B737-700
Communication Breakdown; Training / Qualification
Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action
Company Policy; Procedure; Human Factors
On push back; while starting the #1 engine; the Ground Controller disconnected the tug and his headset prior to getting clearance from the Captain. This resulted in the brakes not being set and hence a movement of the airplane forward before we realized the situation and applied the brakes.
We were getting ready for pushback; the Ground Crew said that the walk around was complete and the bypass pin was in and that I was cleared to release brakes. After getting a cleared to push clearance from Ramp Control I told Ground Crew that his transmission was weak; but that the brakes were released and cleared for push. During the push the Ground Crew said something that I couldn't understand so I asked him to repeat which he did and although it was weak and had a lot of static noise I was able to make out that we were cleared to start engines. I started #2 engine and then he said something that was totally unreadable due to the static and noise and the First Officer and I asked each other if either of us understood what he had said which we did not. At that point I was starting the #1 engine and monitoring the start when I glanced up momentarily and felt as though we were moving forward and I made a comment questioning why they would be towing us forward; since I could see the tug going backward; it was at that point when the First Officer told me that we were not connected and that we were rolling forward and to set brakes. I set the brakes and the First Officer said he got a wave off from the ground crew with the bypass pin. The Marshaler on the left then gave me a cleared to go hand signal and wave off as they cleared and went back to the gate. I never received a 'set brakes' command nor did I give a' brakes are set cleared to disconnect go to hand signals'. Ground Crew disconnecting without verbal clearance to due so; compounded by poor ground crew communications.
A B737-700 crew reported that the ground crew disconnected the tow bar after pushback without any communications; which caused the aircraft to roll backward because the brakes were not set.