B737 MAX 8
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 1320; Flight Crew Type 3870
Communication Breakdown
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural FAR; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Executed Go Around / Missed Approach; General Flight Cancelled / Delayed; General Maintenance Action
Company Policy; Procedure; MEL; Aircraft
Prior to takeoff we had a Left GPS fail. We stopped; ran the QRH; contacted Dispatch and Maintenance and MEL 34-53-01A(C) was issued. We completed the logbook; ran our checklists and departed for ZZZ. During cruise I began to setup for the ILS approach that would be required due to low ceilings. When I switched the frequency to active; I immediately got the LOC / G/S caution flags on the primary flight display. We ran the QRH; which told us we could not do an ILS. We also could not fly an RNAV because of the GPS inop MEL. We called Dispatch and decided we would divert to ZZZ1. We continued without further incident. Here is my issue. Had part of the procedure for the GPS inop had us check other navigation systems (ILS) we would have found the ILS to have also failed. From what I understand they are part of the same (box). Could that be added to Maintenance procedures for MEL 34-53-01. Thank you.
Pilot reported a diversion caused by additional NAV systems inoperative and not addressed in an MEL applied to a GPS system.