Air carrier flight crew reported the aircraft rolled into the tug after push back following a failure of ground personnel to properly communicate with the flight crew.
Synopsis
Air carrier flight crew reported the aircraft rolled into the tug after push back following a failure of ground personnel to properly communicate with the flight crew.
Narrative
Prior to push we established communication with the ground crew and released the parking break per AOM procedures. The ground crew advised that there was another company aircraft pushed off a gate behind us and asked if we had 'a lot of checklists to do' after push. We stated that we didn't but since the other aircraft was ready; they could park us anywhere out of the way so the other aircraft could taxi out. The ground crew stated it was fine and they would put us in front of the other aircraft. We continued pushing off the gate in ZZZ. All was normal during the initial phase of the push - we were cleared to start engine 1 and did so. Shortly after engine start; the aircraft came to a stop. There was no communication from the ground crew at this point in time. I didn't think twice about the aircraft stopping as we were stopped on an angle; not on the taxi line still somewhat close to the gate. I thought the ground crew was going to pull us forward and straighten us out as there was another aircraft directly behind us. The next thing we heard was loud screaming in our headsets and heavy vibrations coming from the front of the aircraft. At this point I applied the breaks and immediately asked what was happening. The ground crew advised that the aircraft rolled forward into the tug. I stated that they never asked me to set the parking breaking nor did I state 'break set clear to disconnect the inter phone'. The ground crew then admitted that he 'screwed up' and didn't ask us to set the break. He also stated 'this is on me'. I immediately called Maintenance Control and informed them of the situation.Cause: This occurred due to a lack of the required communication from the ground crew to the flight crew that the pushback was complete and to set the parking brake. Had ground crew communicated with us prior to releasing the tug; this would not have occurred.Suggestions: Proper procedures from ground personnel should be adhered to.
Second reporter narrative
Prior to push from the gate at ZZZ airport; communication with the ground crew was established and Captain released the parking break per FOM and AOM pushback and engine start procedures. The ground crew advised that another company aircraft pushed off a gate behind us and asked if we had 'a lot of checklists to run?' after push to not hold up that flight. We informed them that we completed our applicable checklists but didn't want to hold up the other flight so they could park us in a position where the other aircraft could taxi out via Taxiway 1 or 2; I then coordinated with ZZZ Ground and the other aircraft. Ground; other aircraft crew and rampers all agreed there was no issue so they would put us in front of the other aircraft; we continued with the push. During the push; we were cleared by the ramp crew to 'Start Engine 1.' Shortly into the push and after engine start; the aircraft came to a stop. We were pushed at an angle and still fairly close to the gate; so I assumed it was a temporary pause in the push process and there was no communication from the ground crew at this point in time. The Captain and I both were under the assumption that the ramp crew was going to pull us forward onto the taxi line. We then felt a strong vibration along with screaming 'stop; stop; stop.' Both the Captain and I asked what happened/what was wrong…I thought someone got injured on the ground. The Captain immediately applied the toe brakes. The ground crew advised that the aircraft rolled forward and struck the tug. The Captain and I both stated that the ramp crew never informed the Captain to set the parking brake nor did the Captain ever state 'brakes set; cleared to disconnect interphone.' The ramper that pushed us admitted that 'he screwed up' and didn't state to set the brake; he also stated 'this is on me.' The other ramp crew admitted his mistake as well and said there was no way to hide this. Captain made the applicable notifications and we were towed back to the gate.Cause: Ramp crew did not utilize proper communication and verify the red light on the nose gear was illuminated ensuring the aircraft parking brake was set prior to disconnecting the tug.Suggestions: More thorough CRM to include further verification between ramp crew and flight crew was needed.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.