Incident Overview
On 19 November 2008 at 13:23 UTC, a serious incident (AIRPROX) occurred approximately 17 km north of Montreux, Switzerland, near waypoint SOSAL. The incident involved a formation of two Boeing F/A-18 Hornet aircraft operated by the Swiss Air Force, with leader registration J-5004 (call sign Hornet 04), and an Airbus A320-214 (registration HB-IJL, call sign SWR 45NC, flight LX 2811) operated by Swiss International Air Lines Ltd. The Airbus A320 was conducting a scheduled passenger flight from Geneva (LSGG) to Zurich (LSZH) under instrument flight rules (IFR) in Class C airspace. The F/A-18 formation was returning from a training mission and was in the approach phase to Payerne military air base (LSMP), also under IFR.
Sequence of Events
The Airbus A320 was cruising at its assigned flight level along airway N871. Meanwhile, the F/A-18 formation was cleared by the military air traffic controller to descend to the same flight level as the Airbus, despite the formation being on a converging trajectory and rapidly approaching the civil aircraft. The two aircraft were under the responsibility of different air traffic control sectors—civil and military—although both controllers were working in the same control room. The minimum separation standards applicable at the time were 5 nautical miles (NM) or 1000 feet vertically. During the closest point of approach, the horizontal separation reduced to 3.5 NM and the vertical separation to 250 feet, resulting in a loss of separation. The International Civil Aviation Organization (ICAO) classified the incident as Risk B (Safety not assured).
Causes
According to the Bureau d'enquête sur les accidents d'aviation (BEAA), the serious incident was due to the loss of separation between the F/A-18 formation and the Airbus A320 on converging trajectories at the same flight level, caused by a lack of attention of the military air traffic controller, who was absorbed by a side problem.
Contributing Factors
The investigation identified factors that played a role in the incident: the lack of procedures enabling the operation of the Short Term Conflict Alert (STCA) safety net system at military control positions, and the fact that the conflicting aircraft were managed by two different control sectors.
Safety Nets and Communication
The STCA system, a ground-based conflict alert tool, was not available at the military control positions. Onboard traffic alert and collision avoidance systems (TCAS) were installed on both the Airbus A320 and the F/A-18 aircraft, but the report does not specify whether TCAS alerts were generated or acted upon during the event.
Aftermath
The incident was reported to the authorities on 20 November 2008, and the BEAA opened an investigation on 3 December 2008. The final report highlighted two safety deficits, which led to two safety recommendations (numbers 427 and 428), though their content is not detailed in this summary.