Narrative:

Was ready for pushback. Captain released brake before engine was started; which is normally not a problem; but the parking brake on the tow tractor failed. Aircraft was immediately backing away and pulling the tow tractor. I repeatedly tried to apply brakes and start the engine. Neither was working; so I was just trying to keep the aircraft going straight so I didn't lose control of the steering. The captain at first was telling me I didn't have clearance to push. I was telling him I had lost brakes; but was also trying to keep the aircraft that was increasing in speed straight. My lead was signaling the cockpit to ease the brakes and the captain told me he knew not to just set the brakes or it would break the tow bar; I said yes; please stop the aircraft slowly or something to that effect. Once the aircraft reached the vsr (vehicle service road) and ran over the drainage grate; it began to turn tail left. With limited steering I was having to fight to keep the tow bar from going past the red line. It never got too close or past that point; but was heading in that direction when the captain eased the aircraft to a stop. My lead was able to move the shifter and get the tractor to start. As soon as the tractor was running and the brakes were working; I told the cockpit to release the brakes so I could straighten the aircraft out as it was pretty near where it needed to go and the ramp had just closed due to lightning. My lead was there with me and there was no damage to the tow bar/shear pin. If there was anything I could have done. It would have been to make sure the pushback was running before I talked to the flight deck. I have never had an incident before where the tractor (running or not) was unable to hold the aircraft.

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Original NASA ASRS Text

Title: Tow tractor driver reported the tow tractor brakes failed during push-back.

Narrative: Was ready for pushback. Captain released brake before engine was started; which is normally not a problem; but the parking brake on the tow tractor failed. Aircraft was immediately backing away and pulling the tow tractor. I repeatedly tried to apply brakes and start the engine. Neither was working; so I was just trying to keep the aircraft going straight so I didn't lose control of the steering. The Captain at first was telling me I didn't have clearance to push. I was telling him I had lost brakes; but was also trying to keep the aircraft that was increasing in speed straight. My lead was signaling the cockpit to ease the brakes and the Captain told me he knew not to just set the brakes or it would break the tow bar; I said yes; please stop the aircraft slowly or something to that effect. Once the aircraft reached the VSR (Vehicle Service Road) and ran over the drainage grate; it began to turn tail left. With limited steering I was having to fight to keep the tow bar from going past the red line. It never got too close or past that point; but was heading in that direction when the Captain eased the aircraft to a stop. My lead was able to move the shifter and get the tractor to start. As soon as the tractor was running and the brakes were working; I told the cockpit to release the brakes so I could straighten the aircraft out as it was pretty near where it needed to go and the Ramp had just closed due to lightning. My lead was there with me and there was no damage to the tow bar/shear pin. If there was anything I could have done. It would have been to make sure the pushback was running before I talked to the flight deck. I have never had an incident before where the tractor (running or not) was unable to hold the aircraft.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.