What happened
On the evening of December 18, 2018, an Ethiopian Airlines Boeing 787-9 Dreamliner, registration ET-AUP, was taxiing through the "Bravo North" de-icing area at Oslo Airport Gardermoen. While following instructions to proceed to de-icing stand 991, the aircraft's right wing struck a light mast. The impact caused significant damage to the outer section of the aircraft's right wing, though no fuel leaks were reported. There were no injuries among the 59 passengers and 10 crew members on board.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined the sequence of events leading to the collision, focusing on the instructions provided by de-icing coordinators. The investigation found that the de-ing coordinators had verbally agreed to a specific traffic flow to accommodate large aircraft, which involved directing the ET-AUP to stand 991. However, this particular stand was only authorized for smaller Category C aircraft with wingspans up to 36 meters, whereas the Boeing 787 is a Category E aircraft with a much larger wingspan of approximately 60 meters.
The investigators also reviewed the technical environment at the de-icing platform. They noted a lack of physical indicators, such as signage, lights, or technical barriers, that would have alerted the flight crew to the fact that they were entering an area unsuitable for their aircraft type. Furthermore, the investigation looked into the visibility from the cockpit, noting that while the captain noticed the clearance seemed tight, the first officer was unable to visually confirm the distance between the wingtip and the mast.
Findings
Several contributing factors led to the collision:
- Incorrect stand allocation: De-icing coordinators assigned a stand intended for small aircraft to a wide-body jet.
- Lack of technical aids: The coordinators lacked sufficient technical tools to ensure correct stand allocation based on aircraft category, and SAS Ground Handling lacked specific work instructions for coordinators regarding aircraft categories until 2020.
- Inadequate visual warnings: There were no markings or barriers at the Bravo North area to signal that the assigned path was inappropriate for a Category E aircraft.
- Information gaps: The Aeronautical Information Publication and NOTAMs did not specify which stands at Gardermoen were authorized for this specific aircraft type.
- Limited cockpit visibility: The crew lacked an effective way to monitor wingtip clearance, such as a wingtip camera, which could have prevented the impact.