What happened
On 28 December 2000, an Avioimpex Boeing MD81, registration Z3-ARB, was performing an approach to Runway 14 at Zurich Airport. During the approach, the aircraft overshot the localizer due to a late heading instruction from the approach controller and an incorrect manipulation of the autopilot by the co-pilot. While attempting to return to the localizer, the crew initiated a missed approach.
During this maneuver, the aircraft climbed beyond its cleared altitude, eventually reaching 4700 feet. Simultaneously, a Swissair Airbus A320, registration HB-IJB, had recently departed from Runway 28. The vertical and lateral separation between the two aircraft decreased significantly, reaching approximately 400 feet vertically and 1.0 NM laterally. The crew of the Swissair aircraft reported a TCAS alert indicating an intruder 700 feet above them. The danger was eventually averted when the aerodrome controller confirmed the Avioimpex aircraft would pass behind the departing Swissair flight.
The investigation
The investigation examined the flight paths, air traffic control communications, and the sequence of cockpit actions. Investigators analyzed the aircraft's deviation from the localizer and the specific errors made during the autopilot engagement. The investigation also reviewed the runway configuration at Zurich, noting that Runway 14 and Runway 28 are angled at 41 degrees, which necessitates specific separation intervals between arrivals and departures.
Findings
- The pilot flying on the Z3-ARB performed an inaccurate missed approach, failing to stabilize the aircraft on the runway centerline and climbing without clearance.
- An incorrect autopilot manipulation by the co-pilot prevented the aircraft from immediately intercepting the localizer.
- The departure of the Swissair HB-IJB was not adequately spaced in time relative to the arrival of the Avioimpex aircraft, contrary to ICAO separation recommendations for runways with less than 45 degrees of difference.
- The approach controller's late heading instruction and high speed instruction contributed to the initial localizer overshoot.
Safety action
- The investigation recommends that the responsible authorities establish more stringent regulations for spacing departures relative to arrivals, based on ICAO recommendations, to prevent similar separation conflicts.