Narrative:

Standard push back communications were completed and I told the guide person he was cleared to push. Late in the push the flight officer (first officer) asked me if I wanted to start an engine. I said; ground to cockpit can I start engine #1? Ramp to cockpit; cleared to start engine one. The first officer started the #1 engine. The tug came to a stop. Out of the corner of my eye I saw the wing walker in an orange vest holding the interphone cord approaching the airplane as if he was going to disconnect. There was also a ramper to the right approaching the nose. There had been no communication from the tug driver. I said to him; do you want me to set the brakes? There was no answer. I said again; wait; do you want me to set the brakes? There was no answer. I said; what's going on down there; is push back complete? We need to set brakes before you disconnect. Still no answer. The first officer then also announced on the interphone the need to set the parking brake. I looked to my left and saw that we weren't moving and told him I was setting my brakes. The tug then rolled forward until it struck the nose of the aircraft. Immediately prior to the tug impacting the aircraft we observed the tug driver attempt to turn the tug to his right. After impacting the aircraft the tug's power briefly vibrated the front of the aircraft. When communication was re-established we learned that they were rushing to find a tug to move the tug off the plane. Rampers were immediately moving about. I made several attempts to get into contact with someone on the ground. Flashed my lights and called on the operations frequency. When communications were re-established we learned that they were rushing to find a tug to move the tug off the plane. I told them not to touch the tug or the aircraft so as to not cause additional damage. I told them we needed to deplane via stairs and walk the passengers into the terminal. We contacted operations control through ACARS and made an aml entry. Called maintenance operations control shortly after. Communications failed between the ramp and the cockpit. The interphone and equipment should not be removed without clearance from the captain.follow procedures; when the first verbal command is not exchanged the process should be stopped until communications can resume.

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Original NASA ASRS Text

Title: When communication between the flight crew and pushback was lost for unexplained reasons the flight crew set the aircraft brakes but the tug kept moving and struck the nose of the aircraft. Passengers were evacuated on the ramp and walked to the terminal rather than attempt to tow aircraft back to the gate risking further damage.

Narrative: Standard push back communications were completed and I told the Guide person he was cleared to push. Late in the push the Flight Officer (FO) asked me if I wanted to start an engine. I said; ground to cockpit can I start Engine #1? Ramp to cockpit; cleared to start engine one. The FO started the #1 engine. The tug came to a stop. Out of the corner of my eye I saw the wing walker in an orange vest holding the interphone cord approaching the airplane as if he was going to disconnect. There was also a ramper to the right approaching the nose. There had been no communication from the tug driver. I said to him; do you want me to set the brakes? There was no answer. I said again; wait; do you want me to set the brakes? There was no answer. I said; what's going on down there; is push back complete? We need to set brakes before you disconnect. Still no answer. The FO then also announced on the interphone the need to set the parking brake. I looked to my left and saw that we weren't moving and told him I was setting my brakes. The tug then rolled forward until it struck the nose of the aircraft. Immediately prior to the tug impacting the aircraft we observed the tug driver attempt to turn the tug to his right. After impacting the aircraft the tug's power briefly vibrated the front of the aircraft. When communication was re-established we learned that they were rushing to find a tug to move the tug off the plane. Rampers were immediately moving about. I made several attempts to get into contact with someone on the ground. Flashed my lights and called on the operations frequency. When communications were re-established we learned that they were rushing to find a tug to move the tug off the plane. I told them not to touch the tug or the aircraft so as to not cause additional damage. I told them we needed to deplane via stairs and walk the passengers into the terminal. We contacted operations control through ACARS and made an AML entry. Called maintenance operations control shortly after. Communications failed between the ramp and the cockpit. The interphone and equipment should not be removed without clearance from the Captain.Follow procedures; when the first verbal command is not exchanged the process should be stopped until communications can resume.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.