EMB-175 flight crew reported loss of aircraft control during pushback procedure.
Synopsis
EMB-175 flight crew reported loss of aircraft control during pushback procedure.
Narrative
As we prepared to push back; we established communication with the ground crew through the headset. Up until the event; we had no issues with the headset and clearly heard the tug driver. As we pushed off of the gate; there were no distractions and both pilots were silent and focused on the pushback. The tug driver told us we are clear to start engine one. Nothing was heard by either pilot after starting the engine. The wing walkers were standing in their normal positions and held up an 'X' with their marshal sticks. The aircraft started rolling forward and seemed as if the tug was pulling us forward. The aircraft was actually rolling freely towards the tug driver and the wing walkers ahead. The captain tried asking the tug driver if they need the brake set. I looked out of the window on my side; and saw the tug disconnected from the aircraft; at an angle; and reversing away from the aircraft. Shortly after seeing this; the tug driver says over the headset; 'Breakaway! Breakaway!' The captain quickly stepped on the brakes and set the parking brake/emergency brake. No indication was given; either with hand signals; or through the headset; to set the parking brake. The tug driver also confirmed over the headset that there is no damage. The ground crew was never told by the captain that they are cleared to disconnect from the aircraft. The captain told the ground crew that we never heard them tell us to set the brake; and the tug driver replied; and said there might have been an issue with the bluetooth headset. After the captain confirmed nobody was hurt and no damage to the aircraft occurred; he stated the parking brake is now set and cleared them to disconnect tow bar and headset.Suggestions: Reiterate to ground crews to not disconnect from the aircraft until they have confirmed the brake is set; and are told they are cleared to disconnect. If headset communication becomes an issue; automatically switch to hand signals.
Second reporter narrative
During Pushback and start up; the ZZZ ramp crew established communications with the flight deck prior to pushback. Once checklists were completed in the flight deck both pilots and ramp crew confirmed ready status to commence pushback including brakes released and steering off. FO Person B called ramp for push and the pushback began as normal. Comms were continued through the push and engine start. After push completion there was silence on the comms between ramp and flight deck. The aircraft began moving forward under its own power unknown to the flight deck crew. I queried the ramp if we needed to set brakes. There was no initial reply and the next communication the flight deck crew heard was the ramp crew calling break away several times. At this point I applied brakes and then set the parking/emergency brake. The ramp crew stated there was no damage observed to the aircraft or ground equipment. I asked if there were any injuries and the reply was no injuries. We double checked the ramp inspected the landing gear and that there was no damage to the aircraft. Several times during this time the ramp asked if they were clear to disconnect. With the brakes set and conditions met for disconnect we then cleared the ramp crew to disconnect. The tug driver stated as well during this time that he had stated set brakes to us and must have had a failure in his headset; since neither the first officer or myself had heard the command on the comms. At no point during the push back was there any indication of a failure in the towbar connections. This leads to the possibility the ramp crew disconnected the towbar without clearance from the flight deck. Suggestions: Reiterate to ground crew during training to not disconnect from the airplane without having approval from the flight deck crew especially if there is a perceived or actual comms failure between flight deck and ramp. Emphasize the need for proper hand signals throughout all phases of pushback whether comms are established or have failed.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.