Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 229; Flight Crew Type 229
Distraction
Aircraft Equipment Problem Critical; Deviation - Track / Heading All Types
Flight Crew Became Reoriented
Aircraft
We were flying the POAS 4 Departure Runway 07 [from MROC]. We briefed the POAS 4 Departure; as well as the MROC Runway 07 Departure Procedure on the MROC Station Information. We had everything loaded and configured in the OPC (Operational Program Configuration) and the FMC; including the POAS 4 Departure with all the points verified in the LEGS page of the FMC; as well as the thrust reduction set to 2500 ft AGL in the Takeoff Ref; and everything else in accordance with the MROC Runway 07 Departure Procedure. Our actual takeoff weight was also just 300 pounds shy of our takeoff-limited ATOG (based on obstacle clearance); so we planned and flew a bleeds off takeoff. The ATIS reported winds at something like 100/12; with a temperature of 27 or 28 degrees Celsius.After takeoff; climbing thru about 500 ft AGL; we got a message that appeared in the FMC scratchpad. It said something like 'Route Discontinuity Inserted'. Something changed in the LEGS page as well; but I was concentrating on monitoring the departure to make sure we started the right hand turn on time. This was our first indication that a system was starting to degrade. At the TIO 4 DME; per the Departure Procedure; we initiated the right hand turn to turn back direct to the TIO VOR. At 5500 ft MSL we began accelerating to flaps up maneuvering speed and began cleaning up the flaps. We remained north of the TIO R-113 as we proceeded inbound to the TIO VOR. At some point inbound to the VOR; the entire map display on both the Captain and First Officer display units went blank and displayed some error message on the map display. The FMC on both sides dropped out as well and reverted to the Menu page; with only the DLK (Data Link) and ACMS (Aircraft Condition Monitoring System) options available at LSK (Line Select Key) 2L and LSK 3L. Where the option 'FMC' at LSK 1L is normally located; it was completely blank. We could not engage LNAV OR VNAV and continued using HDG SEL to turn outbound on the TIO R-012; per the POAS 4 Departure. We slightly overshot the R-012 as we crossed the TIO VOR.After about one to two minutes; the map display and FMC on both sides returned to normal operation and function without any intervention by the Pilots. It all happened so fast; and we were concentrating on avoiding the mountainous terrain; staying north of the TIO R-113; and not overspeeding the flaps; that we couldn't properly diagnose what exactly went wrong; and what error messages came up. But we do know that we did lose all map displays and both FMCs during a critical phase of flight in mountainous terrain while doing a special departure procedure. Fortunately we were in daylight VMC conditions. If the event would have occurred in IMC and/or night conditions; it could have been a potentially disastrous outcome.
B737NG Captain reported receiving an error message in the FMC scratchpad; MAP displays went blank; both FMS's dropped out and were unable to engage VNAV and LNAV.  All returned to normal soon after with no input from either pilot.