History of the Flight
On the morning of 9 December 2017, a student pilot arrived at Plaistow Farm Airfield, Hertfordshire, for a planned flying lesson. He met with his instructor, who briefed him for a dual flight conducting circuits followed by a short solo general handling flight if the dual flight was satisfactory. The instructor discussed the increased aircraft performance the student would experience when flying solo due to the reduction in aircraft weight.
At approximately 1145 hrs, the student and instructor took off and completed four circuits, one including a practice engine failure. The instructor reported that the student's flying was good throughout and that no inputs or corrections were needed. After the final circuit, the aircraft was taxied clear of the runway with the engine running while the instructor re-briefed the student for the solo flight. The instructor exited the aircraft, and at about 1230 hrs the student taxied to the threshold of Runway 30 and took off.
Five witnesses observed the aircraft during its takeoff and initial climb. The instructor reported seeing the aircraft rotate normally before losing sight behind buildings. Others reported the aircraft climbing steeply; between 100 and 300 ft agl the left wing dropped and the aircraft turned left. The nose then dropped and the aircraft descended towards and struck the ground in a steep nose-down attitude. No unusual engine noises or engine stoppage were remembered. First responders arrived quickly, but the student had been fatally injured.
Accident Site
The aircraft struck the ground within the airfield on Runway 15/33, approximately 130 m from the threshold of Runway 15. Prior to AAIB arrival, the aircraft had been moved several metres and the wreckage disturbed by first responders. A witness photograph showed the aircraft nose-down in a near vertical attitude with its Brauniger Multi-Functional Display (MFD) and broken perspex on the ground in front. Other items, including the pilot's flight bag, headset, fire extinguisher, and map, had been removed. The battery was removed and the fuel tank selector valve moved to off.
Impact marks indicated the aircraft struck the ground on a heading of 140° (M). Both wings were level, with no evidence of rotation or spinning. Structural tubes supporting the engine mountings failed, and floor tubes were driven into the ground at a 50° angle. There was significant oil in the engine area; two of three propeller blades were broken off. A strong smell of fuel was present.
Aircraft Information
G-CGWL was a Skyranger Nynja 912s, a high-wing, three-axis microlight certified under BCAR Section S. It had conventional flying controls, three-stage flaps, fixed landing gear, and side-by-side seating with four-point harnesses. The aircraft was supplied as a prefabricated kit, constructed of aluminium tubes bolted together, with wings and fuselage braced by cables and covered with Xlam laminate fabric.
Registered on 21 February 2011, it operated on a CAA Permit to Fly administered by the BMAA. The last Permit Certificate of Validity was issued 9 May 2017, valid until 7 May 2018. A flight test on 7 May 2017 recorded engine max static rpm 4,900, climb rate 1,200 fpm at 445 kg, stall speed <32 kt flaps up and down, and approach/landing satisfactory.
G-CGWL was initially built for competition flying, with several BMAA-authorised modifications to save weight, including single rudder pedals, single throttle, fuel flow computer, smaller instrument panel, and a fuel leaning modification. On 28 March 2016, at 484 airframe hours, standard dual rudder pedals and throttle were installed for pilot training.
Flying Controls and Engine
Flying controls were operated by cables and control rods with a single control column between the seats. Rudder pedals controlled rudder and nosewheel steering. Three-stage flaps (up, takeoff, landing) were manually operated and locked by a latch. Pitch trim was manual via a lever between seats, transmitted to a trim tab on the right elevator.
The aircraft was powered by a Rotax 912 ULS four-stroke piston engine driving a Kiev three-blade fixed-pitch propeller through a reduction gearbox. Twin Bing carburettors were modified for fuel leaning in competition. The fuel system comprised two 30-litre polyethylene tanks behind each seat, with a three-position selector valve (off, left, right), in-line fuel filter, and engine-driven fuel pump. An anti-vapour lock return line was fitted. For competition, a fuel computer and additional fine fuel filter were installed, with a bypass valve; standard practice was to fly with the bypass open.
Cockpit Instruments and Stall Warning
The aircraft had a Brauniger Alpha Multi-Function Display (MFD) providing fuel quantity, airspeed, altitude, vertical speed, engine rpm, oil temperature, water temperature, cylinder head and exhaust gas temperatures, and oil pressure. Airspeed and vertical speed were analogue; other parameters numerical. The MFD had visual alerts for exceedances: airspeed below 22 kt or above 150 kt, EGT above 850°C, CHT above 135°C, oil temperature above 130°C, water temperature above 120°C, engine speed above 5,800 rpm, oil pressure below 1.5 bar or above 6.0 bar. An audible alert was not installed. The MFD had a backup battery that provided several hours of power; its voltage was tested and found normal. G-CGWL was not fitted with an artificial stall warning device, as typical for this type.
Aircraft Examination
AAIB examined the aircraft and engine at the accident site and at Farnborough. The aircraft was constructed to a high standard and appeared well maintained. The forward section and cockpit were badly damaged. Both seats and harnesses were intact, but the tube supporting the forward edge of the seats failed in overload. The student, in the left seat, had his harness unbuckled by first responders.
[Note: The source does not list all examination findings; omit unspecified details.]