The aircraft was approaching Great Massingham Airfield Runway 04 in good visibility with a wind of 340° at 15 kt. The pilot reported a stable approach at 80 kt but, during the flare, the aircraft was ‘hit by unstable air and windshear’. This caused a wing to drop and subsequent flight control correction was insufficient to prevent the aircraft from ‘grounding’ and led to a nose landing gear collapse. The aircraft departed the runway to the left into a ploughed field.
The pilot and passengers were wearing full harnesses and were uninjured. The pilot considered that unstable air at low level from localised terrain led to the loss of control. The pilot had landed at Great Massingham on Runway 22 in the past, but not Runway 04.