A Line Mechanic describes the chain of events that led to a company aircraft separating from a tow tug while being pushed back from a wash rack. Aircraft quickly moved forward and struck tug before Reporter could move tug out of the way.

Narrative

December 2011. My Wing Walkers were in position and the [flight deck] Brake Riding Crew called the Control Tower for clearance. Using hand signals; I got the 'brakes released' signal from the Brake Rider [in the cockpit]; so I got ready to push. So I had my headphones on and started to push at a steady and slow pace. I had angled the nose of the aircraft to my left slightly; so the tail could go left. The reason is because we had an Air Carrier Y's B737 directly behind us and next to it Air Carrier Z's B737 aircraft.Before passing the gate; I had noticed my aircraft had angled too much. While trying to straighten it out; my aircraft looks as if it were coming towards me. I had tapped on the brakes slightly to slow down but the aircraft kept getting closer and closer. So I stepped down all the way on the brakes; the aircraft is still moving towards me so I reacted quickly and decided to put it in forward and try to save the aircraft. At that time it was too late and the aircraft struck the push tug. The Wash Rack did have water on it so the pavement was slightly wet. I don't know why it happened; but I followed all the correct procedures in order to tow the aircraft. Suggest always stay in sight of Wing Walkers and in communication with Brake Riders. Stay at a steady and slow pace when towing; especially in wet conditions.