Commercial Fixed Wing
Conflict Ground Conflict; Critical
Flight Crew Took Evasive Action
Human Factors
I was observing an inbound flight (widebody) at Gate XX. This gate is a tow in processed for widebody. While the aircraft was being marshalled in all of a sudden a cargo tractor appeared on the left side driving inside the OSZ [Operational Safety Zone] in a collision course of a number 2 engine. Thank god it never happened and he was able to able to avoid it. Once the plane was parked and secured. I did inquire and talked to wing-walker and the driver of the tractor to what transpired. Both had different stories. Wing-walker mentioned that he might be sleeping and got startled and drove off. Driver of tractor mentioned that wing-walker told him to move forward. Since both stories did not agree; I told them that we are very lucky and no one got hurt. Reminded them to have situational awareness at all times. Later that afternoon someone approach me and mention the near missed at gate. He mentioned that he tapped the rear window of the tractor to remind him that he was parked underneath the pathway of the aircraft wing tips. When all of sudden the tractor drove forward causing a near miss incident. Also; I've spoken to the marshaller if he saw the incursion of the tractor. He replied yes; but it was when the tractor was able to avoid the incident.
Ground employee reported observing a near ground collision between a cargo tractor and an aircraft under tow-in procedure.  Reportedly; communication issues between a wing-walker and the tractor driver contributed to the event.