Narrative:

Flight XXX from ZZZ to atl on may/xa/98. We were dispatched with the APU inoperative, which means starting both engines at the gate. Prior to starting engines, I instructed the ground crew to leave external air and power hooked to the aircraft until after engine start. The aircraft was attached to a tug, and was chocked at block-in. I visually saw the tug and chocks (I stepped outside on the jetway to see what the day was like). I asked for the pushback/start checklist, the agent moved the jetway back, and the csc told me the 'cabin was ready for pushback.' we started #1 first. As we started #2, I noticed that #1 started to roll back slightly (N2 at 48-49%), and the egt started to rise, so I added throttle to stabilize the start in accordance with air carrier procedures. I was aware of the close proximity of personnel and equipment behind me, so I was careful adding power. When the #2 generator came on line, I told the tug driver the ground crew was cleared to disconnect external air and power. As #2 came on line, it did the same thing as #1: N2 at 48% and egt rising. I again added power to stabilize the start. At the time that #2 was stabilizing, the first officer stated it seemed to him that the jetway was moving. I was head down on the engine instruments and looked up. As I looked up, the first officer stated that there was no one in the tug and I instantly grabbed the brakes. The aircraft and tug had started to move forward. We stopped instantly with less of a jolt than most pushbacks. Immediately, the ground personnel came running, jumped into the now stopped tug, and looked to move levers, switches. The aircraft moved 3-5 ft. I asked the ground crew if anyone was hurt. The answer was no. I asked if the aircraft hit anything at all, the answer was again no. I asked are you sure, and the answer was still no. I asked the csc if everything was ok in the back, both for flight attendants and passenger. Her answer was everything was ok, the flight attendants did notice the stop, but everyone was fine. I decided that since all passenger, personnel, and equipment were ok, we would proceed. The flight to atl was uneventful. I will never (I hope) start the engines again without the brakes set.

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Original NASA ASRS Text

Title: AN MD88, AFTER PUSHBACK AND ENG START WITH THE TUG CONNECTED, ROLLED FORWARD. NO DAMAGE INCURRED.

Narrative: FLT XXX FROM ZZZ TO ATL ON MAY/XA/98. WE WERE DISPATCHED WITH THE APU INOP, WHICH MEANS STARTING BOTH ENGS AT THE GATE. PRIOR TO STARTING ENGS, I INSTRUCTED THE GND CREW TO LEAVE EXTERNAL AIR AND PWR HOOKED TO THE ACFT UNTIL AFTER ENG START. THE ACFT WAS ATTACHED TO A TUG, AND WAS CHOCKED AT BLOCK-IN. I VISUALLY SAW THE TUG AND CHOCKS (I STEPPED OUTSIDE ON THE JETWAY TO SEE WHAT THE DAY WAS LIKE). I ASKED FOR THE PUSHBACK/START CHKLIST, THE AGENT MOVED THE JETWAY BACK, AND THE CSC TOLD ME THE 'CABIN WAS READY FOR PUSHBACK.' WE STARTED #1 FIRST. AS WE STARTED #2, I NOTICED THAT #1 STARTED TO ROLL BACK SLIGHTLY (N2 AT 48-49%), AND THE EGT STARTED TO RISE, SO I ADDED THROTTLE TO STABILIZE THE START IN ACCORDANCE WITH ACR PROCS. I WAS AWARE OF THE CLOSE PROX OF PERSONNEL AND EQUIP BEHIND ME, SO I WAS CAREFUL ADDING PWR. WHEN THE #2 GENERATOR CAME ON LINE, I TOLD THE TUG DRIVER THE GND CREW WAS CLRED TO DISCONNECT EXTERNAL AIR AND PWR. AS #2 CAME ON LINE, IT DID THE SAME THING AS #1: N2 AT 48% AND EGT RISING. I AGAIN ADDED PWR TO STABILIZE THE START. AT THE TIME THAT #2 WAS STABILIZING, THE FO STATED IT SEEMED TO HIM THAT THE JETWAY WAS MOVING. I WAS HEAD DOWN ON THE ENG INSTS AND LOOKED UP. AS I LOOKED UP, THE FO STATED THAT THERE WAS NO ONE IN THE TUG AND I INSTANTLY GRABBED THE BRAKES. THE ACFT AND TUG HAD STARTED TO MOVE FORWARD. WE STOPPED INSTANTLY WITH LESS OF A JOLT THAN MOST PUSHBACKS. IMMEDIATELY, THE GND PERSONNEL CAME RUNNING, JUMPED INTO THE NOW STOPPED TUG, AND LOOKED TO MOVE LEVERS, SWITCHES. THE ACFT MOVED 3-5 FT. I ASKED THE GND CREW IF ANYONE WAS HURT. THE ANSWER WAS NO. I ASKED IF THE ACFT HIT ANYTHING AT ALL, THE ANSWER WAS AGAIN NO. I ASKED ARE YOU SURE, AND THE ANSWER WAS STILL NO. I ASKED THE CSC IF EVERYTHING WAS OK IN THE BACK, BOTH FOR FLT ATTENDANTS AND PAX. HER ANSWER WAS EVERYTHING WAS OK, THE FLT ATTENDANTS DID NOTICE THE STOP, BUT EVERYONE WAS FINE. I DECIDED THAT SINCE ALL PAX, PERSONNEL, AND EQUIP WERE OK, WE WOULD PROCEED. THE FLT TO ATL WAS UNEVENTFUL. I WILL NEVER (I HOPE) START THE ENGS AGAIN WITHOUT THE BRAKES SET.

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.