Narrative:

At cruise 45 minutes into flight had a status message of 'overheat circuit right 1 and fire loop 1 eng right'. Sent maintenance a message and continued. 2+30 into flight got EICAS message 'det fire eng right'. Consulted with maintenance and operations and determined we had no fire detection on right engine. [We were] concerned due to time lapse between status message and EICAS message. [We] still had 4+30 enroute over sparsely populated area with few airports to divert to. Consulted with duty officer and determined safest course of action to divert to [a nearby airport] rather to continue with no fire detection on right engine. Upon landing stopped on taxiway and had fire and rescue inspect right engine after we shut it down to confirm no fire indication prior to entering ramp. [We] advised ATC reason to divert due to maintenance precaution.

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Original NASA ASRS Text

Title: B777 First Officer reported losing fire detection on right engine 2 1/2 hours into a long international flight. They elected to declare an emergency and divert to a nearby airport.

Narrative: At cruise 45 minutes into flight had a status message of 'overheat Circuit R 1 and Fire Loop 1 Eng R'. Sent Maintenance a message and continued. 2+30 into flight got EICAS message 'Det Fire Eng R'. Consulted with Maintenance and Operations and determined we had no fire detection on right engine. [We were] concerned due to time lapse between status message and EICAS message. [We] still had 4+30 enroute over sparsely populated area with few airports to divert to. Consulted with Duty Officer and determined safest course of action to divert to [a nearby airport] rather to continue with no fire detection on right engine. Upon landing stopped on taxiway and had fire and rescue inspect right engine after we shut it down to confirm no fire indication prior to entering ramp. [We] advised ATC reason to divert due to maintenance precaution.

Data retrieved from NASA's ASRS site as of July 2013 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.