Boeing 787 N30913 incident near Chicago, Illinois

Probable cause

The flight crew’s misperception of the distance required to safely pass the hangar and failure to request additional ground handling support while taxiing, which resulted in a collision with a hangar. Contributing to the accident was United Airlines Maintenance Ramp personnel’s ambiguous taxi instructions and lack of obstruction clearance guidance.

NTSB analysis

United Airlines (UAL) flight 3885, a Boeing 787, impacted a hangar with its right-wing tip while taxiing to parking at Chicago O’Hare International Airport (KORD), Chicago, Illinois. The flight was a maintenance ferry flight conducted under Title 14 Code of Federal Regulations Part 91 from Newark Liberty International Airport (KEWR), Newark, New Jersey.

According to the flight crew, after landing on runway 10C at ORD they were cleared to taxi to a UAL maintenance facility via taxiways P to Z. After receiving an air traffic control (ATC) clearance, they crossed runway 10L, continued via taxiway Z crossing both runways 9R and 9C before making a right turn onto taxiway D. Ground control cleared them to enter the ramp at taxiway YY1 and to contact UAL’s Maintenance Ramp frequency. UAL maintenance subsequently instructed them to make a left on YY, which was incorrect, and proceed to the north side of the ramp, where a truck with marshallers would be waiting to guide them to parking. After completing the left turn on YY, the flight crew realized they were about to enter an American Eagle ramp area instead of their intended destination of the UAL ramp area.

Unfamiliar with the area they stopped the airplane and queried UAL maintenance as to where they should park. UAL maintenance asked the flight crew to proceed onto the American Eagle ramp and make a 180° turn. The captain noted no wingspan restrictions on the airport charts and no obstacles other than hangars in the area. He stated that there were no taxiway lights; however, there was adequate overhead lighting on the ramp.

The captain then asked the first officer (FO) if they were clear to the right, to which the FO responded “yes”. Shortly thereafter, while proceeding onto the ramp and on the associated taxiway line they heard a loud bang and the airplane veered to the right. The FO looked out his window and stated, “we hit the hangar”.

UAL Maintenance Ramp Area

Figure 1 - Google Earth image with taxi route in red. The inset photo of accident site was provided by United Airlines. Green arrow indicates the location of United Airlines maintenance ramp area.

The right-wing tip of the airplane struck a hanger resulting in minor damage to the wing. The damage to the hanger was estimated at about $236,000. A B787 has a wingspan of 197 feet 3 inches. The distance from the taxiway centerline to the hangar was about 98 ft accommodating a wingspan of about 196 ft.

Had the marshallers met the airplane at American Eagle ramp and provided obstruction clearance guidance and/or the flight crew requested additional ground handling support before attempting to turn around in an unfamiliar area it is likely that the collision would not have occurred.

Text from the NTSB. Open the NTSB docket for DCA24LA043 for the full record.