Synopsis
On 11 October 2013, a Boeing 737-400 aircraft, registration TC-TLE, was involved in a serious incident at Zurich Airport. The aircraft left the paved surface and came to a stop on the adjacent soft ground.
Factual Information
The incident occurred during taxiing. The flight crew did not follow the green centreline lights, which led to the aircraft departing the hardstanding and stopping on soft terrain. The taxi instruction provided to the crew did not specify which de-icing road to use when crossing the de-icing area. Additionally, the de-icing roads were not equipped with taxiway edge lighting. The grass areas between the de-icing roads were difficult to discern at night and when the surface was wet, which facilitated the occurrence.
Causes
The serious incident was caused by the flight crew not following the green centreline lights. Contributing factors were: the taxi instruction lacked specification of the de-icing road to be used; the de-icing roads lacked taxiway edge lighting; and the grass areas between the de-icing roads were hard to see under conditions of darkness and wet surface.