Background
On 6 December 2003, a Socata TBM 700B, registration N30LT, crashed 180 metres west of Runway 01 threshold at Oxford (Kidlington) Airport. The aircraft was powered by a single Pratt & Whitney PT6A-64 turboprop engine and had been manufactured in 2001.
The flight originated from Brussels International Airport and was declared as Private by the pilot. However, during the investigation, it was considered that the flight might have been more appropriately categorised as 'Commercial-on-demand'. The aircraft was not certified for such operations by the FAA.
Flight History
The pilot, aged 46, held an FAA Commercial Pilot's Licence with over 1,573 hours total flying experience, including approximately 500 hours on type. Earlier that day, he had flown N30LT from Liege to Brussels with another pilot, who confirmed the aircraft was fully serviceable. After landing, the aircraft was refuelled to full with 640 litres of JET-A1 fuel.
The accident flight departed Brussels at 1017 hrs, cruising at Flight Level 240. Descent began at 1052 hrs, and by 1120 hrs the aircraft was at approximately 2,000 feet amsl. The pilot requested radar vectors to Oxford and was transferred to Oxford Tower at 1122 hrs, reporting visual contact with Runway 01 at three miles. The controller cleared the aircraft to land with a surface wind of 030°/15 kt. No further transmissions were received from N30LT.
Witness Accounts
Numerous witnesses observed the accident. A flying instructor in the circuit saw the aircraft on short finals at about 540 feet agl. He noted a sudden roll to the left to about 60° angle of bank, followed by a pitch-up and continued rolling until impact at about 20° off vertical. The landing gear appeared extended.
Another witness, a flying instructor leaving the airport, saw the aircraft at about 50 feet agl in a normal landing position. He observed a gentle but constant bank to the left, with the nose rising as the bank reached 60°, then the nose dropping and the roll continuing almost through 360° before impact.
A witness on a bicycle reported a considerable increase in engine noise that caused him to look up. He saw the aircraft passing overhead, already banked 40° left, then rolling quickly to more than 90° before the roll direction reversed. The aircraft then turned left 90°, rolled almost level, and suddenly lost height, impacting nose low with slight left bank. He noted the engine noise remained constant and the height about 30 feet agl.
Other witnesses driving near the airport saw the aircraft rolling continuously to the left, with some perceiving it was lower than normal and possibly beginning a go-around.
Weather Conditions
A meteorological aftercast indicated a moist north-easterly flow with clouds few at 1,200 feet, scattered at 1,500 feet, and broken at 2,500 feet. Surface visibility was 10 to 15 km, and the surface wind was 040°/15 kt gusting to 25 kt. The freezing level was at 7,000 feet. A police helicopter crew who arrived at 1144 hrs reported no cloud below 2,000 feet amsl and experienced no turbulence during their approach.
Investigation
The AAIB conducted an extensive field investigation. No technical malfunction was identified that could have caused the uncontrolled roll to the left. The investigation considered that loss of control might have occurred during application of power to adjust the flight path, in an attempted late go-around, or as a result of an unknown distraction. However, no definitive cause was determined.