Narrative:

Taxied to stop at gate, set parking brake and shut down engines. Completed cockpit postflt shutdown procedures. Completed shutdown checklist and released parking brake. Aircraft did not move, but a short time later a scraping noise was heard behind instrument panel. Opened cockpit window and asked mechanic standing under jetway what was going on. He said 'you rolled forward.' I said 'I thought the chocks were in,' and he said 'they are now.' left cockpit after resetting parking brake and saw radome underside dented and in contact with roof of tug cabin attendant. I had taken a horizontally held wand displayed by marshaller to mean 'chocks in.' apparently they were not. Contributing to my confusion was low blood sugar. I ate lunch at XA00 abc time and was scheduled to eat on abc - ZZZ leg. Instead training crew took flight and first officer and I deadheaded 3 legs to xyz. Training crew ate meals we would have had. We were finally fed on the way to ZZZ, 9 hours after my last meal. Marshaller stood in front of aircraft under nose instead of to left side of cockpit in full view of captain. For whatever reason, chocks were not placed in a timely manner. A horizontal movement of marshaller's wands was apparently not a 'chocks in place' signal, which I took it to be.

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Original NASA ASRS Text

Title: A B737-400 WAS PARKED ON THE GATE WHEN THE CREW THINKING THE WHEELS WERE CHOCKED RELEASED THE BRAKES ALLOWING THE ACFT TO ROLL FORWARD STRIKING A TUG INCURRING DAMAGE TO THE RADOME.

Narrative: TAXIED TO STOP AT GATE, SET PARKING BRAKE AND SHUT DOWN ENGS. COMPLETED COCKPIT POSTFLT SHUTDOWN PROCS. COMPLETED SHUTDOWN CHKLIST AND RELEASED PARKING BRAKE. ACFT DID NOT MOVE, BUT A SHORT TIME LATER A SCRAPING NOISE WAS HEARD BEHIND INST PANEL. OPENED COCKPIT WINDOW AND ASKED MECH STANDING UNDER JETWAY WHAT WAS GOING ON. HE SAID 'YOU ROLLED FORWARD.' I SAID 'I THOUGHT THE CHOCKS WERE IN,' AND HE SAID 'THEY ARE NOW.' LEFT COCKPIT AFTER RESETTING PARKING BRAKE AND SAW RADOME UNDERSIDE DENTED AND IN CONTACT WITH ROOF OF TUG CAB. I HAD TAKEN A HORIZLY HELD WAND DISPLAYED BY MARSHALLER TO MEAN 'CHOCKS IN.' APPARENTLY THEY WERE NOT. CONTRIBUTING TO MY CONFUSION WAS LOW BLOOD SUGAR. I ATE LUNCH AT XA00 ABC TIME AND WAS SCHEDULED TO EAT ON ABC - ZZZ LEG. INSTEAD TRAINING CREW TOOK FLT AND FO AND I DEADHEADED 3 LEGS TO XYZ. TRAINING CREW ATE MEALS WE WOULD HAVE HAD. WE WERE FINALLY FED ON THE WAY TO ZZZ, 9 HRS AFTER MY LAST MEAL. MARSHALLER STOOD IN FRONT OF ACFT UNDER NOSE INSTEAD OF TO L SIDE OF COCKPIT IN FULL VIEW OF CAPT. FOR WHATEVER REASON, CHOCKS WERE NOT PLACED IN A TIMELY MANNER. A HORIZ MOVEMENT OF MARSHALLER'S WANDS WAS APPARENTLY NOT A 'CHOCKS IN PLACE' SIGNAL, WHICH I TOOK IT TO BE.

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.