Accident Overview
On 10 July 2010, at approximately 1640 UTC, a Stampe SV4C (modified), registration G-BIMO, crashed in woodland near Rotherfield Peppard, Oxfordshire. The aircraft was destroyed and both occupants sustained fatal injuries. The accident occurred during an attempted rolling aerobatic manoeuvre. No technical defects that could have contributed to the accident were identified.
Flight History
The aircraft departed White Waltham Airfield at about 1530 UTC for a local private flight. The owner, a PPL holder, occupied the front cockpit; a friend, also PPL-qualified, was in the rear. A helmet-mounted digital video camera recorded the majority of the flight, including the accident sequence. After climbing to a peak altitude of 3,650 ft (as indicated by the front cockpit altimeter), the aircraft conducted gentle climbing turns and then tracked south before making a 180° level turn north.
The video evidence shows the aircraft pitching nose-down and accelerating to 110 kt at 3,400 ft, then pitching nose-up and stabilising with the nose above the horizon. It then commenced a slow roll to the right. The nose remained above the horizon until the aircraft passed the inverted attitude. The roll continued, but the flight path became spooned, resembling a barrel roll profile. The aircraft departed controlled flight during the roll, developing into an inverted spin that continued for eight turns. Approximately 37 seconds after beginning the roll, the aircraft entered the tree canopy and impacted the ground.
Aircraft Information
G-BIMO was a Stampe SV4C, a two-seat biplane of predominantly wooden construction. Built in 1946 and placed on the UK civil register in 1981, it underwent a major modification in 1995 that replaced the original Renault engine with a de Havilland Gipsy Major 10 Mk 2 piston engine and a Hoffmann wooden propeller. The fuel system featured a single tank in the centre of the upper wing with a flop tube fuel pick-up.
A weight and balance calculation by the AAIB indicated that with the fuel tank more than approximately half-full, the centre of gravity (CG) would have been within limits but the total weight would have exceeded the maximum aerobatic limit. With a low fuel load, the CG would have moved aft, potentially near or beyond the specified aft limit.
Pilot Experience
The aircraft owner, aged 41, held a Private Pilot’s Licence (PPL) and had about 179 hours total flying experience, of which 95 were on the Stampe type. He completed differences training and aerobatics instruction with a qualified instructor, reaching the stage where he was competent in aileron rolls and loops solo. His logbook recorded 21 aerobatic entries, mainly loops and rolls flown as pilot in command.
The passenger, also a PPL holder, had approximately 200 hours total flying experience. Most of his flying was in club-type aircraft, with additional experience in a Jungmann (about 23 hours) and a Harvard (about 14 hours). He had maintained tailwheel currency in a Piper Cub.
Wreckage Examination
The wreckage came to rest in woodland, with evidence indicating the aircraft struck treetops at a very steep flight path angle, with its longitudinal axis beyond vertical. The aircraft was structurally complete at initial tree impact. Damage was consistent with a relatively low descent speed; the four wing surfaces were lightly damaged and geometrically disposed in approximately correct relative positions. The engine was turning at low rpm but delivering some power during impact. The propeller exhibited damage consistent with low rotation speed.
Detailed examination found the flying controls correctly connected, with no evidence of pre-impact failure or control restriction. The fuel system and engine showed no pre-impact failure. The quantity of fuel on board could not be determined.
Medical and Survival
Both occupants held current JAA Class 2 medical certificates. Post-mortem examinations revealed no evidence of significant natural disease. Toxicology results showed both occupants had blood alcohol concentrations below the 20 mg/100 ml legal limit for flying in the UK. Drugs related to emergency medical treatment were detected in the owner.
The owner initially survived the impact and was extracted from the wreckage conscious, but succumbed to multiple internal injuries despite rapid medical intervention. He was declared deceased at 1900 hrs on the day of the accident. The passenger’s helmet, of identical design to the owner’s, lacked a foam liner; the pathologist noted that using the helmet without the liner would significantly reduce impact protection, though its effect on survivability in this accident is uncertain.
Meteorological Conditions
The London Heathrow METAR for 1640 UTC reported wind from 200° at 10 kt, no cloud, visibility greater than 10 km, surface temperature 28°C, and QNH 1016 mb.
Regulatory Context
At the time of the accident, UK regulations did not require pilots to have formal aerobatic training before conducting aerobatics as pilot in command, though the CAA recommended such training. AOPA published training syllabi for aerobatics. In August 2010, EASA proposed an aerobatic rating requirement for flight crew licensing, scheduled to become law in 2012.