What happened
On 4 July 2011, a mid-air collision occurred at Shoreham Airport involving a Vans RV-6A, registration G-RVGC, and a DA 40D Diamond Star, registration G-CEZR. The G-RVGC was conducting a post-modification test flight, while the G-CEZR was engaged in a training flight.
At approximately 15:27 hrs, the two aircraft collided while operating in the circuit. The G-CEZR was on its crosswind leg, having recently requested a crosswind join for Runway 20. The G-RVGC was on its downwind leg. The impact caused the G-RVGC to become uncontrollable, resulting in a crash into open ground near the Adur recreation ground. The pilot of the G-RVGC sustained one fatal injury. The G-CEZR sustained damage to its propeller, gearbox, and left wing but was able to land safely without further injury to its crew.
The investigation
Investigators examined the wreckage and radar data, which revealed a sequence of three distinct points of contact. The first contact involved the propeller of the G-CEZR striking the tailplane and elevator of the G-RVGC. Subsequent contact between the propeller and the G-CEGC's elevator caused the component to fracture into two pieces. The final contact occurred between the G-RVGC's vertical fin and the leading edge of the G-CEZR's left wing, which caused the fin and rudder to detach from the G-RVGC.
Analysis of the radar tracks showed that the aircraft were on a constant bearing from the perspective of the G-CEZR crew, a geometry that significantly reduces the effectiveness of visual acquisition. The investigation also noted that the G-CEZR was not equipped with a traffic alerting system, despite being capable of such integration.
Findings
- The collision was caused by the failure of the pilots to visually acquire the conflicting aircraft.
- The crew of the G-CEZR did not see the G-RVGC before the collision, and the pilot of the G-RVGC likely did not see the G-CEZR in time to take avoiding action.
- The visual search was likely ineffective because the aircraft were on a constant bearing, making them appear as stationary objects.
- The white composite construction of the G-RVGC made it difficult to detect against the bright horizon.
- The presence of other aircraft in the circuit may have influenced the crew's mental model of traffic positions, potentially leading them to believe no conflict existed.