A Dassault Falcon 2000 corporate jet was involved in a serious airprox incident with a Hawker Hunter jet, shortly after takeoff from the Swiss airport of Buochs.
On 14 June 2012 at 12:00 UTC, the Falcon 2000 aircraft (OM-OPF), call sign OPJ700, received take-off clearance from aerodrome control at Buochs aerodrome in Switzerland. After take-off, OPJ700 followed its previously assigned standard instrument departure route (SID) WIL1A and climbed to the cleared flight level 100. Approximately three minutes later, a Hawker Hunter jet aircraft registration HB-RVP received clearance to take off from runway 04 from the aerodrome control officer in the control tower of the Emmen military airbase for a flight under visual flight rules. The Hunter was a former military jet, now operated by a Swiss flying museum.
After take-off, HB-RVP turned left onto a south-south-westerly heading and continued to accelerate during its climb.
At 12:07:16 UTC the ground-based short term conflict alert (STCA) system in air traffic control triggered. Shortly afterwards, the traffic alert and collision avoidance system (TCAS) on the Falcon 2000 generated a traffic advisory, followed at 12:07:54 UTC by a resolution advisory which the crew of OPJ700 obeyed immediately. The two aircraft were flying in opposing directions and crossed at 12:08:14 UTC approximately 15 NM south-southeast of radio beacon WIL at flight level 100 with a lateral distance of 0.9 NM and an altitude difference of 400 ft. At this time, the ground speed of OPJ700 was 247 knots and that of HB-RVP was 372 knots.
Visibility conditions were good. The crew of the Hunter were not aware of the dangerous convergence. With the help of the TCAS the crew of OPJ700 were able to establish visual contact with the other aircraft just before they crossed.
The serious incident is attributable to the dangerous convergence of a business jet aircraft in instrument flight and a civil registered fighter aircraft flying under visual flight rules; it was able to occur because of a combination of the following factors:
- With regard to flight operations by civil high-performance aircraft, in particular former fighter aircraft, the supervisory authority requested to adhere to speed limitations and the operator did systematically not comply with because they were convinced that higher speeds were a necessity.
- The measures taken by the supervisory authority after having done a risk assessment were only partially put into practice.
- The high airspeed of the civil registered fighter aircraft increased the closing speed remarkable and reduced the time for traffic information from the air traffic control units involved and made it more difficult for the crews to carry out a visual search and establish visual contact with the other aircraft.
- The two aircraft were not in contact with the same ATC unit.
- The alert from the ground-based conflict alert system was in fact noted by the air traffic control officers involved. Appropriate traffic information to the crew of the business jet was given, but it was too late and imprecise.
- Traffic information to the crew of the civil registered fighter aircraft did not take place.The serious incident was facilitated by the fact that the standard instrument departure route (SID) WIL 1A from Buochs aerodrome was never published. This led to the following contributory factors:
- Two air traffic control units and the crew of the business jet aircraft were unclear about the flight rules governing an aircraft on this SID. This led to discussions on the radio and hence to delayed traffic information.
- The crew of the civil registered fighter aircraft were unaware of the existence of the standard instrument departure route