Pushback Maneuver
A Boeing 727 was pushed back from the gate in a counterclockwise arc of 90 degrees. This resulted in the aircraft being mispositioned relative to the intended taxi direction. The ground crew, including the tug and safety operators, attempted to correct the out-of-position condition by continuing the pushback through a second 90-degree counterclockwise arc. This second arc required pushing the aircraft upslope across the ramp.
Incident Sequence
During the second 90-degree arc, the tug became positioned approximately 90 degrees relative to the towbar and the aircraft's longitudinal axis. The combination of the downslope and idle power conditions overwhelmed the tug's braking capacity. As a result, the tow bar broke under a bending load. The aircraft then rolled forward and impacted the tug.
Engine Status
All three engines of the Boeing 727 were operating at idle thrust at the time of the incident.