Narrative:

I was flying as purser/lead of flight attendant crew. Captain called to have me in cockpit for 'bathroom break' and told me of a situation with the main battery overheating. Flight crew had been in touch with ZZZ maintenance to no avail -- no procedure for main battery overheating. Captain visually checked battery on cargo level and found it smoking, so he disconnected the wires, and temporarily rectified problem. Back in the cockpit as we spoke, the heat indicator rose again and a system warning light came on the panel, forcing him to declare a mayday. We had 20 mins to prepare cabin for emergency landing -- accomplished checklist in 10 mins. Just prior to lowering gear, captain called to inform we would not need to evacuate/evacuation. Landed without incident (and no more smoke in cabin). Yyt fire crew declared us safe to taxi. As far as human factors are concerned, while I gathered crew to inform them of the emergency, etc, a few of our coach passenger could see by sight and airshow that we were no longer continuing to new york and started a wave of panic and grabbing life vests. Luckily, we contained it to that zone, but I did elect to make a second PA to make sure they knew how to operate the vest and, more importantly, when not to. (We had shut down video system when the captain initially explained our situation in his announcement, but it was too late.) approximately 40 vests were out which the passenger would not take off until we were safely on the ground.

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Original NASA ASRS Text

Title: A B777 OVERWATER FLT EXPERIENCES AN OVERHEATING MAIN BATTERY WHICH CAN ONLY BE DISCONNECTED AS AN EMER PROC WITH THE FLT MAKING AN EMER DIVERSION AND LNDG AT CYYT, NF.

Narrative: I WAS FLYING AS PURSER/LEAD OF FLT ATTENDANT CREW. CAPT CALLED TO HAVE ME IN COCKPIT FOR 'BATHROOM BREAK' AND TOLD ME OF A SIT WITH THE MAIN BATTERY OVERHEATING. FLC HAD BEEN IN TOUCH WITH ZZZ MAINT TO NO AVAIL -- NO PROC FOR MAIN BATTERY OVERHEATING. CAPT VISUALLY CHKED BATTERY ON CARGO LEVEL AND FOUND IT SMOKING, SO HE DISCONNECTED THE WIRES, AND TEMPORARILY RECTIFIED PROB. BACK IN THE COCKPIT AS WE SPOKE, THE HEAT INDICATOR ROSE AGAIN AND A SYS WARNING LIGHT CAME ON THE PANEL, FORCING HIM TO DECLARE A MAYDAY. WE HAD 20 MINS TO PREPARE CABIN FOR EMER LNDG -- ACCOMPLISHED CHKLIST IN 10 MINS. JUST PRIOR TO LOWERING GEAR, CAPT CALLED TO INFORM WE WOULD NOT NEED TO EVAC. LANDED WITHOUT INCIDENT (AND NO MORE SMOKE IN CABIN). YYT FIRE CREW DECLARED US SAFE TO TAXI. AS FAR AS HUMAN FACTORS ARE CONCERNED, WHILE I GATHERED CREW TO INFORM THEM OF THE EMER, ETC, A FEW OF OUR COACH PAX COULD SEE BY SIGHT AND AIRSHOW THAT WE WERE NO LONGER CONTINUING TO NEW YORK AND STARTED A WAVE OF PANIC AND GRABBING LIFE VESTS. LUCKILY, WE CONTAINED IT TO THAT ZONE, BUT I DID ELECT TO MAKE A SECOND PA TO MAKE SURE THEY KNEW HOW TO OPERATE THE VEST AND, MORE IMPORTANTLY, WHEN NOT TO. (WE HAD SHUT DOWN VIDEO SYS WHEN THE CAPT INITIALLY EXPLAINED OUR SIT IN HIS ANNOUNCEMENT, BUT IT WAS TOO LATE.) APPROX 40 VESTS WERE OUT WHICH THE PAX WOULD NOT TAKE OFF UNTIL WE WERE SAFELY ON THE GND.

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.