What happened
On 11 February 2009, two Grob 115E Tutor aircraft, registered G-BYUT and G-BYVN, were involved in a mid-air collision near Porthcawl, South Wales. Both aircraft were participating in Air Experience Flights (AEF) and were operating within uncontrolled airspace. At the time of the incident, the aircraft were flying in a relatively small, restricted operating area. The collision was catastrophic for both airframes, and the investigation determined that successful abandonment of the aircraft would have been unlikely given the altitude and time available.
The investigation
The AAIB investigation examined the flight paths, aircraft visibility, and operating procedures of both aircraft. The inquiry established that both pilots were appropriately qualified and experienced, and that both aircraft were in a serviceable condition prior to the impact. The investigation also reviewed the environmental conditions, noting that while the weather was generally suitable, a layer of low stratus was forming inland.
Investigators analyzed the conspicuity of the Tutor aircraft, noting that their small size and all-white paint scheme made them difficult to detect. Furthermore, the investigation looked into the lack of formal deconfliction procedures and the absence of electronic collision warning systems (CWS) on either aircraft. The study of the aircraft structures also revealed that the canopy design could obscure the view of other aircraft at certain angles.
Findings
- The primary cause of the accident was that neither pilot saw the other aircraft in time to take effective avoiding action.
- The small physical profile and white color scheme of the Grob 115E Tutor significantly hindered visual acquisition.
- The operating area was restricted by local topography and airspace constraints, forcing the aircraft into close proximity.
- There were no formal procedures in place to manage deconfliction between the two flights.
- Structural elements of the aircraft canopy likely obscured the pilots' views at various stages leading up to the impact.
- The aircraft were operating in uncontrolled airspace without the requirement for air traffic control services.