What happened
On April 26, 2012, a Piper PA-42-720 Cheyenne IIIA, registration D-IOSD, was conducting a private flight from Münster-Oslarück to Buochs. After communicating with the Buochs tower, the pilot was cleared for a right-hand approach to runway 07. However, the aircraft flew west of the airfield and began a descent while turning south and southwest.
Simultaneously, a formation of two Eurocopter AS332 Super Puma helicopters, registrations T-322 and T-314, was returning to Alpnach Airbase. The Alpnach controller cleared the helicopter formation for a left-hand approach to runway 01.
Believing they were approaching Buochs, the pilot of the D-IOSD actually entered the airspace for Alpnach. As the aircraft reached the final approach, the pilot initiated a go-around. During this maneuver, the D-IOSD crossed the path of the helicopter formation, passing approximately 300 ft above the wingman aircraft. While the pilot of the lead helicopter was alerted to the presence of the aircraft by the wingman, the pilot of the D-IOSD did not visually identify the helicopters at any point during the encounter.
The investigation
The investigation examined the flight paths, communication between the Buochs and Alpnach control towers, and the availability of surveillance technology. Investigators found that the pilot had misidentified the airfield, leading to an uncoordinated approach into the path of the military helicopters. The investigation also looked into the technical capabilities of the local air traffic services and their access to surveillance data.
Findings
- The primary cause of the near-collision was the pilot's lack of situational awareness, which resulted in the confusion between Buochs and Alpnach airfields.
- The pilot failed to develop an effective approach concept, leading to the unintended entry into Alpnach's traffic pattern.
- A systemic contributing factor was that the air traffic control positions at both Buochs and Alpnach lacked access to radar data that could have identified the aircraft's actual trajectory.
Safety action
Following the incident, a safety recommendation was issued to the Federal Office of Civil Aviation, the Swiss Air Force, and Skyguide. The recommendation emphasizes the need to provide regional and military air traffic control towers with access to existing radar data to improve situational awareness and prevent similar occurrences.