Narrative:

Descending through 25000 ft to gdl, the overheat was lit. The master caution light blinked on and off several times, then came on steady with the overheat/detector annunciator. The cargo fire panel showed the forward B detector light on only. The QRH called for testing the cargo fire warning system which we did. The forward a detector light did not illuminate. Under this situation, the checklist called for running the cargo fire in-flight checklist and treating the problem as a cargo fire. We fired the #1 bottle into the forward compartment, declared an emergency with gdl approach, and asked for the emergency crews to stand by. During the descent, the fire bell would intermittently sound even after being canceled. After ensuring the first officer would handle the radios and aircraft I called the first flight attendant forward and briefed her on the situation. I explained that we thought the indication was false. She later told me the cabin crew searched for and detected no indication of fire/smoke in the cabin. We did not anticipate evacing although it may later become necessary if the fire fighters on the ground saw problems. She left and the cabin crew prepared for a normal landing. ATC turned us over to the tower. They informed us that the equipment was ready. I told them that we would stop and let the emergency crew check us for signs of fire before deciding what to do next. The first officer and I decided that after we stopped, he would prepare the aircraft for evacuate/evacuation and ran the evacuate/evacuation checklist down to the evacuate/evacuation decision while I communicated with the tower. I made a quick announcement on the PA and explained the problem as a bad indication and that the airport safety crews would meet us after we landed. I asked them to remain seated through the inspection and to follow the instructions of the cabin crew. I called gdl operations and quickly explained the situation and that we planned to taxi to the gate and deplaned the customers normally. The first officer called for and we completed the approach and landing checklists and made a normal landing. We stopped the aircraft on the runway. The first officer ran the checklists as briefed while I coordinated through the tower with the fire crews. I also made a 'remain seated' PA. The fire crew determined that we had no indication of fire. We made sure that they did not open the cargo door and stayed away from the running engines. The fire crew followed us to the gate and we deplaned the passenger via the forward door and airstairs. After all the passenger and cabin crew had deplaned, the firefighters opened the cargo doors (while standing by with fire equipment) and determined that there was no fire. Ground crew then unloaded the aircraft.

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Original NASA ASRS Text

Title: A B737-300 ON DSCNT AT FL250 DECLARED AN EMER DUE TO FORWARD CARGO COMPARTMENT FIRE WARNING LIGHT ON, CAUSED BY FALSE WARNING.

Narrative: DSNDING THROUGH 25000 FT TO GDL, THE OVERHEAT WAS LIT. THE MASTER CAUTION LIGHT BLINKED ON AND OFF SEVERAL TIMES, THEN CAME ON STEADY WITH THE OVERHEAT/DETECTOR ANNUNCIATOR. THE CARGO FIRE PANEL SHOWED THE FORWARD B DETECTOR LIGHT ON ONLY. THE QRH CALLED FOR TESTING THE CARGO FIRE WARNING SYS WHICH WE DID. THE FORWARD A DETECTOR LIGHT DID NOT ILLUMINATE. UNDER THIS SIT, THE CHKLIST CALLED FOR RUNNING THE CARGO FIRE INFLT CHKLIST AND TREATING THE PROB AS A CARGO FIRE. WE FIRED THE #1 BOTTLE INTO THE FORWARD COMPARTMENT, DECLARED AN EMER WITH GDL APCH, AND ASKED FOR THE EMER CREWS TO STAND BY. DURING THE DSCNT, THE FIRE BELL WOULD INTERMITTENTLY SOUND EVEN AFTER BEING CANCELED. AFTER ENSURING THE FO WOULD HANDLE THE RADIOS AND ACFT I CALLED THE FIRST FLT ATTENDANT FORWARD AND BRIEFED HER ON THE SIT. I EXPLAINED THAT WE THOUGHT THE INDICATION WAS FALSE. SHE LATER TOLD ME THE CABIN CREW SEARCHED FOR AND DETECTED NO INDICATION OF FIRE/SMOKE IN THE CABIN. WE DID NOT ANTICIPATE EVACING ALTHOUGH IT MAY LATER BECOME NECESSARY IF THE FIRE FIGHTERS ON THE GND SAW PROBS. SHE LEFT AND THE CABIN CREW PREPARED FOR A NORMAL LNDG. ATC TURNED US OVER TO THE TWR. THEY INFORMED US THAT THE EQUIP WAS READY. I TOLD THEM THAT WE WOULD STOP AND LET THE EMER CREW CHK US FOR SIGNS OF FIRE BEFORE DECIDING WHAT TO DO NEXT. THE FO AND I DECIDED THAT AFTER WE STOPPED, HE WOULD PREPARE THE ACFT FOR EVAC AND RAN THE EVAC CHKLIST DOWN TO THE EVAC DECISION WHILE I COMMUNICATED WITH THE TWR. I MADE A QUICK ANNOUNCEMENT ON THE PA AND EXPLAINED THE PROB AS A BAD INDICATION AND THAT THE ARPT SAFETY CREWS WOULD MEET US AFTER WE LANDED. I ASKED THEM TO REMAIN SEATED THROUGH THE INSPECTION AND TO FOLLOW THE INSTRUCTIONS OF THE CABIN CREW. I CALLED GDL OPS AND QUICKLY EXPLAINED THE SIT AND THAT WE PLANNED TO TAXI TO THE GATE AND DEPLANED THE CUSTOMERS NORMALLY. THE FO CALLED FOR AND WE COMPLETED THE APCH AND LNDG CHKLISTS AND MADE A NORMAL LNDG. WE STOPPED THE ACFT ON THE RWY. THE FO RAN THE CHKLISTS AS BRIEFED WHILE I COORDINATED THROUGH THE TWR WITH THE FIRE CREWS. I ALSO MADE A 'REMAIN SEATED' PA. THE FIRE CREW DETERMINED THAT WE HAD NO INDICATION OF FIRE. WE MADE SURE THAT THEY DID NOT OPEN THE CARGO DOOR AND STAYED AWAY FROM THE RUNNING ENGS. THE FIRE CREW FOLLOWED US TO THE GATE AND WE DEPLANED THE PAX VIA THE FORWARD DOOR AND AIRSTAIRS. AFTER ALL THE PAX AND CABIN CREW HAD DEPLANED, THE FIREFIGHTERS OPENED THE CARGO DOORS (WHILE STANDING BY WITH FIRE EQUIP) AND DETERMINED THAT THERE WAS NO FIRE. GND CREW THEN UNLOADED THE ACFT.

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.