken to Aberdeen hospital and diagnosed with mild hypothermia.
Meteorological Conditions
At 1200 hrs on 25 January, a low-pressure system west of Scotland produced a moderate to strong, unstable southwesterly airstream. Showers were mainly over western Scotland. The accident site lay adjacent to a boundary between two forecast zones. East of a line from Cape Wrath to Perth, forecast conditions included 25 km visibility, 4 octas cumulus base 2,500 ft tops 6,000 ft, isolated rain showers, and warnings of moderate icing and turbulence in cloud.
An aftercast from the Meteorological Office indicated conditions at the accident site: at 2,000 ft, wind 210°/40 kt, temperature -1°C, dewpoint -3°C, relative humidity 75%; at 4,000 ft, wind 210°/45 kt, temperature -4°C, dewpoint -4°C, RH 98%; at 5,000 ft, wind 220°/45 kt, temperature -6°C, dewpoint -6°C, RH 98%. Cloud was 6 octas cumulus and stratocumulus base 3,000 ft tops 10,000 ft. Moderate turbulence and icing were highly likely.
The first search and rescue helicopter pilot described the scene as having a nearly solid cloud base around 3,000 ft, with snow/sleet showers and a southerly wind of approximately 50 kt at 3,000 ft. He experienced moderate to severe turbulence and downdrafts that occasionally prevented maintaining altitude. As an experienced mountain flier, he would have been very wary of crossing hills below a significant altitude. The Sea King helicopter had limited icing capability and remained clear of cloud.
Emergency Locator Transmitters
G-TOME was fitted with an emergency locator transmitter (ELT) that transmitted on 121.5 and 243 MHz. The Civil Aviation Authority (CAA) requires proof that such equipment will not interfere with other aircraft systems. This ELT was compliant with CAA requirements. Radio distress beacons are categorized by use: ELTs for aviation, EPIRBs for maritime, and personal locator beacons.