Date: 201204
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Night
Aircraft: B767-300 and 300 ER
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: Nose Gear
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Powerplant; Maintenance Airframe
Human factors: Communication Breakdown; Confusion; Situational Awareness
Second reporter function: Technician
Anomaly: Ground Event / Encounter Other / Unknown
Detector: Person Maintenance
When detected: Other During Aircraft Tow
Result: General Maintenance Action
Contributing factors: Human Factors; Aircraft; Equipment / Tooling
Primary problem: Equipment / Tooling

Narrative: [I] was towing a B767-300 aircraft from Gate to the Maintenance Base. I hooked-up the towbar to the aircraft and proceeded to prepare the aircraft for pushback. After the jetway was pulled and [Ramp] envelope cleared; I contacted the Brake Rider to turn on hydraulics and release brakes while I contacted the Ramp Controller for clearance. After receiving push back clearance; I pushed back into the open area. Once my pushback was completed; I contacted Ramp Control again for clearance to proceed forward. I was given clearance to proceed up the north line to Spot X and contact Ground Control. Once I arrived at Spot X; I contacted Ground Control for clearance from Spot X to the east gate of our Maintenance Base. I was cleared to taxi to Alpha-1 and told to hold. Once I arrived to my hold area; Ground Control instructed me to wait for company aircraft to pass from right to left; then proceed via Alpha-1/Yankee and to hold short at Spot XA. While making my turn off of Alpha-1 onto Yankee; I heard a metallic rattle from behind me. I immediately looked over my shoulder to see what the problem was when I noticed I was separated from the aircraft. I than called [out] 'break-away' over my headset to the cockpit; but noticed that the communication's cord had already sheared. I then contacted Ground Control to notify them that I had a break-away from my towed aircraft and requested Airfield Safety assistance. I then contacted my Supervisor over the Maintenance frequency that I needed his presence at Taxiway Yankee and that an incident had occurred.


Second narrative: Ground Control cleared company Tug X (B767-300 aircraft under tow) from Alpha-1 to Yankee; to our Maintenance Base. As the aircraft transitioned from Alpha-1 to Yankee; I noticed the aircraft's nose was to the left of the taxiway's centerline green lights; at the intersection of Alpha-1 and Yankee. As the aircraft continued towards Yankee; the centerline lights remained to the right. I turned my sight to the left of the aircraft and saw the Taxiway Sierra marker sign passing the flight deck side window. Noticing it was way too close for the proper distance; I made a call to the Tug Driver to warn him we were way too [far to] the left. There was no response to the call. I also noticed there was an absence of the Tug's headlight's out of the [Flight deck's] windshield.After a second immediate call; with no response; I transmitted on the flight intercom (to the Tug Driver) that I am applying brakes. I applied the brakes and brought the aircraft to a complete stop. There was no noise in the flight deck that indicated the tow bar (and tug) had disconnected; along with the intercom communication cord. Prior to the aircraft's complete stop; I did hear rumbling sounds from the left side of the aircraft.


Synopsis: A Tug Driver and a Brake Rider in the flight deck of a B767-300 lost communications with each other after the tug and tow bar became disconnected.