NTSB Identification: WPR11LA300
Scheduled 14 CFR Part 121: Air Carrier operation of United Airlines
Accident occurred Tuesday, May 31, 2011 in Los Angeles, CA
Probable Cause Approval Date: 11/07/2012
Aircraft: BOEING 757-222, registration: N526UA
Injuries: 1 Serious,190 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The tug’s tow bar’s shear pins broke while the airplane was being pushed back from the gate to an adjacent alley (a “turn reversal”), which required a significant (but within limits) turn of the nose landing gear. The tow bar became stuck and, despite repeated attempts by the operator’s ground crew personnel, would not disconnect from the tug or the airplane. When the operator’s ground personnel asked the pilots to release the airplane’s parking brake to ease the tension on the tow bar, the pilots did so. The airplane rolled slightly forward, contacting and fracturing the foot of one of the ground crewmembers. Although the operator’s ground crew ramp service manual procedure and flight manual guidance specified that the airplane’s parking brakes should not be released to assist in releasing a stuck tow bar, the pilots stated that they released the brakes believing that they were going to resume pushback. As a result of a postaccident hazard assessment, the operator stopped performing turn reversal tow operations similar to the accident operation.

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

The ground crewmembers’ failure to follow proper procedures for removing a stuck or jammed tow bar, which resulted in a ground crew injury.

Full narrative available

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