Turbulent tripped up by turbulence
PUBLISHED: 13:34 24 June 2011 | UPDATED: 14:06 10 October 2012
Three Tiger Club Rollason Turbulents were practicing a 'limbo' act at Headcorn, making a series of passes at about five feet under a string of bunting held between two poles placed some 50 feet north of the active runway, on which a Cessna 172 was
Three Tiger Club Rollason Turbulents were practicing a ‘limbo’ act at Headcorn, making a series of passes at about five feet under a string of bunting held between two poles placed some 50 feet north of the active runway, on which a Cessna 172 was circuit flying. All the Turbulent pilots had discussed and ‘walked through’ the routine.
The accident aircraft then took off and followed the leader as number two in the procession of three. During a turn for a second pass the pilot of the accident aircraft, who was taking part in his first display season and held a Display Authorisation for the Turbulent, stated he turned slightly inside the leader to avoid flying “unnecessarily in any wake turbulence” and also to “fractionally close the gap between these two aircraft”, then positioned for a straight descending approach to the limbo poles.
After levelling out, he applied full power some 50 metres before the poles, intending to “maximise control authority during the limbo manoeuvre”. His recollection of subsequent events was less clear, but he remembered that immediately prior to passing under the bunting, the aircraft made an uncommanded climb and change of direction. He estimated that it was travelling at 100kt at a height of five feet agl.
Shortly afterwards, the aircraft hit the ground, coming to rest upright, facing 180° to the original flight path with both wings detached and considerable disruption to the cockpit and forward fuselage. The pilot suffered minor injuries. Marks on the ground indicated that the Turbulent had struck in an essentially level attitude, probably touching down first on the starboard main wheel.
There was evidence that the engine had been producing power when the propeller blades hit the ground, but there was no evidence that the aircraft had fouled the bunting. There were several witnesses, including a CAA Display Authorisation Evaluator who was a former member of the team and an experienced pilot of this type of aircraft. In a written statement to the AAIB he noted that the Turbulent had sensitive controls, adding that relaxed control inputs were required to avoid pilot-induced oscillations. He concluded that the aircraft may have encountered the wake of the preceding aircraft in the formation and that the pilot may have over-compensated for the resulting flight path deviation, causing the aircraft to descend and impact the ground.
The crashed Turbulent’s pilot did not see the C172 during the accident because he was concentrating on following the aircraft ahead, but noted that turbulence from the Cessna might have been carried from the runway toward the practice area by the surface wind. He suggested that one way to improve the safety of the activity might be to practice at a location which provided more separation from non-participating aircraft.
The next Turbulent Team practice was held at a different aerodrome, free from other traffic.