On January 8, 2002, at 0526 eastern standard time, a Swearingen SA-227-AT, N556UP, operated by Ameriflight, Inc., as flight 667, was struck by a tug while taxiing for departure at the Cincinnati/Northern Kentucky International Airport, Covington, Kentucky. The certificated airline transport pilot received minor injuries, and the tug driver was not injured. Visual meteorological conditions prevailed. An instrument flight rules flight plan had been filed for the cargo flight conducted under 14 CFR Part 135. The accident occurred at the west end of concourse A, between concourses A and B. The airplane was taxiing east in the open area between the concourses. The tug was southbound on a road between concourses A and B. The road crossed the taxipath of the airplane, and the ramp area was illuminated by flood lights. Yield signs were present where the roadway entered the ramp, and the roadway was defined by painted lines on the ramp. According to a written statement from the pilot: "...At a point a little short of halfway between spot 2C and 3, my airplane was hit from the left side by Delta tug towing a cart. I hit my forehead on the left side windshield which left a welt on my forehead." According to a written statement from the tug driver: "...I had 3 oversize bags to take out to B-18...As I passed A-Concourse to enter the mid-ramp, I checked both ways for traffic. I did not see aircraft or lights and proceeded across the taxi way in the designated drive lane, just west of A-Hub. It was very dark and as I was in the taxi-way, all of a sudden I noticed an aircraft right on top of me to the right side. I immediately swerved to the left but was unable to avoid a collision. The aircraft's left prop struck my bag cart and knocked the cart over. There was also damage to wing and nose of the aircraft and the passenger side window of my tug was broken...." According to a written statement from a witness: "...I was driving a tug and was in between gates A-1 and A-3. I witnessed a tug and cart being driven across the taxiway between A Concourse and heading toward B concourse. I then saw a small plane taxiing east, faster than a typical speed. the aircraft lights were on. I then watched as the tug and car and the airplane closed on each other. The plane hit the bag cart on the wing, then the bag cart tipped over and slammed against the driver door on the bag tug...." Interviews were conducted by the airport police. According to the statement from the investigating officer: "...[the pilot] stated that he was taxiing the aircraft eastbound on the north taxi land between A and B concourse. When he approaching the ramp road that runs north and south near the west side of A concourse he observed a tug crossing the ramp road. Once he realized that the tug was not going to stop he hit the brakes. He stated that he could not avoid the accident. [the tug driver]...stated that he was driving south on the ramp road. He stated that when he looked he did not see any aircraft on the taxi lanes. As he continued across the ramp he suddenly looked up and saw the aircraft but it was too late. He stated that he attempted to turn hard left but it was too late." In a follow-up telephone interview, the police officer reported that ramp-side driving rules give the right of way to airplanes, yield signs were present on the roadway where the roads entered the ramp area, the ramp was dry and no ice was present, and there were no obstructions to visibility for the tug driver or pilot. The pilot had been on duty for 9 hours at the time of the accident, following 12 hours off duty. He was on his second day of duty following 2 days off duty. The tug driver had been on duty for 26 minutes at the time of the accident, following 16 hours off duty. He was on his second day of duty following 2 days off duty.