Narrative:

We were pushing back from gate at dtw. The APU was on MEL status, therefore both engines were started at the gate using external air source. It was a normal pushback, perhaps a little slow, with poor outside visual reference and using abnormal procedures once we had no APU. During pushback there was a lot of external noise feeding through the intercom which made communications between the tug driver and the captain somewhat difficult. As I completed my normal flows and was ready for the captain to call for the before taxi check, the aircraft impacted the tug causing damage to the radome. At some point during the course of the pushback, we had a breakdown in communications whereas the tow bar was disconnected without the brakes being set. Contributing factors: APU not being available. It required the use of abnormal procedures. Late night operation. Perhaps being a little tired might have contributed in the chain of events. Communications: poor audio quality on the DC9 intercom between flight deck and ground crew. As a first officer I have my ear piece disconnected during ground operations to prevent serious damage to my ear drum. Also since engines were already on line, the feedback coming through the intercom made it difficult for the captain to understand what the mechanic was saying. Position of the tug 90 degrees relative to the aircraft: it seemed as if the pushback had not been completed, therefore it appeared as if the tug was still moving, but to our surprise the tow bar had been disconnected. Possible corrective solutions: always fly with an APU. Exercise extreme vigilance and caution -- especially during routine ground operations such as a pushback.

Google
 

Original NASA ASRS Text

Title: A DC9 ON PUSHBACK HITS TUG WHEN THE TOW BAR IS DISCONNECTED WITHOUT THE FLC'S KNOWLEDGE.

Narrative: WE WERE PUSHING BACK FROM GATE AT DTW. THE APU WAS ON MEL STATUS, THEREFORE BOTH ENGS WERE STARTED AT THE GATE USING EXTERNAL AIR SOURCE. IT WAS A NORMAL PUSHBACK, PERHAPS A LITTLE SLOW, WITH POOR OUTSIDE VISUAL REF AND USING ABNORMAL PROCS ONCE WE HAD NO APU. DURING PUSHBACK THERE WAS A LOT OF EXTERNAL NOISE FEEDING THROUGH THE INTERCOM WHICH MADE COMS BTWN THE TUG DRIVER AND THE CAPT SOMEWHAT DIFFICULT. AS I COMPLETED MY NORMAL FLOWS AND WAS READY FOR THE CAPT TO CALL FOR THE BEFORE TAXI CHK, THE ACFT IMPACTED THE TUG CAUSING DAMAGE TO THE RADOME. AT SOME POINT DURING THE COURSE OF THE PUSHBACK, WE HAD A BREAKDOWN IN COMS WHEREAS THE TOW BAR WAS DISCONNECTED WITHOUT THE BRAKES BEING SET. CONTRIBUTING FACTORS: APU NOT BEING AVAILABLE. IT REQUIRED THE USE OF ABNORMAL PROCS. LATE NIGHT OP. PERHAPS BEING A LITTLE TIRED MIGHT HAVE CONTRIBUTED IN THE CHAIN OF EVENTS. COMS: POOR AUDIO QUALITY ON THE DC9 INTERCOM BTWN FLT DECK AND GND CREW. AS A FO I HAVE MY EAR PIECE DISCONNECTED DURING GND OPS TO PREVENT SERIOUS DAMAGE TO MY EAR DRUM. ALSO SINCE ENGS WERE ALREADY ON LINE, THE FEEDBACK COMING THROUGH THE INTERCOM MADE IT DIFFICULT FOR THE CAPT TO UNDERSTAND WHAT THE MECH WAS SAYING. POS OF THE TUG 90 DEGS RELATIVE TO THE ACFT: IT SEEMED AS IF THE PUSHBACK HAD NOT BEEN COMPLETED, THEREFORE IT APPEARED AS IF THE TUG WAS STILL MOVING, BUT TO OUR SURPRISE THE TOW BAR HAD BEEN DISCONNECTED. POSSIBLE CORRECTIVE SOLUTIONS: ALWAYS FLY WITH AN APU. EXERCISE EXTREME VIGILANCE AND CAUTION -- ESPECIALLY DURING ROUTINE GND OPS SUCH AS A PUSHBACK.

Data retrieved from NASA's ASRS site as of July 2007 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.