B747-400
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Other / Unknown
Flight Crew Became Reoriented
Aircraft; Human Factors
Approximately three hours into the flight off the coast of Canada we received a Main Deck Fire warning. While the flying crew began the checklist I left the cockpit to go investigate. While opening the door I informed the other crewmembers [aboard] that we had a possible fire on the main deck. After assessing the door for signs of smoke I went down to the main deck and grabbed the PBE box and a fire extinguisher. I walked down the main deck looking for signs of fire. After walking the freight I found no indications of fire or smoke. About this time I was joined by three other crewmembers so I elected to go back up to the cockpit to inform the pilots that no fire or smoke was seen. I then retrieved the ice spotlight from the upper deck and went back down to the main deck to continue looking for signs of smoke or fire. After a thorough search none were found. The Check Airman contacted [Operations] by SAT phone and the decision was made to continue on to destination. We checked the main deck every 30 minutes for the rest of the flight. I believe that we handled the situation well. The only possible problem is the wording of the checklist. According to it we should have started an immediate diversion. If it had been a cargo compartment fire or only two pilots on board the decision to follow the checklist and divert immediately would have been taken with alacrity. However; with a large group of supernumeraries on board we were able to ascertain that the fire indication was an anomaly. I believe that the checklist should perhaps be rewritten to allow for the possibility that there are additional crewmembers on board to assess the veracity of intermittent warnings.
B747-400 Relief Pilot experiences a Main Deck Fire warning and goes to investigate; informing other personnel aboard of the issue. No smoke or fire is found and the reporter takes exception to the checklist requirement to begin an immediate diversion.