737 MAX Flight Crew Operations Manual
Supplementary Procedures -
Flight Management, Navigation
SP.11.14
MN-FLT-OH-201
Other Operations
FMC Navigation Check
YA601 - YA648, YA657, YA683, YB111 - YB119, YC095, YC453, YC573, YD256, YF631 - YF801, YK721 - YK728, YK730 - YK737, YK739, YK740, YK751, YK752, YK758, YK760 - YK762, YK764 - YK767, YK769, YK770, YL801 - YL809, YL811 - YL813, YL815 - YN109, YN261 - YN702, YR602 - YR617, YR619, YR624, YR626 - YR628, YR630, YR631, YR634 - YR661,
YR663 - YV671
(SB Changes YK753 - YK756, YL621)
Do the following as needed to ensure navigation accuracy if any alerting
message listed below is shown in the scratch pad or course deviation is
suspected:
• GPS-L INVALID and GPS-R INVALID (both)
• IRS-L DRIFT
• IRS-R DRIFT
• UNABLE REQD NAV PERF - RNP
• VERIFY POS: FMC-FMC
• VERIFY POS: FMC-GPS
• VERIFY POS: FMC-RADIO
• VERIFY POS: IRS-FMC
• VERIFY POS: IRS-IRS
• VERIFY POS: IRS-RADIO
Actual position ................... Determine and compare with FMC position
Determine actual airplane position using raw data from VHF
navigation or ADF radios.
If radio navaids are unavailable:
FMC position ............................... Compare with the IRS position
Use the POS SHIFT page of the FMC CDU. If the two IRS
positions are in agreement and the FMC position is significantly
different, the FMC position is probably unreliable. The POS
SHIFT page may be used to shift FMC position to one of the IRS
positions. This is accomplished by line selecting the IRS or radio
position and then pressing the EXEC Key.
Actual position ....... Confirm with ATC radar or visual reference points.
Navigate using most accurate information available (continue to monitor
FMC position using VOR/ADF raw data displays on non–flying pilot's
navigation display).
CAUTION: Navigating in LNAV mode with an unreliable FMC
position may result in significant navigation errors.
Navigate by conventional VOR/ADF procedures, radar vectors from
ATC, dead reckoning from last known position, and/or use of visual
references.
March 1, 2021