Incident Overview
Two maintenance technicians were onboard Northwest Airlines Airbus A319 (registration N313NB) as it was taxied from a maintenance area to Gate 10. Upon arriving in the vicinity of the gate, the mechanic steering the aircraft activated the parking brake and waited for ground personnel and a jetway operator. After ground personnel arrived, the parking brake was released.
Sequence of Events
The aircraft did not initially move, so the mechanic advanced the throttles out of their idle detents "a couple of inches, about halfway." The airplane then began to move at a "fairly decent speed." The mechanic realized the throttles were still out of the idle detent position and pulled them back while applying brakes. However, the aircraft did not slow and continued until it struck the concrete support column of the jetway. The left wing also contacted the right side of a Boeing 757-251 (registration N550NW), which was parked at Gate 9.
Damage
The nose gear of the Airbus A319 sheared off. The Boeing 757 sustained a 6-foot long, 2-foot wide gash just aft of the R1 door.
Flight Data Recorder Information
Initial review of the flight data recorder for the time period around the accident revealed that about 10 seconds after the parking brake was released, the thrust lever angles for both engines increased to about 17 degrees for about 8 seconds, before being returned to idle. During that time, engine N1 and N2 speeds increased to about 71% and 85%, respectively.
Additional Details
The mechanic estimated that the aircraft was about halfway down the parking line when he pulled back the throttles.