AN MD SUPER 80 AFTER PUSHBACK AND DURING ENG START THE GND CREW DISCONNECTED THE TOW BAR WITHOUT ADVISING THE CREW CAUSING THE ACFT TO ROLL FORWARD.

Narrative

WHILE WAITING FOR FINAL BAGS TO BE LOADED AT ZZZ; A TSTM BLEW IN AND THE RAMP WAS SHUT DOWN. ALL 3 CARGO COMPARTMENT DOORS WERE LEFT OPEN. THE RAIN WAS BLOWING HORIZLY INTO ALL CARGO COMPARTMENTS. I CALLED RAMP TO CLOSE THE DOORS AND THEY ADVISED THAT THEY COULD NOT BECAUSE OF RAMP CLOSURE. WHEN LOADING RESUMED; I TALKED TO THE CREW CHIEF WHO ADVISED THAT THERE WAS A LITTLE WATER IN THE CARGO COMPARTMENTS AND HE WOULD CLEAN IT UP. WE THEN PUSHED OFF THE GATE AND STARTED ENGS. AT THE END OF THE PUSH AS THE R ENG WAS COMING UP TO SPD; I PARKED THE BRAKES AND NOTICED THAT THE ACFT WAS TOTALLY WITHOUT ELECTRICAL PWR; EVEN THOUGH ALL 3 GENERATORS WERE PRODUCING PWR. I ADVISED ON INTERPHONE; BRAKES PARKED AND TO STAND BY. I COULD NOT GET ANY SYS ON LINE; SO I WENT TO EMER PWR. I REALIZED THAT WE HAD TO GET BACK TO THE GATE BECAUSE WE HAD NO AIR CONDITIONING AND NO ELECTRICAL PWR. WHAT I DID NOT KNOW IS THAT THE PUSH CREW HAD TAKEN IT UPON THEMSELVES TO DISCONNECT THE TOW BAR. I TOLD THE TUG DRIVER THAT WE HAD TO GET BACK TO THE GATE AND SHE SAID THAT SHE WOULD TOW ME BACK. I RELEASED THE BRAKES AND SIMULTANEOUSLY SAID BRAKES RELEASED. THE ACFT ROLLED FORWARD AND I SLAMMED ON THE BRAKES. I NEVER ADVISED CLRED TO DISCONNECT. NOBODY GOT HURT BUT IT WAS A VERY CLOSE CALL. THE ELECTRICAL SYS WAS POSSIBLY AFFECTED BY THE CARGO DOORS BEING LEFT OPEN IN THE RAIN.