History of the Flight
The pilot and a friend arrived at Full Sutton airfield at about 0830 hrs on 30 April 2016. The pilot had booked the aircraft for two flights: first for general handling and aerobatics, and later to take family members flying. Weather conditions were good with a light westerly wind, visibility exceeding 10 km, and broken cloud at about 3,000 ft. Both the pilot and passenger were students on the Tucano phase of their RAF flying training and had previously flown the Grob Tutor.
After pulling the aircraft out of the hangar, the Chief Flying Instructor (CFI) checked fuel and oil levels while the pilot conducted the pre-flight inspection. The CFI estimated 1.5 hours of fuel in the left wing tank and 1.0 hours in the right, based on a consumption rate of 45 litres per hour during aerobatics. At 0915 hrs, the aircraft was at the holding point performing power checks, then backtracked Runway 22 and departed.
Radar tracked the aircraft climbing through 200 ft after takeoff, turning right toward Castle Howard. Witnesses near the southern part of Castle Howard estate saw the aircraft perform a loop. On the downward half, it appeared to enter a spin. Witnesses reported the engine initially cutting out, then restarting, then cutting out again. The aircraft descended behind a building, and they heard an impact. Other witnesses described a corkscrewing motion before the aircraft struck a plowed field in a steep nose-down attitude, initially with the nose and right wing. Both occupants were found holding the top part of their respective control sticks, which had broken off; the pilot held the left stick with both hands, the passenger the right stick with his right hand.
Aircraft Performance
The Slingsby T67 Flight Manual describes erect spin characteristics: after entry, the aircraft pitches nose up, rolls rapidly, and stabilizes over about 3 turns with a rate of rotation of about 150° per second. The standard erect spin recovery technique involves closing the throttle, raising flaps, checking spin direction, applying full opposite rudder, holding ailerons neutral, and moving the control column progressively forward until the spin stops. Incorrect recovery, such as moving the control column forward before applying anti-spin rudder, can lead to a high rotation rate spin. The manual warns that with the CG at the rearward limit, the pilot must be prepared to move the control column fully forward.
Compared to the Grob Tutor and Tucano, the Slingsby T67 requires the control column to be moved progressively forward for spin recovery, whereas the Tutor and Tucano use a central stick position. An instructor with regular spin recovery training in the Slingsby T67 stated that with correct recovery action, the aircraft recovers from a spin.
Pilot and Passenger Experience
The pilot began flying in November 2009 and flew the Grob Tutor until November 2012, winning an aerobatic trophy. He resumed flying in July 2014 as an RAF student pilot, completing basic training on the Grob Tutor in February 2015 with a total of 152 hours. He completed spinning training in September 2014. In November 2015, he began Tucano training, with 63 hours in the aircraft and 21 hours in the simulator, including spinning training. He held a civilian Private Pilot's Licence with an aerobatic endorsement and a current medical certificate. He had recorded four flights in the Slingsby T67: two dual check flights and two as Pilot in Command. The instructors who cleared him had not conducted spin recovery training in the T67, so he had not received type-specific spin recovery instruction.
The passenger began flying training in August 2015 as an RAF student, accumulating 59 hours on the Grob Tutor, which included spinning and spin recovery training. He started Tucano training on 4 April 2016.
Weight and Balance
Post-accident weight and balance calculations, based on an estimated 40 kg of fuel, gave a total mass at impact of 939 kg and a center of gravity (CG) of 905 mm aft of the CG datum. The CG limits were 860 to 917 mm aft, and the maximum permitted operating weight was 975 kg. The aircraft was within the permitted weight and CG envelope.
Survivability - Parachutes
Neither pilot nor passenger was wearing a parachute. The flying club stated that parachutes were generally available but not required, and were not normally worn in the Slingsby Firefly at the club.