Date: 201605
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Dawn
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: FMS/FMC
Component problem: Design
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Human-Machine Interface; Training / Qualification; Communication Breakdown
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Human Factors; Procedure; Aircraft
Primary problem: Human Factors

Narrative: On this flight; the FMC execute light was disabled for most of the flight. This report addresses the failures of the flight manual; cross checks; or Maintenance Control to address any type of correction for this. It is presumed that reloading the approach; which was done just prior to descent; corrected the issue; and that loading the arrival and departure prior to the winds actually caused the issue; but that is indeterminable. After the route was loaded on this flight; a RTE DATA prompt was not available; so the rest of the box was loaded; including both the departure and arrival. After that; the prompt appeared and the winds were loaded. The final weights and takeoff data required manual loading and after takeoff; it appeared that the execute light did not work. After exploring the system; it was discovered that portions of the FMC would execute; but not others. The navigation system worked properly; and we were able to stay on our route in RVSM airspace. The impact would have involved either using conventional navigation in the terminal area; or not being able to modify our arrival in the terminal area. After consulting the book and QRH; we could find nothing addressing this issue.We contacted Maintenance Control regarding this issue. It took nearly 30 minutes to get a response; and only after prompting from Dispatch. Their response was disappointing; especially since this seems like an issue that may have occurred on numerous occasions before. Their support was also inaccurate; referring to a route purge prompt; which did not exist. However; they did inspire us to try reloading the approach and arrival; but not on their accord; only on our connection of the differing solutions. The book and QRH did not present an easy to find solution to this issue. With hundreds of pages of NORMAL procedures; and charts that few can understand; the book is a lot like searching a 5 year old's Lego box for the Luke Skywalker light sabre. Perhaps I am revealing my ignorance here; but a response like; 'ya; that's clearly covered' doesn't help me with this or especially the next problem that may occur. If there is something that actually addresses this particular issue; I could not find it with multiple searches and looking in the book for over an hour. We need a useful manual; and a section of system anomalies that is easy to find.Flying this aircraft requires a great deal of colloquial knowledge; with differences in the FMC and LNAV/VNAV systems creating many issues. Burying them in the book only makes us bury them; and thus not report them when we fly. This is one more of those issues. With all of these little secrets in each model aircraft; the error rate increases greatly. I'm sure this isn't the first time that my issue has occurred; but my interaction with Maintenance Control and the book would suggest otherwise.   The following items should be reviewed:1) The flight manual needs to show this as an anomaly; make it searchable in the book; and ensure it is trained and noted regularly so we all know where to find these issues.2) Maintenance Control needs the right personnel to provide prompt assistance that is accurate and doesn't take 30 minutes to address; even when there is a shift change. An acknowledgement of receipt of the message and a standby should be required; so we know we aren't being ignored.3) The loading of the FMC should be fixed so it is does not inhibit the EXECUTE light. It shouldn't matter how the FMC is loaded.4) Further training could be addressed in perhaps a recurrent LOE; where anomalies are addressed.




Synopsis: B737 Captain reported the FMC execute light was disabled for most of the flight.