Overview
During a ground handling operation, a Boeing 727 aircraft was chocked and awaiting a tug. A mechanic/ramp employee arrived with a tug and tow bar to move the aircraft.
Accident Sequence
After stopping the tug, the employee disconnected the tow bar from the tug and connected it to the nose gear of the aircraft. He then re-boarded the tug to maneuver it closer to the tow bar for attachment. However, instead of stopping, the tug continued moving forward. It contacted the tow bar, which slid off the face of the tug. The tug continued its forward motion and made contact with the underside of the aircraft's nose, crushing the employee between the tug and the airplane.
Investigation Findings
The tug driver was wearing a built-up shoe on his right foot. Subsequent tests revealed that with this shoe placed under the brake pedal, the braking action of the tug was insufficient to stop the vehicle. Scuff marks and signs of scraping were noted on the toe of the boot, but the source of these marks was not verified.
Probable Cause: Not specified in the source.