Date: 201811
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Training / Qualification; Confusion
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Pre-flight
Result: General None Reported / Taken
Contributing factors: Company Policy; Manuals; Procedure; Human Factors
Primary problem: Manuals

Narrative: This was the first flight on a Max for both pilots. Unfamiliarity with flight deck displays led to confusion about display annunciations and switch function. The Flight Manual does not address at least one annunciation; or the controls for the display--or if it does; neither pilot could find the explanation. I have spent literally days looking for an explanation; could not find one; and that is why I wrote this report. It shouldn't be this hard to figure out what I'm looking at.On the First Officer side ND; on the ground only; there is a MAINT annunciation. We both saw it; couldn't find any immediate explanation for it on the ground; and didn't address it until airborne. I researched the FM (Flight Manual) for an explanation; accomplishing a word search of the term MAINT. There are only two references I could find: the overhead MAINT light (a no go item) and the CDS MAINT light (a QRH item). There is no explanation of the ND MAINT annunciation. We spent the entire hour flight trying to find the meaning of this annunciation and came up empty handed. We determined to check it out once we landed (if the light came on again). Sure enough; after parking; the MAINT annunciation came back on the ND display. We called Maintenance to check out the light. We waited to make an ELB entry; unsure if one was required. Turned out; an ELB entry was not required.The mechanic explained the light was part of a menu for maintenance use only on the ground. In addition; there are two selector knobs that are under-explained (i.e.; not explained) in the manual; and we were uncertain what their purpose was. One is under the Fuel Flow switch and the other under the MFD/ENG TFR display switch. These knobs don't seem to work in flight. The First Officer offered to hit the SEL function in flight; to test it out; but I thought something irreversible or undesirable might happen (not knowing what we were actually selecting); so we did not try it out in flight. The mechanic later explained SEL on the First Officer side was used on the ground by maintenance to toggle between the maintenance functions. I forgot to ask what my side did; and still don't know.Finally; in the Captain's preflight procedure in the bulletin; it says; 'Selector... C'. What selector is this referring to? Is this the same selector under the Fuel Flow switch; (which is shown in the MAX panels on the L position; as if that is the normal position?) This is very poorly explained. I have no idea what switch the preflight is talking about; nor do I understand even now what this switch does.I think this entire setup needs to be thoroughly explained to pilots. How can a Captain not know what switch is meant during a preflight setup? Poor training and even poorer documentation; that is how. It is not reassuring when a light cannot be explained or understood by the pilots; even after referencing their flight manuals. It is especially concerning when every other MAINT annunciation means something bad. I envision some delayed departures as conscientious pilots try to resolve the meaning of the MAINT annunciation and which switches are referred to in the setup.




Synopsis: B737MAX Captain reported confusion regarding switch function and display annunciations related to 'poor training and even poorer documentation'.