Narrative:

The pushback began in a normal fashion. Engine start was uneventful until the after start flows were accomplished. At that point we experienced a problem with the left bleed air valve. I told the mechanic we were probably going to need to be tugged back to our parking spot. He acknowledged this. Sure enough; the MEL showed this as a return to gate item. At this point; I told the mechanic we needed to be tugged back in. His response sounded like he was asking us to release the parking brake; however; neither of us quite understood what he had said about the brakes. I asked him if he was asking us to release the parking brake; to which he responded; 'release parking brake.' I released the parking brake and the tug operation commenced. With the tug operation underway; I turned my attention towards the logbook; thinking about how I was going to write up this problem. The first officer put away the QRH and then was looking over the MEL; which listed restrictions about flying in icing conditions. What to me seemed like a few seconds after we began to be tugged; the first officer rhetorically asked; 'where is this guy taking us?' as I looked up I saw the end of the paved ramp approaching rapidly and heard the first officer say something about stopping the aircraft. At that point we were both simultaneously on the brakes. It's strange what you notice during such times; but I somehow saw the ground speed on the eadi at 15 knots. After leaving about 20 feet of skid marks on the ramp; the aircraft came to a stop with the nosewheel approximately 8 feet from the end of the paved surface...and without the tug connected!! After stopping the aircraft and shutting down the engines and trying to comprehend what had just happened; my next concern was the location of the mechanic and if he was okay. He was okay. Although this mechanic speaks fairly good english; I was truly surprised at the level of communications breakdown that had just occurred. While still in the cockpit and leaning out the window; I asked him why he had told me to release the brakes. Quite shaken; he simply responded with; 'I don't know.' later; after things had calmed down; I spoke with him again and he told me he thought I was telling him I was releasing the parking brake. Once we started rolling he did not tell us to stop; but instead simply unplugged his headset and got out of the way. What lessons can be learned or relearned from all of this? First of all this is a reminder of something we all know; that being tugged is an operation which requires someone to be monitoring the aircraft. Secondly; never assume anything. Since we never saw the tug pull away (it pulled away while we were in the books); and we were told to release the parking brake; we thought we were under tow. The potential for such communication breakdowns will continue to increase as we service more and more international destinations. Also; next time I have determined I need to do a return to gate; I will shut down the engines sooner or just power in myself. We were so distracted by what was going on that neither of us thought of shutting down the engines; nor did it seem critical at the moment since we thought we were under tow. This was quite a set-up; wouldn't you say? Could it have happened to you? Is someone in your crew always assigned to monitor the aircraft during tow operations or does everyone start putting things away in their flight bags; collecting the international garbage; completing customs documentation; etc? During approach briefings; simulator training; and line non-normal operations in-flight; someone is always assigned the task of monitoring the aircraft. Let this serve as a reminder to do the same during tow operations. Thank goodness no one was hurt; no metal was bent; and no careers were put in jeopardy; but we sure came darn close.

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Original NASA ASRS Text

Title: COMMUNICATIONS BREAKDOWN BETWEEN COCKPIT AND TUG DRIVER RESULTS IN ACFT MOVEMENT WITH NO ONE IN POSITIVE CONTROL ON THE ACFT.

Narrative: THE PUSHBACK BEGAN IN A NORMAL FASHION. ENGINE START WAS UNEVENTFUL UNTIL THE AFTER START FLOWS WERE ACCOMPLISHED. AT THAT POINT WE EXPERIENCED A PROBLEM WITH THE LEFT BLEED AIR VALVE. I TOLD THE MECHANIC WE WERE PROBABLY GOING TO NEED TO BE TUGGED BACK TO OUR PARKING SPOT. HE ACKNOWLEDGED THIS. SURE ENOUGH; THE MEL SHOWED THIS AS A RETURN TO GATE ITEM. AT THIS POINT; I TOLD THE MECHANIC WE NEEDED TO BE TUGGED BACK IN. HIS RESPONSE SOUNDED LIKE HE WAS ASKING US TO RELEASE THE PARKING BRAKE; HOWEVER; NEITHER OF US QUITE UNDERSTOOD WHAT HE HAD SAID ABOUT THE BRAKES. I ASKED HIM IF HE WAS ASKING US TO RELEASE THE PARKING BRAKE; TO WHICH HE RESPONDED; 'RELEASE PARKING BRAKE.' I RELEASED THE PARKING BRAKE AND THE TUG OPERATION COMMENCED. WITH THE TUG OPERATION UNDERWAY; I TURNED MY ATTENTION TOWARDS THE LOGBOOK; THINKING ABOUT HOW I WAS GOING TO WRITE UP THIS PROBLEM. THE FIRST OFFICER PUT AWAY THE QRH AND THEN WAS LOOKING OVER THE MEL; WHICH LISTED RESTRICTIONS ABOUT FLYING IN ICING CONDITIONS. WHAT TO ME SEEMED LIKE A FEW SECONDS AFTER WE BEGAN TO BE TUGGED; THE FIRST OFFICER RHETORICALLY ASKED; 'WHERE IS THIS GUY TAKING US?' AS I LOOKED UP I SAW THE END OF THE PAVED RAMP APPROACHING RAPIDLY AND HEARD THE FIRST OFFICER SAY SOMETHING ABOUT STOPPING THE AIRCRAFT. AT THAT POINT WE WERE BOTH SIMULTANEOUSLY ON THE BRAKES. IT'S STRANGE WHAT YOU NOTICE DURING SUCH TIMES; BUT I SOMEHOW SAW THE GROUND SPEED ON THE EADI AT 15 KNOTS. AFTER LEAVING ABOUT 20 FEET OF SKID MARKS ON THE RAMP; THE AIRCRAFT CAME TO A STOP WITH THE NOSEWHEEL APPROXIMATELY 8 FEET FROM THE END OF THE PAVED SURFACE...AND WITHOUT THE TUG CONNECTED!! AFTER STOPPING THE AIRCRAFT AND SHUTTING DOWN THE ENGINES AND TRYING TO COMPREHEND WHAT HAD JUST HAPPENED; MY NEXT CONCERN WAS THE LOCATION OF THE MECHANIC AND IF HE WAS OKAY. HE WAS OKAY. ALTHOUGH THIS MECHANIC SPEAKS FAIRLY GOOD ENGLISH; I WAS TRULY SURPRISED AT THE LEVEL OF COMMUNICATIONS BREAKDOWN THAT HAD JUST OCCURRED. WHILE STILL IN THE COCKPIT AND LEANING OUT THE WINDOW; I ASKED HIM WHY HE HAD TOLD ME TO RELEASE THE BRAKES. QUITE SHAKEN; HE SIMPLY RESPONDED WITH; 'I DON'T KNOW.' LATER; AFTER THINGS HAD CALMED DOWN; I SPOKE WITH HIM AGAIN AND HE TOLD ME HE THOUGHT I WAS TELLING HIM I WAS RELEASING THE PARKING BRAKE. ONCE WE STARTED ROLLING HE DID NOT TELL US TO STOP; BUT INSTEAD SIMPLY UNPLUGGED HIS HEADSET AND GOT OUT OF THE WAY. WHAT LESSONS CAN BE LEARNED OR RELEARNED FROM ALL OF THIS? FIRST OF ALL THIS IS A REMINDER OF SOMETHING WE ALL KNOW; THAT BEING TUGGED IS AN OPERATION WHICH REQUIRES SOMEONE TO BE MONITORING THE AIRCRAFT. SECONDLY; NEVER ASSUME ANYTHING. SINCE WE NEVER SAW THE TUG PULL AWAY (IT PULLED AWAY WHILE WE WERE IN THE BOOKS); AND WE WERE TOLD TO RELEASE THE PARKING BRAKE; WE THOUGHT WE WERE UNDER TOW. THE POTENTIAL FOR SUCH COMMUNICATION BREAKDOWNS WILL CONTINUE TO INCREASE AS WE SERVICE MORE AND MORE INTERNATIONAL DESTINATIONS. ALSO; NEXT TIME I HAVE DETERMINED I NEED TO DO A RETURN TO GATE; I WILL SHUT DOWN THE ENGINES SOONER OR JUST POWER IN MYSELF. WE WERE SO DISTRACTED BY WHAT WAS GOING ON THAT NEITHER OF US THOUGHT OF SHUTTING DOWN THE ENGINES; NOR DID IT SEEM CRITICAL AT THE MOMENT SINCE WE THOUGHT WE WERE UNDER TOW. THIS WAS QUITE A SET-UP; WOULDN'T YOU SAY? COULD IT HAVE HAPPENED TO YOU? IS SOMEONE IN YOUR CREW ALWAYS ASSIGNED TO MONITOR THE AIRCRAFT DURING TOW OPERATIONS OR DOES EVERYONE START PUTTING THINGS AWAY IN THEIR FLIGHT BAGS; COLLECTING THE INTERNATIONAL GARBAGE; COMPLETING CUSTOMS DOCUMENTATION; ETC? DURING APPROACH BRIEFINGS; SIMULATOR TRAINING; AND LINE NON-NORMAL OPERATIONS INFLT; SOMEONE IS ALWAYS ASSIGNED THE TASK OF MONITORING THE AIRCRAFT. LET THIS SERVE AS A REMINDER TO DO THE SAME DURING TOW OPERATIONS. THANK GOODNESS NO ONE WAS HURT; NO METAL WAS BENT; AND NO CAREERS WERE PUT IN JEOPARDY; BUT WE SURE CAME DARN CLOSE.

Data retrieved from NASA's ASRS site as of January 2009 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.