Narrative:

While cruising at FL390 in a widebody transport freighter aircraft, the fire warning bell and light suddenly came on. So called out 'zone 3 main deck cargo fire warning.' the captain heard only '3' and thinking engine fire, began pulling power on #3 engine. After some confusing moments, the true situation was understood by all. The captain insisted on flying the aircraft so I assisted the so in running the emergency checklist. After having declared emergency with tokyo center and requesting clearance to nagoya, the captain requested that I fly the aircraft briefly while he tried to adjust his oxygen mask which had 'come apart' and was unusable. After satisfactorily (for the moment) fixing the mask, he again took control of the aircraft. To facilitate descent, he asked for gear down. I complied, but without checking the gear speed placard limitation. After approximately 10 mins, the cargo fire warning light went out, no smoke or fumes noticed in the cockpit. On approach, it was finally realized the gear still indicated red/unsafe from when it was lowered for the emergency descent. Use of alternate gear extension procedure was successful but we then realized that gear extension was made above placarded gear extension speed. This speed is the same for all models of the widebody transport except the freighter, which has a lower gear extension speed. I had requested through several ATC agencies that emergency equipment be standing by but up until short final, no cockpit discussion of aircraft evacuate/evacuation, where we would stop, etc, was made. After normal landing, no evidence of fire was found. Fire detection system checked good by maintenance personnel. Recommendations. Preflight check of oxygen mask includes putting it on. It can be a pain restowing (on this airplane) but it could be your life. When an emergency occurs, ensure all crew members understand the problem. Ensure someone designated to fly the airplane and someone to assist with emergency procedures (3 man crews). It's usually done this way in the simulator but wasn't done this time. Early on, brief all aspects pertinent to emergency, ie, aircraft evacuate/evacuation upon landing so everyone understands how things will proceed.

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Original NASA ASRS Text

Title: ACR WDB FREIGHT ACFT GOT A CABIN FIRE WARNING AT CRUISE ALT. FLC DIVERTED TO ALTERNATE WHERE NO EVIDENCE OF FIRE WAS FOUND.

Narrative: WHILE CRUISING AT FL390 IN A WDB FREIGHTER ACFT, THE FIRE WARNING BELL AND LIGHT SUDDENLY CAME ON. SO CALLED OUT 'ZONE 3 MAIN DECK CARGO FIRE WARNING.' THE CAPT HEARD ONLY '3' AND THINKING ENG FIRE, BEGAN PULLING PWR ON #3 ENG. AFTER SOME CONFUSING MOMENTS, THE TRUE SITUATION WAS UNDERSTOOD BY ALL. THE CAPT INSISTED ON FLYING THE ACFT SO I ASSISTED THE SO IN RUNNING THE EMER CHKLIST. AFTER HAVING DECLARED EMER WITH TOKYO CENTER AND REQUESTING CLRNC TO NAGOYA, THE CAPT REQUESTED THAT I FLY THE ACFT BRIEFLY WHILE HE TRIED TO ADJUST HIS OXYGEN MASK WHICH HAD 'COME APART' AND WAS UNUSABLE. AFTER SATISFACTORILY (FOR THE MOMENT) FIXING THE MASK, HE AGAIN TOOK CTL OF THE ACFT. TO FACILITATE DSCNT, HE ASKED FOR GEAR DOWN. I COMPLIED, BUT WITHOUT CHKING THE GEAR SPD PLACARD LIMITATION. AFTER APPROX 10 MINS, THE CARGO FIRE WARNING LIGHT WENT OUT, NO SMOKE OR FUMES NOTICED IN THE COCKPIT. ON APCH, IT WAS FINALLY REALIZED THE GEAR STILL INDICATED RED/UNSAFE FROM WHEN IT WAS LOWERED FOR THE EMER DSCNT. USE OF ALTERNATE GEAR EXTENSION PROC WAS SUCCESSFUL BUT WE THEN REALIZED THAT GEAR EXTENSION WAS MADE ABOVE PLACARDED GEAR EXTENSION SPD. THIS SPD IS THE SAME FOR ALL MODELS OF THE WDB EXCEPT THE FREIGHTER, WHICH HAS A LOWER GEAR EXTENSION SPD. I HAD REQUESTED THROUGH SEVERAL ATC AGENCIES THAT EMER EQUIP BE STANDING BY BUT UP UNTIL SHORT FINAL, NO COCKPIT DISCUSSION OF ACFT EVAC, WHERE WE WOULD STOP, ETC, WAS MADE. AFTER NORMAL LNDG, NO EVIDENCE OF FIRE WAS FOUND. FIRE DETECTION SYS CHKED GOOD BY MAINT PERSONNEL. RECOMMENDATIONS. PREFLT CHK OF OXYGEN MASK INCLUDES PUTTING IT ON. IT CAN BE A PAIN RESTOWING (ON THIS AIRPLANE) BUT IT COULD BE YOUR LIFE. WHEN AN EMER OCCURS, ENSURE ALL CREW MEMBERS UNDERSTAND THE PROBLEM. ENSURE SOMEONE DESIGNATED TO FLY THE AIRPLANE AND SOMEONE TO ASSIST WITH EMER PROCS (3 MAN CREWS). IT'S USUALLY DONE THIS WAY IN THE SIMULATOR BUT WASN'T DONE THIS TIME. EARLY ON, BRIEF ALL ASPECTS PERTINENT TO EMER, IE, ACFT EVAC UPON LNDG SO EVERYONE UNDERSTANDS HOW THINGS WILL PROCEED.

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.