History of the Flight
The accident occurred when a Cessna F150J (registration G-INGR) and a Yak Aerostar (registration RA02030) collided in the circuit at North Weald Airfield on 19 April 2000 at 1621 hours UTC. The weather at North Weald was observed as wind 200°/15 kt, few clouds at 3,000 feet, with unlimited visibility.
The Yak pilot was a member of a seven-aircraft formation aerobatic team operating from North Weald. After a pre-display briefing, the team conducted a display rehearsal over the airfield between 1510 and 1520 hours. Following the rehearsal, the Yak, in company with another aircraft, departed for Little Gransden, Cambridgeshire, to collect a 2.5-metre length of metal braided hose for the smoke generator system. The Yak arrived at Little Gransden at approximately 1540 hours, and the pilot placed the hose inside his flying suit before departing for North Weald at about 1600 hours. Radar recordings showed the Yak transiting from Little Gransden directly west of Harlow, then routing south of the town heading east towards North Weald. The altitude during transit was not recorded.
The Cessna owner had travelled to North Weald with his family and a friend, a professional pilot who had taught him to fly. The friend, the pilot of the Cessna, intended to conduct a short local flight with family members. After pre-flight checks, the Cessna pilot and one of the owner's children taxied to book out. The Cessna took off from North Weald on Runway 20 (right-hand circuit) at approximately 1600 hours and departed to the southeast from the end of the downwind leg. Radar primary returns showed the flight path to the southeast, including left and right turns. The aircraft then travelled west, passing south of North Weald, and joined the circuit on the downwind leg at 1619 hours.
The Collision
At 1620 hours, the Yak pilot, approaching the circuit from the west, called North Weald Radio: "Aerostar initial er break to land." The radio operator saw the aircraft at about circuit height and responded, "Roger one aircraft late downwind." The Yak pilot confirmed he had the Cessna in sight: "Visual with him and er thirty seconds to initial." The term "initial" was used by the formation aerobatic team to signify the initial point before running in for the break.
At that time, the Cessna was approximately 1.5 nautical miles south of the Yak, which continued on an easterly track to pass in front of the Cessna. Shortly after the last transmission, the radio operator saw the Yak enter a dive, level at about 100 feet momentarily, then enter a climbing turn. A witness near the aircraft track observed the turn to the left. The Cessna then made a right turn onto base leg. Radar data indicated the Cessna's average ground speed was 87 knots and the Yak's was 124 knots. The Yak climbed back to approximately circuit height and transmitted: "Aerostar 4 is initials for the break and the other traffic is?" The radio operator waited for the Cessna pilot to respond but heard no transmission and could not see both aircraft.
An off-duty Air Traffic Control Officer observed the Cessna on a constant easterly heading at about circuit height. He saw the Yak initially in straight and level flight on a southwesterly heading, then make a gentle left turn with 5° to 10° of bank, as if turning towards North Weald, at about circuit height with engine power at low to medium setting and the nose slightly above the horizon. Just before the collision, the Cessna made a very rapid roll to the right to a steep bank angle; about one second later, at 1621:44 hours, the two aircraft collided.
The right wing of the Cessna detached, and the aircraft descended rapidly in a right spiral, impacting the ground in an open field. The Yak also made a steep descent, impacting in another field 150 metres south of the Cessna. The occupants of both aircraft received fatal injuries in the impacts.
Wreckage Examination
The two aircraft wreckages were relatively close together. The Cessna's right wing, nearly complete from root to tip with strut attached, was found 185 metres north of the main wreckage. Pieces of windscreen and loose items from the Cessna were nearby. The fuselage, empennage, and left wing impacted the ground in a steep nose-down attitude, buckling the rear fuselage through almost 180°.
The Yak struck the ground in a steep nose-down attitude beyond vertical at high speed, leaving the engine and nose buried. Severe damage to the right tailplane and elevator, not consistent with ground impact, was noted. There was a propeller slash on the inboard right wing. Apart from missing tailplane parts and the fabric-covered elevator (found with the Cessna windscreen debris), the Yak appeared structurally complete at ground impact.
The propeller slash in the Yak's right wing was generated from the underside. A black mark on the underside wing skin matched the Cessna's black painted spinner, confirmed by a piece of spinner found with rivet witness marks matching the Yak wing's rivet pattern. On the Cessna, the only damage severe enough to cause right wing attachment failure was on the strut and underside skin of the leading edge adjacent to the strut attachment. The skin had been crushed from underneath, leaving a black smear. The strut received a heavy blow from behind, leaving faint traces of blue and yellow paint.
The close proximity of the wreckages suggested both aircraft became uncontrollable immediately after collision. The Cessna's loss of its right wing made this unavoidable. Major collision damage to the Yak was confined to the right tailplane and elevator; whether this rendered it totally uncontrollable is not known, but appears likely. The propeller slash continued into the aft fuselage but was shallow and aft of the pilot's seat, so pilot incapacitation from it does not appear likely. Given the low altitude, there was little time for the Yak pilot to abandon the aircraft using his parachute, and no attempt was observed.
The damage indicated a relatively "glancing" impact, as a more direct impact would have caused more airborne fragmentation. Although most witnesses described the Yak striking the Cessna's left wing, no evidence of such impact was found. Damage to the Cessna's right wing and strut came from below and behind. Macroscopic and forensic examination of witness marks suggested the aircraft were effectively "belly-to-belly" and heading generally in the same direction at impact. Marks on the Cessna right wing and strut matched the Yak's tailwheel and lower rudder; black marks on the Yak's elevator lower surface fabric matched Cessna tyre rubber; and the propeller slash on the Yak's right wing underside confirmed the relative attitudes. It is concluded that the Yak pilot also tried to take avoiding action by banking very rapidly to the left.
Airfield Joining Procedures
North Weald Airfield is an unlicensed aerodrome operated by the local authority. It is situated south of Stansted, beneath the Stansted Control Area (1,500 to 2,500 feet altitude) and some 2 nautical miles outside the Control Zone (surface to 3,500 feet). Flying activity includes model aircraft, light aircraft, ex-military jet types, parascending, and gliding. The Airfield Operations Manual (AOM) sets out joining procedures for powered fixed-wing aircraft. Aircraft are permitted to join North Weald only in accordance with these procedures, which are published in the UK Air Pilot and Jeppesen Bottlang Airfield Manual.