Narrative:

In cruise at FL370 captain was pilot flying. Fire alarm sounded. Alarm was silenced and an aft cargo fire was indicated. QRH was called for. Light extinguished momentarily then fire bell rang again. We notified ATC [of our] decision to land at phx. First officer (first officer) ran the appropriate check list and ATC was handled by captain (ca). Upon completion of the checklist ca informed flight attendants (flight attendant's) of the situation; time to landing (11 minutes) and that landing should be normal. A PA to the passengers was made about the landing and they were informed to follow flight attendant instruction and remain seated upon landing. Also mentioned the safety vehicles would be near the aircraft upon landing. Informed dispatch via ACARS with description and time to arrival. Asked for arff (airport rescue firefighting). First officer got current field info. Ca set up approach and landing data. Descent was made at .78/320 KTS. ATC (on the discreet frequency) cleared us ILS to runway X. Descent and before landing checklists were run. Landing was normal. Ca stopped on the runway. Arff approached the aircraft to check for heat in the aft cargo. None was detected. We were cleared to taxi to gate. During taxi the fire bell sounded. Aft cargo fire indication again. We stopped the aircraft on taxiway B immediately and asked to have the arff do another check to confirm we did not have a fire. The check was negative. The first officer called company operations to make sure ramp personnel did not open the cargo door without the arff there. Arff followed us to the gate and uneventfully opened the aft cargo. They donned protection and entered the aft cargo to ensure no fire existed. No issues. Passengers were deplaned upon gate arrival without incident. The discrepancies were noted in the logbook. Crew was met by managers and contacted by union reps. Ca and first officer were removed from the sequence and fas continued after a delay. Most likely a problem with the fire detector loop in the aft cargo compartment.

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Original NASA ASRS Text

Title: B737-800 flight crew reported diverting to an alternate airport after receiving an aft cargo compartment fire warning. After landing warning was found to be false.

Narrative: In cruise at FL370 Captain was Pilot Flying. Fire alarm sounded. Alarm was silenced and an aft cargo fire was indicated. QRH was called for. Light extinguished momentarily then fire bell rang again. We notified ATC [of our] decision to land at PHX. First Officer (FO) ran the appropriate check list and ATC was handled by Captain (CA). Upon completion of the checklist CA informed Flight Attendants (FA's) of the situation; time to landing (11 minutes) and that landing should be normal. A PA to the passengers was made about the landing and they were informed to follow FA instruction and remain seated upon landing. Also mentioned the safety vehicles would be near the aircraft upon landing. Informed Dispatch via ACARS with description and time to arrival. Asked for ARFF (Airport Rescue Firefighting). FO got current field info. CA set up approach and landing data. Descent was made at .78/320 KTS. ATC (on the discreet frequency) cleared us ILS to Runway X. Descent and before landing checklists were run. Landing was normal. CA stopped on the runway. ARFF approached the aircraft to check for heat in the aft cargo. None was detected. We were cleared to taxi to gate. During taxi the fire bell sounded. Aft cargo fire indication again. We stopped the aircraft on taxiway B immediately and asked to have the ARFF do another check to confirm we did not have a fire. The check was negative. The FO called company operations to make sure ramp personnel did not open the cargo door without the ARFF there. ARFF followed us to the gate and uneventfully opened the aft cargo. They donned protection and entered the aft cargo to ensure no fire existed. No issues. Passengers were deplaned upon gate arrival without incident. The discrepancies were noted in the logbook. Crew was met by managers and contacted by union reps. CA and FO were removed from the sequence and FAs continued after a delay. Most likely a problem with the fire detector loop in the aft cargo compartment.

Data retrieved from NASA's ASRS site 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.