What happened
On October 3, 2000, near Wil, Switzerland, a Beechjet 400, registration HB-VLW, operating for Sirius AG, was on approach to Zurich. The aircraft was cleared to follow the BERSU 3E arrival route, descending to flight level 120. During the approach, the crew mistakenly turned left toward EKRIT immediately after passing the BERSU waypoint, rather than continuing east toward BASKI as required by the arrival procedure.
At the same time, a Saab 2000, registration HB-IZV, operating as SWR 3774 for Crossair, was climbing out of Zurich following a standard instrument departure. Due to the premature turn by the HB-VLW, the two aircraft entered a dangerous proximity. The separation between the aircraft dropped to a minimum of 2.7 NM laterally and 300 FT vertically.
The investigation
The investigation focused on the flight path deviation and the subsequent air traffic control interventions. The radar controller at the Zurich District Control Center identified the conflict and immediately ordered the HB-VLW to execute an immediate 15-degree right turn. This maneuver prevented a more serious collision and allowed the HB-VLW to cross behind the climbing Saab 2000.
Investigators examined the cockpit procedures of the HB-VLW and the programming of its Collins 850 Flight Management System (FMS). The investigation also reviewed the communications between the air traffic controller and both flight crews, noting that the HB-VLW crew initially believed they were following the correct route.