Narrative:

I was driving an electric pushback tractor to assist in the dispatch of the flight. I followed normal SOP (test the brakes of the vehicle) and it seemed fine. As I got within 5 ft of the towbar I tried bringing the push back [tractor] closer to the tow bar. In doing so the pushback kept rolling towards the towbar when I eventually tried to stop it with the foot brakes. I attempted the hand brake but to no avail. At this time it had hit the connected towbar with the front already rolling over the towbar. By this time I already tried the two brakes and the emergency switch. But one of the pushback front wheels was already on top of the tow bar when it rolled over and to avert hitting the nose gear I steered it away from the plane and then finally was able to bring it to a complete stop by pulling the lever into park. I then called the lead who call the supervisor and the managers. I think because I didn't panic in such an event or I would have hit the aircraft head on. After realizing I had no control in stopping the push back; [I] steered it away from the aircraft; trying to avoid any further damages. I think those electric tractors are not suitable for pushback operations since they are not always reliable in stopping.

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Original NASA ASRS Text

Title: Ramp Agent reported an electric pushback tractor's brakes failed as he approached the towbar. The tractor ran over the towbar; but the driver steered away from the aircraft then stopped by pulling the lever into park.

Narrative: I was driving an electric pushback tractor to assist in the dispatch of the flight. I followed normal SOP (test the brakes of the vehicle) and it seemed fine. As I got within 5 ft of the towbar I tried bringing the push back [tractor] closer to the tow bar. In doing so the pushback kept rolling towards the towbar when I eventually tried to stop it with the foot brakes. I attempted the hand brake but to no avail. At this time it had hit the connected towbar with the front already rolling over the towbar. By this time I already tried the two brakes and the emergency switch. But one of the pushback front wheels was already on top of the tow bar when it rolled over and to avert hitting the nose gear I steered it away from the plane and then finally was able to bring it to a complete stop by pulling the lever into park. I then called the lead who call the supervisor and the managers. I think because I didn't panic in such an event or I would have hit the aircraft head on. After realizing I had no control in stopping the push back; [I] steered it away from the aircraft; trying to avoid any further damages. I think those electric tractors are not suitable for pushback operations since they are not always reliable in stopping.

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.