What happened
On 10 November 2010, a Grumman AA-5A Cheetah, registration G-OPWK, was conducting a training flight departing from Runway 26 at Cumbernauld Airport, Scotland. During the pre-flight phase, the crew identified and drained water from the fuel tanks, and addressed several engine start failures caused by battery issues. After completing necessary engine monitoring, the aircraft departed at approximately 1433 hrs.
Shortly after climbing to an altitude of roughly 600 ft agl, the engine lost power. The instructor, acting as pilot in command, identified a suitable field for an emergency landing. While the student issued a MAYDAY call and the crew performed emergency procedures—including checking the fuel pump and switching fuel tanks—the carburettor heat was not applied due to the limited time available. During the forced landing, the aircraft struck a dry stone wall that had been obscured by long grass. The aircraft came to rest in a wet, boggy field after travelling about 50 m. Both occupants escaped the incident with no injuries.
The investigation
The investigation examined the aircraft's maintenance history, the flight's pre-flight procedures, and the meteorological conditions at the time of the accident. Investigators reviewed the pilot's experience and the mechanical state of the engine and fuel systems. The investigation also focused on the visibility of obstacles in the landing area and the atmospheric conditions conducive to icing.
Findings
- The aircraft sustained damage to the right wing leading edge, a bent right landing gear, and a detached nosewheel, while the stone wall also sustained minor damage.
- At the time of the accident, the temperature was 2°C and the dewpoint was -2°C.
- Serious carburettor icing was highly likely given the atmospheric conditions, which were consistent with icing occurring at any power setting.
- The stone wall was hidden from view by long grass, contributing to the impact during the forced landing.