During climb in a B747 cargo plane; the crew received a master warning for cargo fire.

Attributes
ACN	1355329
Time
Date	201605
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZZ.Airport
State Reference	FO
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B747-400
Operating Under FAR Part	Part 121
Flight Phase	Takeoff
Flight Plan	IFR
Component
Aircraft Component	Cargo Compartment Fire/Overheat Warning
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe

Narrative:

Immediately after takeoff; we received a master warning for cargo fire aft. We knew there was much condensation prior to the flight and used the [company advisories] to mitigate. We proceeded with the QRH items and the warning ceased. Approximately 2 minutes later we received the master warning and cargo fire aft message again followed by a new message fire warning main deck. When we pulled up the status page there was indications of multiple cargo loops failed. I made the decision to return and have the fire trucks meet us. All QRH items were followed but no depressurization. Upon landing I had the fire department clear the airplane and then maintenance proceeded to deal with the issues.[company advisories] for this aircraft had been followed and maintenance ended up replacing 4 detectors.

Original NASA ASRS Text

Title: During climb in a B747 cargo plane; the crew received a master warning for cargo fire.

Narrative: Immediately after takeoff; we received a Master Warning for Cargo Fire Aft. We knew there was much condensation prior to the flight and used the [company advisories] to mitigate. We proceeded with the QRH items and the warning ceased. Approximately 2 minutes later we received the Master Warning and Cargo Fire Aft message again followed by a new message Fire Warning Main Deck. When we pulled up the status page there was indications of multiple Cargo Loops failed. I made the decision to return and have the fire trucks meet us. All QRH items were followed but no depressurization. Upon landing I had the fire department clear the airplane and then Maintenance proceeded to deal with the issues.[Company advisories] for this aircraft had been followed and maintenance ended up replacing 4 detectors.

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.