Description

On 18 January 2003, a Boeing 747-400F being operated by Singapore Airlines Cargo on a scheduled cargo flight from Paris CDG to Dubai taxied for departure in darkness and fog with visibility less than 100 metres in places and the right wing was in collision with a stationary and unoccupied ground de/anti icing vehicle without the awareness of either the flight crew or anybody else at the time. Significant damage occurred to the de icing vehicle and the aircraft was slightly damaged. The vehicle damage was not discovered until almost two hours later and the aircraft involved was not identified until it arrived in Dubai where the damage was observed and the authorities at Paris CDG advised.

Investigation

An investigation was carried out by the French BEA. It was established that aircraft damage had been to the outer right wing slat and leading edge. Some small pieces of related debris were found at the site of the collision and a part of the slat was found on the northern edge of the take off runway 26. The operator’s control cabin on the de-icing vehicle was substantially damaged.

The Investigation noted as follows:

“The documentation on the parking of de-icing vehicles is imprecise. The dissymmetry of some zones is not indicated, nor is the function of the ground markings in relation to the positioning of the vehicles. On the contrary, the schematic diagrams for positioning the de-icing vehicles in operation may lead to the conclusion that positioning the vehicle onto the painted line does not create any risk; an agent’s experience would confirm this in fact, unless he had the opportunity to work on one of the rare zones where this supposition is incorrect.

The de-icing agent, who had never worked at (the incident location), did not know its specific characteristics, despite having visited it on foot during his training, and the bad visibility prevented him from noticing that he was placing his vehicle too near to the aircraft taxiing path. He did not pay any particular attention to the ground markings, probably routinely.

At the time the vehicles were put in place, the zones were not exactly activated, but « open ». This intermediate status, which leads to leaving the vehicles in place for a prolonged period with no driver, is not defined in the operations documentation and there is thus no precise corresponding procedure. This probably constitutes procedural drift.

The absence of any instructions relating to waiting time situations thus allowed the de-icing agent to leave the control cabin in the high position, a position usually reserved for de-icing operations, and to leave his vehicle without any other lighting than the position light. As there was no check procedure, either by the supervisor or by cross-checking, there was no chance that the incorrect positioning of the vehicle would be noticed and corrected as long as the visibility did not improve.

Once again, the BEA is led to note the lack of consistency between the level of requirements relating to airplane operations and the level of those that are applied in the immediate environment of the airplane on the ground.”

The Investigation Findings included that:

• The de-icing vehicle was positioned incorrectly with its telescopic boom retracted but the control cabin in the high position.
• The position of vehicles is not defined precisely in the documentation
• There was no procedure for checking the positioning of vehicles.
• The impact caused some damage to the aircraft wing but this damage did not have any actual consequences for the safety of the flight.

The Investigation determined that the Causes of the accident were as follows

• the incorrect positioning of a de-icing vehicle left without its driver

• the crew’s incorrect perception of the dimensions of the obstacle in a difficult environment in terms of lighting

Contributory Factors were identified as:

• the positioning of the control cabin in the high position

• the fact that the de-icing vehicle’s flashing light was not at the highest point on the vehicle, whereas the crew thought this to be the case, leading the pilots to estimate that the wing would not collide with the obstacle

• the likely procedural drift represented by the undefined procedure for pre-positioning the de-icing vehicles

• incomplete and imprecise documentation on the de-icing zones

• the absence of checks on the positioning of vehicles in the procedures for setting up the de-icing areas

The Final Report may be seen in full at SKYbrary bookshelf: BEA Report 9v-h030118a

No Safety Recommendations were made

Further Reading

• Ground Accident Prevention Program
• Wing Tip Clearance Hazard
• Vehicle Driver Airside Safety Check List
• Taxiway Surface Markings and Signs