On October 24, 2002, at 2020 central daylight time, a Bombardier CL-600-2B19, N681BR, sustained substantial damage during a collision with a bus while taxiing for takeoff at the O'Hare International Airport (ORD), Chicago, Illinois. The 14 CFR Part 121 passenger flight was operated by Atlantic Coast Airlines as United Express Flight 7719, and was bound for the Portland International Jetport Airport, Portland, Maine. The pilot, first-officer, cabin attendant, and one passenger on-board the airplane received minor injuries. The remaining 48 passengers were not injured. The driver of the bus received minor injuries. Night visual meteorological conditions prevailed at the time of the accident. The airplane was taxiing to the northwest on taxiway B, between the taxiway A8 and A7 intersections, when a United Airlines employee shuttle bus struck it. The bus was traveling west-southwest on a service road when the collision occurred. The bus impacted the right side of the fuselage about 2 feet in front of the galley service door. The rear of the bus impacted the outboard leading edge of the right wing during the collision. An inquiry of ORD driver records showed that the driver of the bus held priveledges to operate ground vehicles on the airport. Those priveledges had been in effect since her hire date of March 15, 1999. The ORD Ground Vehicle Operating Regulations Manual states, in part: 9. C. Non-Movement Areas When it is not operationally practical to maintain two-way radio communications between the vehicle and the ATCT (Air traffic control tower) or to provide an escort vehicle, vehicles not equipped with two-way radios shall follow the procedures below: 1. Vehicle operators shall yield the right-of-way to all Aircraft at all times: ... 3. Vehicle Operators shall come to a complete stop where posted, prior to crossing any and all taxiways on the service roads. However, vehicles must avoid stopping in the islands between the A- (Alpha), B- (Bravo) and D- (Delta) taxiways. The crossing of these taxiways should not be initiated until the Operator ensures that both taxiways can be crossed in one continuous movement. Federal Aviation Administration Advisory Circular AC 150/521-20 paragraph 7 states in part: Some aspects of vehicle control and identification are discussed below; however, every airport presents different vehicle requirements and problems. Every airport will require individualized solutions to prevent vehicle or pedestrian traffic from endangering aircraft operations. It should be stressed that aircraft ALWAYS have the right-of-way over vehicles when maneuvering on non-movement areas. Aircraft also have the right-of-way on the movement areas, except when the Airport Traffic Control Tower (ATCT) has specifically instructed an aircraft to hold or give way to vehicle(s) on a runway or taxiway.