Date: 201808
Local time of day: 1201-1800
Location: ZZZZ.ARTCC, FO
Flight conditions: Marginal
Weather elements / visibility: Rain
Light: Daylight
Aircraft: B747-800 Advanced
Operator: Air Carrier
Operating under: Part 121
Mission: Cargo / Freight / Delivery
Flight phase: Climb
ATC / advisory: TRACON ZZZZ
Aircraft component: FMS/FMC
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Detector: Person Flight Crew; Person Observer
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Overcame Equipment Problem; Flight Crew Became Reoriented; Flight Crew FLC Overrode Automation
Contributing factors: Weather; Aircraft
Primary problem: Aircraft

Narrative: Just after takeoff we had a dual FMC failure. Captain was pilot flying and took control of aircraft while both First Officers ran checklists and com. Captain asked NFP (non-flying pilot) to quickly tell ATC we have lost all navigation capability and get a vector. Busy frequency and when able to broadcast he was unable to transmit. Observer FO (First Officer) took communications and told ATC. By this time ATC could see we were off course and asked if we had terrain ahead in sight and we replied yes and could maintain clearance. CA (Captain) started a turn to [the] right. ATC had us turn back to heading 140 for a moment and then 090 climb to 9;000 feet. At this time we got basic Nav back per checklist and continued on course. Contacted Dispatch; [Maintenance]; [Chief Pilot] via SATCOM. Elected to continue at least to [an alternate airport] if not all the way to [our destination]; had lots of fuel to burn or dump regardless. We had concerns about class 2 Nav without FMC limitations in Vol 1. About 1hr into flight recovered L FMC only and continued to [our destination]. Heavy rain [at origin airport] and we suspect that water got into E/E [Electrical/Electronic] compartment?Be more proactive during heavy rain to ensure ground crews and flight crew keep L1 door shut. Now that myself and [the] crew have experienced a dual FMC failure at one of the worst times of a flight; I will certainly be better prepared in the future. Thankful for a good experienced crew and CRM. We talked it through once established on a safe heading and altitude and got the company personnel involved via SATCOM.


Second narrative: I was in the observer's seat. There had been moderate to heavy rain from the time we reached the aircraft until departure. On takeoff roll; I noticed the flaps indication on the upper EICAS [Engine Indicating and Crew Alerting System] flash to the expanded view; momentarily; three times. I took note; and decided to wait until airborne to mention it. Shortly after takeoff; at about 1;000 feet; we got the EICAS message 'NO LAND 3.' Shortly thereafter; several more EICAS messages appeared; including AUTOTHROTTLE and AUTOPILOT. Captain manually disengaged the AP (autopilot); FO (First Officer) cycled the FDs (flight displays). Captain attempted to re-engage the AP; but by then the CDUs (control display panels) read 'TIMEOUT-RESELECT' and all of the Nav data had dropped from both NDs (navigation displays). Captain advised that his plan was to continue hand-flying; and asked the FO to advise ATC that we needed a vector. FO tried to; but found that he was unable to transmit. I was able to tell them that we needed a vector because of a navigation system failure; but there was some confusion. The controller didn't give us a vector right away; but advised that we were below the minimum altitude for that sector; and asked if we could see the terrain and maintain clearance. I advised that we could; and he gave us a heading of 140. After a few moments; he said that we were now above the minimum altitude and gave us a new heading of 090; and I believe an altitude of 7;000. By now the FO in the right seat had the use of the radio again; and we continued the climb. He also began running the ECL (Electronic Checklist); which regained us the use of the flight plan and the AP; but not the autothrottle. With a course visible on the ND; we elected to initially continue on course using HDG and FLCH. Once things had calmed down a bit; the FO took over flying and radio duties while the Captain made a SATCOM call to company. As we continued; we considered alternates and fuel dump requirements; but about an hour into the flight we regained use of the left FMC. At this point; we re-engaged LNAV; VNAV; and autothrottles; and decided to continue to [our destination].


Synopsis: B747 flight crew reported that during climb the aircraft lost all navigation systems and had a dual FMC failure.