NTSB Identification: DCA05MA071.
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Scheduled 14 CFR operation of Air Wisconsin Airlines Corporation (D.B.A. United Express)
Accident occurred Tuesday, May 31, 2005 in Chicago O'Hare, IL
Probable Cause Approval Date: 04/25/2007
Aircraft: Bombardier, Inc. CL-600-2B19, registration: N417AW
Injuries: 1 Serious,26 Uninjured.

NTSB investigators traveled in support of this investigation and used data obtained from various sources to prepare this aircraft accident report.

While the flight crew was preparing the aircraft for flight, the flight attendant opened the service door and was ejected onto the tarmac and seriously injured. At the time of the accident, the airplane was being cooled by an external diesel powered air conditioning cart that pressurizes the cabin when the airplane doors are closed. The external air conditioning cart was required because the auxiliary power unit was inoperative. The captain said that he briefed the flight attendant, before boarding the airplane and again in the cockpit, to keep one door open. The captain did not specify that the reason the flight attendant needed to keep a door open was because the air conditioning cart pressurized the cabin if all the doors were closed. After passenger boarding was completed the flight attendant stated she approached the cockpit and the captain asked her to close the main cabin door and the service door. She closed the service door, and crossed the galley and closed the main cabin door. Right afterward, the captain felt the pressure rise in his ears and yelled "GET THE DOOR OPEN." The flight attendant approached the service door and bent down, held the service door assist handle with her left hand and opened the service door with her right hand. As the service door unlatched it forcefully opened and ejected the flight attendant onto the ground. Although the flight crewmembers and ramp operators receive training regarding the operation and warnings of pressurizing the cabin when the air conditioning cart is hooked up to the airplane, the flight attendants do not receive any training on the operation and warnings for the external air conditioning cart. The airplane has two placards warning to keep a door open when the air conditioning cart is hooked up to the airplane. One placard is on the overhead console in the cockpit and the other is outside of the cabin on the fuselage skin directly above the connection for the external air conditioning cart.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The opening of the service door when the airplane was pressurized. Contributing to the accident was the captain's failure to ensure that one of the airplane doors was open while a ground-cooling cart was connected, which resulted in pressurizing the airplane on the ground.

Full narrative available

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