Incident Summary
During pre-flight preparations, a flight attendant was seriously injured after being ejected from an aircraft when a service door opened. The incident occurred while the cabin was pressurized by an external diesel-powered air conditioning cart, which was in use because the auxiliary power unit was inoperative.
Sequence of Events
The captain briefed the flight attendant twice—once before boarding and again in the cockpit—to keep one door open. However, the captain did not explain that the reason for this instruction was that the air conditioning cart could pressurize the cabin if all doors were closed.
After passenger boarding was completed, the flight attendant approached the cockpit. The captain asked her to close both the main cabin door and the service door. She closed the service door first, then crossed the galley and closed the main cabin door. Immediately after, the captain felt pressure rise in his ears and shouted, "GET THE DOOR OPEN."
The flight attendant went to the service door, bent down, held the assist handle with her left hand, and opened the door with her right hand. As the service door unlatched, it forcefully opened, ejecting the flight attendant onto the ground.
Training and Warnings
While flight crewmembers and ramp operators receive training on the operation and warnings about cabin pressurization when the air conditioning cart is connected, flight attendants do not receive any such training. The aircraft has two placards warning to keep a door open when the air conditioning cart is hooked up: one on the overhead console in the cockpit and another on the fuselage skin directly above the connection for the external air conditioning cart.