What happened
On 24 October 2007, a serious airprox incident occurred approximately 2.4 NM north-northeast of the Kloten beacon. A Boeing 737-300, registration D-ABXY, operated by Deutsche Lufthansa, was performing an ILS approach to runway 14 at Zurich. During the approach, the crew aborted the landing due to technical issues and initiated a missed approach procedure, climbing to a standard altitude of 5000 ft.
Simultaneously, an Airbus A320-200, registration JY-AYF, operated by Royal Jordanian Airlines, departed from runway 10 on the VEBIT TWO ECHO standard departure route. As the Airbus climbed through 4800 ft, it began a left turn that crossed the centerline of runway 14. This maneuver brought the two aircraft into a dangerous convergence. The Traffic Alert and Collision Avoidance System (TCAS) issued a Traffic Advisory (TA) followed by a Resolution Advisory (RA) to both flight crews. The closest point of approach occurred at 12:39 UTC, with a lateral separation of only 1.1 NM and a vertical separation of 600 ft, failing to meet the required minimums of 3 NM or 1000 ft.
The investigation
The investigation conducted by the AAIB examined the flight histories, air traffic control (ATC) procedures, and the runway utilization concept in place at Zurich. Investigators analyzed the coordination efforts between aerodrome control and terminal control, specifically focusing on how the 'Bise' wind conditions influenced runway usage. The inquiry also reviewed previous safety clarifications and the adequacy of controller training regarding the specific conflict points created by the runway 10 departure route and runway 14 missed approach procedures.
Findings
- The incident was caused by the inadvertent convergence of a departing aircraft and an aircraft performing a missed approach.
- There was no established procedural separation between the standard departure route from runway 10 and the missed approach procedure for runway 14.
- The runway 10 utilization concept imposed a high workload and coordination burden on air traffic controllers.
- Existing safety assessments had failed to adequately identify the hazard of this specific convergence.
- Air traffic controllers were not sufficiently trained for this specific conflict scenario and were surprised by the situation.