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Failure to follow procedures factor in collision between de-icing truck and Boeing 737-800
31 January 2016


Failure to follow procedures by the driver of a de-icing vehicle was a major factor in a taxiway collision with a Boeing 737-800 at Stavanger, Norway, according to an investigation.

On November 24, 2014, SAS flight SK4009, a Boeing 737-800, had landed at Stavanger Airport, Norway and was cleared by the ground air traffic controller to taxi towards the terminal via taxiway P.
Half a minute after the clearance was given, a driver started to move a SAS de-icing truck from the de-icing apron, crossed the red safety line and moved onto taxiway P without requesting compulsory clearance. Another half a minute later, the driver called the ground air traffic controller and informed that he was at the de-icing stand and requested clearance for crossing taxiway L and then further to the terminal. The ground air traffic controller asked him to keep clear, but after a SAS-aircraft had passed, he was cleared to drive towards the terminal.
When the flight 4009 approached taxiway P, both pilots saw a de-icing truck standing out on the left hand side and just outside the double yellow taxiway edge line. The commander commented to his first officer that the truck stood close, but ‘at least outside’. The commander considered that the truck was at safe distance, but chose to turn the aircraft a couple of meters to the right side of the center line on the taxiway to be extra safe. Shortly after the aircraft collided with the truck. There were no injuries, but the de-icing truck and the 1.6 meters outer part of the aircraft wing tip was severely damaged.
After the collision, the crew informed the ground air traffic controller that the aircraft had hit the deicing truck. No immediate crash alarm was activated and the commander continued to taxi towards the terminal.

Significant investigation results with significance for aviation safety:
a) Avinor had insufficient controls to ensure that traffic regulations were complied with. Inappropriate practices were not detected or corrected. This contributed to the accident.
b) The driver of deicing vehicle crossed the red safety line into the maneuvering area without obtaining clearance from the air traffic controller. This meant that the vehicle came into conflict with LN-RRS. The crossing of the security line was part of an unfortunate practice that had taken place over time, and also in violation of traffic regulations.
c) The driver of the deicing vehicle did not specify that he had run out on taxiway “P” when he called the tower and requested clearance to cross taxiway “L”. The ATCO assumed that the vehicle was parked behind the security line. This contributed to an air traffic controller not detecting the conflict between the deicing vehicle and the SAS aircraft.
d) The commander of LN-RRS assumed incorrectly that it was a safe distance when the vehicle was parked on the edge of taxiway “P”. The first officer dit not challenge the commander’s decision to continue taxiing past the deicing vehicle.
e) LN-RRS was not equipped with a wingtip camera that could have been an anti-collision aid to avoid collision on the ground. Such a system is not statutory but NTSB and AAIU has promoted safety recommendations in this area.

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