NTSB Factual Report

On December 16, 2007, about 1855 central standard time, a Bombardier CL-600-2B19 airplane, N918SW, operated by Skywest Airlines as flight 6034, was substantially damaged when the right wing struck a tug while taxing to the gate after landing at O'Hare International Airport (ORD), Chicago, Illinois. The domestic scheduled passenger flight was conducted under 14 CFR part 121 on an instrument flight rules flight plan. Night visual meteorological conditions prevailed at the time of the accident. The 29 passengers, 1 cabin crew member and 2 flight crew members were not injured. The driver of the tug was seriously injured. The flight departed Dane County Regional Airport (MSN), Madison, Wisconsin, about 1800. The intended destination was ORD.

The captain reported that the flight landed on runway 22R and was taxiing eastbound on taxiway B en route to gate F6. Between intersecting taxiways A9 and A10, the airplane hit something. The captain brought the airplane to a stop, but at the time the flight crew could not see what they hit. He subsequently continued and turned left onto taxiway A10. At that time he saw the overturned tug along the south edge of taxiway B at the service road intersection. He taxied to the assigned gate and deplaned the passengers without further incident. A post flight inspection by the first officer revealed impact damage to the leading edge of the right wing, within 4 feet of the wing tip. The damage extended aft to the forward wing spar.

The tug was operated by Continental Airlines. The driver was hospitalized for injuries received during the accident. At the time of this report, he had no recollection of the events surrounding the accident.

A witness reported that he was driving on the service road when he realized that an airplane was going to pass by on the taxiway. He stopped his van to allow the airplane to pass. He stated that the tug driver may have realized that the airplane was coming at the last minute and tried to slam on the brakes. However, the tug continued to slide forward and the right wing of the airplane hit the left side of the tug, flipping it over.

A pilot riding in the same van as the previous witness reported that they were following the tug on the service road and had stopped at taxiway B to allow the airplane to pass. He stated that when he looked up a second later, the airplane was passing in front of his van and he noticed that the tug was still moving slowly. He reported that as the airplane's wing passed the service road it struck the tug and knocked it over.

Two individuals that arrived on-scene after the accident recalled that the taxiway was wet at the service road intersection, but it was not snowing at that time. One of them commented that the airport terminal lights were reflected by the wet pavement. They also noted that it was a dark, "dreary" night.

The ORD weather observation taken at 1851 noted that winds were from 280 degrees at 9 knots, gusting to 18 knots, with 10 miles visibility. No precipitation or restriction to visibility was indicated.

The O'Hare Airport Ground Motor Vehicle Operation Regulations Manual stated that, "All ground vehicle operators must yield the right-of-way to an aircraft in motion." In addition, the manual required, "No person operating a ground vehicle will cross a Taxiway without bringing the vehicle to a complete stop."

NTSB Probable Cause

The tug driver's failure to yield the right-of-way to the airplane prior to crossing the active taxiway as required by airport procedures, and his subsequent failure to maintain clearance with the airplane. A contributing factor was the presence of the tug on the taxiway at the time the airplane passed the service road intersection. Additional factors were the wet pavement and the night lighting conditions.