What happened
On 24 May 2012, a serious airprox incident occurred near Bern-Belp Airport involving two aircraft in Class D airspace. A Fokker 100, registration HB-JVH, operated by Helvetic Airways, was performing a visual approach to runway 32. Simultaneously, an EC 145 helicopter, registration HB-ZRC, operated by Schweizerische Luft-Ambulanz AG (REGA), was transiting the control zone on a VFR flight path.
As the aircraft converged, the air traffic control officer (ATCO) provided traffic information to both crews. Despite the warnings, the aircraft continued on paths that led to a dangerous proximity. The minimum separation between the two aircraft dropped to just 0.7 NM horizontally and 75 ft vertically, qualifying the event as an ICAO Category A airprox. The conflict was only resolved after the helicopter pilot reported traffic in sight and the Fokker 100 crew confirmed they were performing an avoidance maneuver.
The investigation
The Swiss Accident Investigation Board (SAIB) examined the flight paths, radar data, and air traffic control communications. The investigation focused on the effectiveness of the warning systems and the coordination between the flight crews and the tower. Investigators reviewed the technical capabilities of the ground-based surveillance systems and the specific procedures for VFR and IFR traffic within the Bern-Belp control zone.
Findings
- The air traffic controller provided traffic information to both crews, but the convergence was not prevented.
- A critical factor was that the Short Term Conflict Alert (STCA) safety net was not active for the controller because the specific airspace in Bern was configured as an STCA suppression area for altitudes below FL 105.
- The flight crews relied on the 'see and avoid' principle, but the rapid convergence made visual acquisition difficult until the very end of the encounter.
- There was a lack of automated ground-based alerts to warn the ATCO of the impending collision risk.