Incident Details
On 2 May 1997, at 0755 UTC, Swissair flight SR 101, a Boeing 747-357 (registration HB-IGE), landed at Zurich Airport and subsequently taxied to parking position A-48. While turning left toward the stand, the crew observed a cleaning truck parked relatively close, though outside a red marking line. The pilot-in-command (PIC) reduced taxi speed to allow the copilot to monitor the clearance between engine No. 4 and the truck through the right cockpit window. The copilot judged the distance to be insufficient and called for the PIC to stop. The PIC did not fully halt the aircraft, and the cowl of engine No. 4 made contact with the truck's cab. Upon a second call to stop, the PIC applied brakes, bringing the aircraft to an immediate halt.
Investigation Findings
The aircraft was airworthy with valid crew licenses. At the time of collision, the aircraft was correctly positioned on the taxiway centerline. The parking position A-48 features both inner (broken) and outer (solid) red marking lines, indicating clearance limits for narrow-body and wide-body aircraft respectively. The cleaning truck was erroneously parked inside the outer red line, which marks the boundary for aircraft types such as the Boeing 747. The truck driver, who was under training, and the supervising passenger stated they were unaware of the specific parking position assigned to the aircraft. The ground handling personnel present during the taxi did not give any warning signal to the crew.
Probable Cause
The incident is due to a continuation of the taxiing despite doubt about sufficient distance to an obstacle and despite a crew member's call to stop.