Synopsis
On 4 September 2010 at approximately 1600 UTC, a Mooney M20J (registration G-JAST) and a Vans RV-4 (registration G-MARX) collided in midair near Ryde, Isle of Wight. Both aircraft were participating in the Merlin Trophy Air Race, which started and finished at Bembridge Airport. The Mooney broke up in flight and fell to the ground; the pilot and passenger sustained fatal injuries. The RV-4 was badly damaged but landed at Bembridge Airport; both occupants received minor injuries.
History of the Flight
The Merlin Trophy Air Race included 20 participants, starting at 1500 hrs using handicap racing procedures. The RV-4 received its start signal at 1529:52 hrs as the sixteenth aircraft, and the Mooney started 15 seconds later as the seventeenth. The race progressed normally, with separation between aircraft reducing over time. On the final turn of the last lap, the RV-4 was overtaken by the last-starting aircraft. Shortly after, the RV-4 crew became aware of the Mooney overtaking from behind and below on their right side. The Mooney moved to the left, then back underneath to the right, before disappearing from view. The RV-4's navigator advised against descending because he had lost sight of the Mooney. The RV-4 crew then felt a sudden thump and saw the Mooney passing down the right side, realising a collision had occurred. The Mooney was no longer pointing in its direction of travel. The RV-4 vibrated severely, and the crew observed damage to their right wing. The RV-4 pilot transmitted a MAYDAY call on 'Bembridge Radio' and decided to fly the remaining four miles to Bembridge Airport. On approach, flaps did not lower symmetrically, so the pilot used the grass runway. The aircraft landed gently, the right main landing gear collapsed, the nose pitched forward, and the left main gear collapsed as the aircraft fell onto its belly. The crew vacated immediately; no fire occurred. Fire crews had deployed to the area where the Mooney was last seen. The Mooney was seen to descend and gyrate, breaking into three main pieces and debris. The main wreckage fell into a wooded area; paramedics arrived but the occupants had not survived.
Witness Observations
A Bulldog pilot also competing in the race, at 700 ft after the final turn, saw the RV-4 pulling away and the Mooney overtaking him. When the Mooney and RV-4 were about 100 m ahead, he saw the Mooney pitch nose-down to about 15° and descend—an abnormal manoeuvre. The Mooney then pitched up to about 15° and climbed through his level into the RV-4. A cloud of dust indicated the collision. The Mooney then pitched, rolled, and yawed, and its tail detached. The Bulldog pilot took avoiding action. He orbited the scene and directed emergency services via ATC. He could not recall any radio transmissions between the Mooney and RV-4 in the minute prior.
Recorded Data
Portable GPS units were recovered from both aircraft, along with a PDA from the RV-4. Two quality data sources (pressure altitude and GPS altitude) were analysed. The RV-4 started takeoff at 1529:55 hrs, the Mooney 14 seconds later. The aircraft completed four circuits, with the Mooney slowly catching up. After the last turn onto the final straight of the fifth lap, the Mooney was below and to the rear and right of the RV-4. The Mooney tracked left and right, descending and climbing in a sequence. The collision occurred at 1606:52 hrs at about 675 ft amsl, over Rowlands Wood, approximately 3.7 nm west of Bembridge's Runway 12 threshold.
Investigation Findings
The investigation determined that the pilot of the Mooney had probably been unable to see the RV-4 for approximately the final 39 seconds before the collision. This assessment was based on GPS data, aircraft attitude, and analysis of the Mooney's window apertures relative to the pilot's nominal eye position. The Mooney pilot sat in the left seat, well away from the right window, restricting view above and to the right. Modelling of window apertures and relative flight paths indicated that the RV-4 was not visible from the nominal Mooney pilot position for 39 seconds prior to impact (with a range of 37 to 44 seconds depending on modelling parameters).