Boeing 737 FMC Messages

FMC messages on Boeing 737 aircraft inform the flight crew of degraded system operations or data input errors. These messages appear in the CDU scratchpad and are classified as:

FMC Alerting messages
FMC Entry error messages
FMC Advisory messages
FMC data link messages (alerting and advisory)
ATC data link messages (alerting only)
FMC Navlink ACARS messages (active, inactive, and scratchpad)

Messages are prioritized based on importance:

Alerting messages (most important)
Entry error messages
Advisory messages (least important)

When multiple messages are present, less important ones are replaced in the scratchpad when the CLR key is pressed or the issue is resolved.

The amber FMC alert light on each pilot’s main panel illuminates for alerting messages.
The CDU MSG light illuminates for all FMC messages.
Messages can be cleared or corrected to cancel them.

Note: The following tables are general lists of FMC messages; some may not apply to all FMC configurations.

FMC Alerting Messages

FMC alerting messages indicate conditions that significantly impact FMC operation. These messages:

Displayed in the CDU scratchpad.
Trigger the amber FMC alert light on each pilot’s main panel.
Illuminate the message (MSG) lights on both CDUs.

To clear the message:

Use the CLR key or correct the condition.
When manually entering data into the scratchpad, the message temporarily disappears but will reappear once the data is removed unless the issue is resolved.

ALERTING MESSAGE	CAUSE	CORRECTIVE ACTION
CRZ ALT CHANGED TO XXXXX	An altitude constraint added due to entering a new company route, a new destination airport, or selection of a new procedure conflicts with the cruise altitude, resulting in automatically raising the cruise altitude to match the highest waypoint altitude constraint in the mod plan, when not in active descent.	Clear the message. Verify MCP cruise altitude.
CHECK ALT TGT	VNAV disengages while airplane is between MCP and FMC altitudes or VNAV button pressed while airplane is between MCP and FMC altitudes.	Clear the message.
CYCLE IRS OFF–NAV	IRS is unable to complete alignment under current conditions.	Cycle IRS mode selector to “OFF” and back to “NAV.”
DATA BASE INVALID	The automatic validity test of the permanent navigation database has failed.	Advise maintenance personnel to check the FMC and reload the database, as required. If desired, consider the use of the temporary nav database.
DISCO INSRTD AFTR XXXXX (waypoint identifier)	A ROUTE DISCONTINUITY has been inserted into the flight plan due to undefined termination of a downpath leg or a triple waypoint BYPASS.	Select the RTE or RTE LEGS pages and modify the waypoints for a continuous route.
DISCONTINUITY	Passing the last waypoint in the route prior to a ROUTE DISCONTINUITY (LNAV disengages) or pressing LNAV while in a discontinuity.	Select the RTE LEGS page. Enter the desired active waypoint into the box prompts. Correct any ROUTE DISCONTINUITY and EXECute. Reengage LNAV.
DRAG REQ AFTER XXXXX	A waypoint speed constraint greater than 10 knots above the predicted speed exists at waypoint XXXXX.	Modify flight plan as required. Clear the message.
END OF OFFSET	Two minutes prior to passing offset leg termination.	Confirm clearance.
END OF ROUTE	LNAV engaged and passing the last waypoint in the route (LNAV disengages).	Select the RTE LEGS page. Enter the desired active waypoint into the dash prompts and EXECute. Reengage LNAV.
ENG OUT SID MOD	An engine–out SID has been automatically inserted into the flight plan as a modification.	Clear the message.
ENTER IRS POSITION	IRS in the alignment mode needs present position to complete alignment. Previous present position entry was not received back from the IRS.	Enter IRS present position into the scratchpad pad and line select 4R on the POS INIT page of the CDU. If present position was previously entered, overwrite displayed data. If necessary, enter present position directly into the IRS control /display unit.
FMC APP/TUNE DISAGREE (U13.0)	An approach that utilizes FMC generated glide path is in the active flight plan but an approach navaid (ILS/GLS) has been tuned with G/S ON.	Confirm the tuned frequency and approach selected in the FMC are both consistent with the actual approach intended to be flown. Resolve tuning or approach selection inconsistency. Clear the message.
FMC APP/TUNE DISAGREE (U14.0 and above)	An approach that utilizes FMC generated glide path is in the active flight plan but an approach navaid (ILS/GLS/LPV) has been tuned with G/S ON.	Confirm the tuned frequency and approach selected in the FMC are both consistent with the actual approach intended to be flown. Resolve tuning or approach selection inconsistency. Clear the message.
FMC DISAGREE	During approach or on the ground, monitored parameters required for dual FMC operation are in disagreement. (Dual FMC as installed) Message will remain displayed until the condition has been resolved. The FMC does not check for mach and indicated airspeed miscompares on the ground.	Monitor FMCs closely. Both FMCs remain online. Limit approaches to single FMC only. If desired, revert to SINGLE FMC OPERATION in this section.
FMC DISAGREE – VERTICAL	A vertical deviation, FMC Airspeed, or FMC Mach value disagreement between the FMCs by more than the allowed tolerance occurs and long enough that all attempts to resynchronize failed while the aircraft in a path descent. Message display is inhibited when in the Approach Nav environment. (dual FMC as installed)	Do not move the FMC source select switch. Monitor crossing altitudes to ensure compliance.
FMC POS/RW DISAGREE	Position information is contradictory.	Refer to FMC Navigation Check Supplementary Procedure.
FUEL DISAGREE	The totalizer fuel quantity and the FMC calculated fuel quantity disagree. Illuminates the FMC P/RST Light. Message displayed on Engine display.	Refer to FUEL DISAGREE non-normal checklist in the QRH. The Engine Display message will remain until the condition is no longer valid.
GPS-L INVALID GPS-R INVALID	FMC is no longer receiving valid information from the displayed GPS system.	Clear the message. For ADS-B operations (if installed), when one GPS is invalid, ensure that the transponder selector is positioned to the side with the valid GPS. For dual GPS installations, if both GPS-L INVALID and GPS-R INVALID messages show, refer to FMC Navigation Check supplementary procedure. For single GPS installations, refer to FMC Navigation Check supplementary procedure
INSUFFICIENT FUEL	FMC fuel at the destination is predicted to be less than 2000 lbs/900 kilograms. Scratchpad message shows for Active and Mod Flight Plan. Illuminates the FMC P/RST Light for Active and Mod Flight Plan. Message displayed on Engine display for the Active Flight Plan only.	Refer to INSUFFICIENT FUEL non-normal checklist in the QRH. The Engine Display message will remain until the condition is no longer valid.
IRS MOTION	IRS has automatically restarted the alignment due to detection of excessive motion.	Clear message and attempt to reduce airplane movement, if practicable.
IRS-(L or R) DRIFT	An FMC has detected that the IRS-(L or R) position or velocity data is unreasonable, and deselected IRS-(L or R) due to velocity divergence or position blunder checks.	Refer to FMC Navigation Check Supplementary Procedure.
IRS POS/ORIGIN DISAGREE	Position information is contradictory.	Refer to FMC Navigation Check Supplementary Procedure.
LNAV BANK ANGLE LIMITED	LNAV is engaged and the airplane is not on a lateral offset and is not near or in an orbit or hold and the airplane is within 5 minutes or less from an LNAV guided course change, and will exceed the airway/route boundaries for non-flyover turns less than or equal to 135 degrees due to performance limited bank angle. This message does not apply to fixed radius turns.	Review the LNAV course change. If course change exceeds airway/route boundary, consider flight plan change.
MAX ALT FLXXX (flight level value)	Altitude intervention (as installed) attempt to raise cruise altitude when MCP altitude is above maximum altitude.	Clear the message.
MISSED CAPTURE	Proper localizer capture maneuver was performed, but the AFDS did not capture.	Clear the message
MODEL/ENG DATA INVALID	A valid performance database is not available.	Contact maintenance personnel.
NAV DATA OUT OF DATE	Effectivity dates of nav database do not agree with date input from clock.	Check the IDENT page and reverse the dates for ACTIVE NAV DATA if required.
NAV INVALID–TUNE XXXXX (navaid identifier)	FMC is unable to auto–tune or receive the navaid for a RNAV or VOR approach procedure.	Cross–check radios and manually tune the desired navaid.
NO VNAV AFTER XXXXX,	The descent path is monitored independent of path construction for the following scenarios: – an “at”, “at or above”, “at or below” or “window” constraint is violated- a navigation data base gradient (vertical angle) is violated If a violation is detected and not resolved, VNAV will disconnect after the point of the violation. The alerting message is displayed one minute prior to the violation.	After sequencing waypoint XXXXX, VNAV INVALID – PERF logic applies: Pilot should reenter the CI using either the previous CI displayed or enter a new CI. Reengage VNAV when change has been EXECuted.
OAT DISAGREE – DELETED	A check of entered OAT versus sensed OAT occurs after first engine start. A difference of +/- 6 degrees Celsius between the OAT value on the N1 LIMIT / TAKEOFF REF page and the engine temperature sensors.	Enter updated/corrected OAT on the N1 LIMIT page.
OVERSPEED DISCONNECT	During path descent and above or below the speed restriction altitude, VNAV disengages when airspeed exceeds FMC speed restriction by more than 15 knots.	Manually reduce speed and reengage VNAV.
PARTIAL ROUTE X LOADED	A route is loaded into the active/inactive RTE 1 or 2 flight plan buffer which references data not contained in any of the databases.	Clear the message.
PERF DEFAULTS INVALID	Validity check of performance defaults database has failed.	Contact maintenance personnel.
RESET MCP ALT	During the FMC cruise phase with VNAV engaged, when within 5 NM of the top-of-descent point without selecting a lower altitude on the AFDS MCP.	Select lower MCP altitude values as clearances permit.
RTA UNACHIEVABLE	The RTA is not in the computed RTA window under current parameters.	Enter an achievable RTA or discontinue the RTA mode of navigation. Adjust parameters to meet the RTA.
RW/APP TUNE DISAGREE	During approach, manual tuned approach frequency or channel does not match active flight plan.	Clear the message and select correct approach frequency.
RW/APP CRS ERROR	During approach, MCP selected course does not match front course for the approach in the active flight plan.	Clear the message and select correct MCP course.
SCANNING DME FAIL	Inputs from both frequency scanning DME radios have failed.	Clear the message and check position. Radio updating of FMC position is not available.
SELECT MODE AFTER RTA	RTA mode has been discontinued due to sequencing of RTA waypoint or RTA waypoint has been removed from the flight plan.	Select alternate performance mode. (ECON, manual speed, etc.)
SINGLE FMC OPERATION	The primary FMC has determined that the secondary FMC is not available. (Dual FMC as installed)	If the FMC source selector switch is in the “Normal” position, move to “BOTH ON L”. No action is required if the FMC source selector switch is already positioned to “BOTH ON L” or “BOTH ON R”.
SW OPTIONS INVALID	The CRC performed during power up BIT on the current software options data base has failed, or the CRC of the software options data base that has been loaded via the data loader has failed.	Reload the FMC OPC software by maintenance.
THRUST REQUIRED	Airplane is in an underspeed condition.	Clear the message. Increase airspeed to within 15 knots of speed target.
UNABLE HOLD AIRSPACE	The lateral predicted hold path using the bank angle limit causes protected airspace to be exceeded.	Review the holding pattern. If holding pattern exceeds allowable holding airspace, consider flight plan change.
UNABLE NEXT ALTITUDE	Unable to meet the next flight plan altitude constraint in a VNAV climb or descent. The message appears only with VNAV engaged.	Clear the message and review the prediction. For undershoot condition during climb, consider selection of MAX RATE CLB or MAX ANGLE CLB, or a different N1 limit as appropriate.
UNABLE PROC AIRSPACE	Minimum procedure turn built by guidance exceeds the allowable excursion distance.	Modify flight plan as required. Clear the message.
UNABLE YYY KTS AT XXXXX	Next waypoint speed restriction (speed YYY, at waypoint XXXXX) cannot be met.	Modify flight plan as required. Clear the message.
UNABLE REQD NAV PERF–RNP (U13 and later)	FMC actual navigation performance is not sufficient for the displayed RNP. VT-BXD, VT-BXF, VT-BXG, VT-BXL UNABLE REQD NAV PERF-RNP message will be displayed if there is a divergence between IRU-L and IRU-R inertial altitude, or between IRS-L and IRS-R inertial vertical speed, when the aircraft is on an RNP-AR approach leg.	Refer to UNABLE REQD NAV PERF-RNP non-normal checklist in the QRH. Note: When on a procedure or airway without an RNP alerting requirement, the FMC Navigation Check supplementary procedure in SP11 can be used to verify position. VT-BXD, VT-BXF, VT-BXG, VT-BXL If a UNABLE REQD NAV PERF-RNP is shown during the RNP-AR approach, whether the lateral or vertical RNP are exceeded or not, do the Go-Around and Missed Approach Procedure unless suitable visual reference is established and maintained.
USING RSV FUEL	FMC fuel at the destination is predicted to be less than the entered RESERVES fuel. Scratchpad message shows for Active and Mod Flight Plan. Illuminates the FMC P/RST Light for Active and Mod Flight Plan. Message displayed on Engine display for the Active Flight Plan only.	Refer to USING RSV FUEL non-normal checklist in the QRH. The Engine Display message will remain until the condition is no longer valid.
VERIFY GW AND FUEL	Fuel data becomes invalid, PERF INIT fuel value is replaced with dashes. FMC uses last valid fuel quantity for performance predictions until manual entry is made. Shows if 30 minutes have elapsed since last manual entry. Does not show in descent with Vref selected.	Enter fuel weight on PERF INIT page 1/2. Periodic update of fuel weight is required to keep gross weight value current.
VERIFY POS: FMC-FMC	Position information is contradictory.	Refer to FMC Navigation Check Supplementary Procedure.
VERIFY POS: FMC-GPS	Position information is contradictory.	Refer to FMC Navigation Check Supplementary Procedure.
VERIFY POS: FMC-RADIO	Position information is contradictory.	Refer to FMC Navigation Check Supplementary Procedure.
VERIFY POS: IRS-FMC	Position information is contradictory.	Refer to FMC Navigation Check Supplementary Procedure.
VERIFY POS: IRS-IRS	Position information is contradictory.	Refer to FMC Navigation Check Supplementary Procedure.
VERIFY POS: IRS-RADIO	Position information is contradictory.	Refer to FMC Navigation Check Supplementary Procedure.
VERIFY POSITION (on ground)	Position information is contradictory.	Clear message. Check accuracy of manually entered data. Crosscheck IRS, GPS and FMC positions. Manually re-align both IRS’s if needed.
VERIFY RNP	Underlying RNP value is less than manually entered value.	Enter appropriate RNP.
VERIFY TAKEOFF SPEEDS	A PERF INIT change has been made after takeoff speeds were specified.	On TAKEOFF REF page 1, accept previous V speeds, or reject previous V speeds and enter new V speeds.
VERIFY TAKEOFF THRUST	With the Takeoff Thrust Auto Selection option enabled, the system determines that the selected takeoff thrust setting is not compatible with the engine thrust rating configuration.	Clear the message. Manually change takeoff thrust setting, or accept uplink of different thrust setting.
VERIFY VERT RNP	During an active descent with navigation performance scales enabled, a manually entered vertical RNP is greater than the default vertical RNP.	Clear CDU message. Enter appropriate vertical RNP.
VNAV DISCONNECT	The criteria for VNAV engagement is not satisfied (VNAV disengages). On approach, with VNAV engaged, the FCC has switched to LVL CHG.	Manually control the vertical path.
VNAV INVALID-PERF	If the exception affects both the MOD and the ACT flight plan, the Cost Index (CI) will be replaced with box prompts on the PERF INIT page and the message will result. LNAV is still valid and can navigate the airplane laterally but VNAV will disconnect. Reference section 11.32 for further Software Exception Logic.	Pilot should reenter the CI using either the previous CI displayed or enter a new CI. Reengage VNAV when change has been EXECuted.

FMC Entry Error Messages

FMC Entry Error Messages indicate incorrect entries made in the CDU scratchpad. These messages:

Displayed in the CDU scratchpad.
Illuminate the message (MSG) light on the CDU where the error occurred.
Temporarily replace the existing scratchpad data.

To remove the message:

Press the CLR key to restore the previously entered data.
Enter new data to replace both the error message and the previous entry.

ENTRY ERROR MESSAGE	CAUSE	CORRECTIVE ACTION
ALT CONSTRAINT XXXXX (waypoint identifier)	A flight plan modification has caused an altitude conflict with a waypoint that has an altitude constraint.	Clear the message and revise the entry.
DATA BASE FULL	Entry attempted into a supplemental or temporary navigation database category which is full.	Go to the NAV DATA pages and delete unneeded waypoints, navaids, or airports from the appropriate database and re–attempt entry.
DUPLICATE FLIGHT PLAN ID	The entry attempted is a duplicate of an existing supplemental flight plan name.	Clear the message and select a unique flight plan name.
INVALID DELETE	DEL key operation was attempted for a data line to which it was not applicable.	Clear the message and select the proper line after the DEL key is pressed.
INVALID ENTRY	Attempted data entry has incorrect format, range, etc. for the selected data line. Entered RTA waypoint is not in the flight plan.	Clear the message and scratchpad entry, and repeat the entry with the correct data.
INVALID QUAD	Attempted HOLD page QUAD entry has incorrect format or range.	Clear the message and revise the QUAD entry.
NO OFFSET AT LEG XXXXX (waypoint)	Attempted entry of a lateral offset start or end waypoint XXXXXX that is not offsetable (lateral offset as installed).	Clear the message and amend the route.
NOT IN DATA BASE	FMC does not contain the required data for the entered identifier.	Clear the message and check data entry, or enter the required information into the supplemental or temporary navigation database via the NAV DATA pages.
NOT IN FLIGHT PLAN	RTA waypoint or lateral offset (as installed) start/end waypoint entry is not in the active flight plan.	Clear the message and amend the entry.
ROUTE FULL	Entry of more than maximum allowed number of waypoints or holding patterns attempted.	Clear the message and review existing and desired waypoints and holding patterns for possible deletion.
SUPP RTE DATA BASE FULL	Attempted save of the 11th supplemental flight plan.	Clear the message, delete unneeded supplemental flight plans and re–attempt entry.

FMC Advisory Messages

FMC Advisory Messages provide information about FMC status. These messages:

Displayed in the CDU scratchpad.
Illuminate the message (MSG) lights on both CDUs.

To clear the message:

Use the CLR key or correct the condition.
The message temporarily disappears from the scratchpad during manual data entry but reappears if the data is removed without addressing the issue.

ADVISORY MESSAGE	CAUSE	CORRECTIVE ACTION
ABOVE MAX CERT ALT	The airplane is above its maximum certified altitude.	Descend to an altitude below the maximum certified altitude.
APPRCH VREF NOT SELECTED	Airplane has transitioned into approach environment and Vref has not been selected on APPROACH REF page.	Select Vref on APPROACH REF page.
ARR N/A FOR RUNWAY	Runway or approach does not match the selected arrival procedure.	Go to the ARRIVALS page and modify selection.
BUFFET ALERT (Only appears if flaps are retracted)	Current conditions result in a maneuver margin less than specified.	Bring the airplane back within the operating envelope.
CHECK FMC FUEL QUANTITY	The FMC has detected an unexpected drop in the fuel quantity.	Check the fuel quantity indications for correctness.
DRAG REQUIRED	Airspeed is 10 kts or more above FMC target speed or within 5 kts of Vmo/Vmmo.	Use speedbrakes, trim or reduced thrust, as required, to bring the airplane within 5 kts of FMC target speed.
ENTER EO CRZ SPD AND ALT	Engine-out operation has been terminated and no cruise speed or altitude has been entered.	Enter cruise speed and altitude on cruise page.
FMC APP MODE UNAVAIL–GP	The approach selected in the FMC does not have a specified glide path angle for final approach. The FMC approach mode cannot be used for this approach.	Select an alternate approach. Clear the message.
FMC APP MODE UNAVAIL–QFE	An approach that utilizes FMC generated glide path is in the flight plan, but QFE is selected on the FMC.	Select QNH as the landing altimeter reference on the APPROACH REF page. Clear the message.
INVALID INACTIVE PLAN	An exception has occurred in the INACTIVE plan prior to execution and it has been deleted as a result.	Reenter a new version of the INACTIVE plan.
INVALID MOD PLAN	An exception has occurred in the MOD plan and it has been deleted as a result.	Reenter a new version of the MOD plan.
INVALID OFFSET	Desired offset does not meet FMC offset criteria.	Clear the message and amend the entry.
KEY/FUNCTION INOP	A mode key is pressed for which an FMC function has not been implemented or has not been enabled. (FANS MCDU only)	Clear the message or select another CDU page for display.
LOC CAP ACTIVE	The airplane is approaching its turn onto the LOC or GLS course and will maintain an intercept heading.	Clear the message manually, or wait for the AFDS to signal reset status to the FMC.
LOC CAP CANCELLED U14 Removes [LOC CAP CANCELLED]	Flight plan modifications or the airplane condition did not facilitate localizer capture.	Clear the message manually, or wait for the AFDS to reset to LOC CAP ACTIVE
MAX ALT FLXXX (flight level value)	Altitude entry on any page is above the maximum altitude for current selected performance margins.	Clear the message or amend the data entry.
MAX MACH .XXX/MIN MACH .XXX OR MAX CAS .XXX/MIN CAS .XXX	FMC target speed is greater than the maximum or less than the minimum buffet speed for the entered cruise or step climb altitude.	Change the target speed to within the message limits or enter a lower altitude.
NO DES PATH AFTER XXXXX (waypoint)	FMC is unable to construct a PATH DES that satisfies all altitude restrictions after XXXXX.	Modify speed or altitude restrictions on the RTE LEGS pages.
NOT ON INTERCEPT HEADING	Airplane is not within the LNAV capture criteria for the active leg (LNAV disengages). If the LNAV button is pressed and the airplane is not within the capture criteria. (LNAV will not engage)	Manually place the airplane on an intercept heading and reengage LNAV.
OFFSET DELETED	The entered start waypoint has been deleted from the flight plan. (lateral offset as installed)	Clear the message and amend the route.
OFST ENDS ABEAM XXXXXX	An invalid offset leg exists between the end waypoint (XXXXXX) and the start of offset or no end waypoint exists.	Clear the message and amend the route.
PERF DEFAULTS DELETED	Performance database has been automatically deleted due to conflict with performance database limits.	Contact maintenance personnel.
POS SHIFT OVER 50NM	A viable position shift is currently selected that will result in an FMC position shift in excess of 50nm when executed.	Clear the message.
PROGRAM PIN ERROR	FMC connector wiring is incorrect.	System unusable; advise maintenance personnel. The CLR key will not clear the message.
PROGRAM PIN NOT IN DB	FMC connector wiring or performance database is incorrect.	Advise Maintenance Personnel
RESET MCP ALT	Normal FMC operation would require flying away from MCP altitude.	Select a MCP altitude value in the proper direction (higher for climb, lower for descent).
RESET MCP APP MODE	A change in the expected approach is made with an FCC approach mode armed or engaged.	Clear and rearm FCC approach mode. Clear the message.
RUNWAY N/A FOR SID	The selected runway is not applicable to the selected departure procedure.	Clear the message and check selections on the DEPARTURES page. Modify as required.
SELECT ACTIVE WPT/LEG	Power–up restart or insertion of a different flight plan while airborne.	EXECute a direct–to or leg intercept to tell the FMC which leg of the route is active.
STEEP DESCENT AFTER XXXXXX	An excessive vertical discontinuity exists after point XXXXXX.	Check routing.
TAI ON ABOVE 10°C	Airplane is operating with anti–icing with TAT above +10°C.	Clear the message and check the use of anti–icing for engines and/or wings.
UNABLE CRZ ALT	FMC predicts that no cruise time is possible at the entered CRZ ALT.	Clear the message and review the CRZ ALT selection.
UNABLE MACH .XXX	The entered cruise Mach is unattainable based on present gross weight.	Select a smaller Mach number or wait until gross weight is reduced sufficiently.
UNABLE TO OFFSET	A valid offset cannot be constructed due to geometric limitations.	Clear the message and amend the route.
V SPEEDS UNAVAILABLE	FMC cannot compute V speeds (as installed) due to unreasonable inputs on the RTE, PERF INIT, or TAKEOFF REF pages.	Correct inputs that affect V speed computation.
VERIFY RNP VALUE	When entering an RNP the underlying RNP value is smaller than the manually entered value or the ANP is greater than the manually entered RNP.	Change or delete the manually entered RNP.
VERIFY VERT RNP VALUE	With navigation performance scales enabled, a manually entered vertical RNP is greater than the default vertical RNP or manually entered vertical RNP is less that vertical ANP.	Clear the message. Change or delete the manually entered RNP.
XXXX (airport identifier)	A REF AIRPORT is entered on the POS INIT page and no entry of ORIGIN yet appears on RTE page 1.	Enter the airport identifier on the ORIGIN data line.
XXXXX (MCP altitude value)	With the CRZ page displayed, resetting the AFDS MCP altitude to a value different from the CRZ ALT causes the value to appear in the scratchpad.	Enter the MCP altitude value on the appropriate target altitude data line.

FMC Data Link Messages

These messages relate to FMC data link message status. FMC data link alerting and advisory messages function the same as the alerting and advisory messages described above.

FMC Data Link Alerting Messages

ALERTING MESSAGE	CAUSE	CORRECTIVE ACTION
ALTN DEST UPLINK	An FMC alternate destinations uplink message has been loaded on the ALTERNATE DESTS page, and is ready for flight crew review. (Alternate destinations as installed)	Review the alternate destinations uplink.
CRZ WIND UPLINK LOADING	An FMC cruise wind uplink message is loading (after LOAD selected on the RTE DATA page).	Wait for load to complete.
CRZ WIND UPLINK READY	Receipt of an ACARS uplink that contains cruise wind data, and the cruise wind data LOAD prompt is displayed on the RTE 1 or 2 DATA page.	Select RTE DATA page, LOAD cruise wind, and execute or ERASE.
CRZ WIND XXXXX (cruise altitude) UPLINK	An FMC cruise wind uplink message has been loaded on the RTE DATA page, and is ready for flight crew review.	Review the cruise wind uplink, and execute or ERASE.
DATALINK CONFIG INVALID	Validity check of the FMC datalink configuration file has failed.	Contact maintenance personnel.
DESCENT FORECASTS UPLINK	An FMC descent forecasts uplink message has been loaded on the DESCENT FORECASTS page, and is ready for flight crew review.	Review the descent forecasts uplink, and execute or ERASE.
FORECASTS UPLINK READY	An FMC descent forecasts uplink message has been received and is available for loading on the DESCENT FORECASTS page.	Select DESCENT FORECASTS page, LOAD descent forecasts winds, and execute or ERASE.
INVALID TAKEOFF XXX/YYY (runway or runway/intersection identifier)	Runway (RTE page) or runway/intersection (TAKEOFF REF page) has been entered that matches runway takeoff data in FMC memory. However, the airplane is performance limited for the selected runway.	Clear the message. Enter correct takeoff data, request new takeoff data uplink, or enter new runway or runway/intersection identifier.
NAV DATA LOADING	An FMC supplemental navigation data uplink message has been received and is loading.	Wait for load to complete.
NAV DATA UPLINK	An FMC supplemental navigation data uplink message has been loaded on the SUPP NAV DATA page, and is ready for flight crew review.	Review the supplemental navigation data uplink, and execute or ERASE.
PARTIAL ALTN DEST UPLINK	An FMC alternate destinations uplink message has been loaded on the ALTERNATE DESTS page, but errors were encountered during the loading process. (Alternate destinations as installed)	Review the alternate destinations uplink, and execute or ERASE.
PARTIAL FORECASTS UPLINK	An FMC descent forecasts uplink message has been loaded on the DESCENT FORECASTS page, but errors were encountered during the loading process.	Review the descent forecasts uplink, and execute or ERASE.
PARTIAL LIMITS UPLINK	An FMC performance limits uplink message has been loaded on the PERF LIMITS page, but errors were encountered during the loading process.	Review the performance limits uplink, and execute or ERASE.
PARTIAL NAV DATA UPLINK	An FMC supplemental navigation data uplink message has been loaded on the SUPP NAV DATA page, but errors were encountered during the loading process.	Review the supplemental navigation data uplink, and execute or ERASE.
PARTIAL PERF INIT UPLINK	An FMC performance initialization uplink message has been loaded on the PERF INIT page, but errors were encountered during the loading process.	Review the performance initialization uplink, and execute or ERASE.
PARTIAL ROUTE X UPLINK	Receipt of an ACARS non-ATC uplink message that contains route data. The route data has been partially loaded into the active/inactive RTE 1 or 2 flight plan buffer due to errors.	Review the route uplink, and execute or ERASE.
PERF INIT UPLINK	An FMC performance initialization uplink message has been loaded on the PERF INIT page, and is ready for flight crew review.	Review the performance initialization uplink, and execute or ERASE.
PERF INIT UPLINK READY	An FMC performance initialization uplink message has been received and is available for loading on the PERF INIT page.	Select PERF INIT page, LOAD performance initialization data, and execute or ERASE.
PERF LIMITS UPLINK	An FMC performance limits uplink message has been loaded on the PERF LIMITS page, and is ready for flight crew review.	Review the performance limits uplink, and execute or ERASE.
PERF LIMITS UPLINK READY	An FMC performance limits uplink message has been received and is available for loading on the PERF LIMITS page.	Select PERF LIMITS page, LOAD performance limits, and execute or ERASE.
RESEND MESSAGE	An FMC downlink message was attempted, but the FMC was unable to deliver the message to the ACARS MU.	Re–send the downlink message.
ROUTE X DATA UPLINK	An FMC route uplink message has been loaded into the active/inactive RTE 1 or 2 flight plan buffer, and is ready for flight crew review.	Review the route uplink, and execute or ERASE.
ROUTE X UPLINK LOADING	Receipt of an ACARS non-ATC uplink message that contains route data. The route data is currently being loaded into the active or inactive RTE 1 or 2 flight plan.	Wait for load to complete.
ROUTE X UPLINK READY	Receipt of an ACARS non-ATC uplink that contains route data, and the route data LOAD prompts are displayed on the active/inactive RTE 1 or 2 and active/inactive LEGS 1 or 2 pages.	Select the active/inactive RTE 1 or 2 page or active/inactive LEGS 1 or 2 page, LOAD route, and execute or ERASE.
RTA DATA UPLINK	An FMC RTA uplink message has been loaded on the RTA PROGRESS page, and is ready for flight crew review.	Review the RTA uplink, and execute or ERASE.
RTA UPLINK READY	An FMC RTA uplink message is has been received and is available for loading on the RTA PROGRESS page.	Select RTA PROGRESS page, LOAD RTA data, and execute or ERASE.
TAKEOFF DATA LOADED	Uplink takeoff data matching Runway (RTE page) or runway/intersection (TAKEOFF REF page) has been loaded on the TAKEOFF REF page, and is ready for flight crew review.	Select TAKEOFF REF page, accept or reject takeoff data.
TAKEOFF DATA UPLINK	An FMC takeoff data uplink message containing one or more sets of runway takeoff data has been received and loaded in FMC memory.	Enter appropriate runway (RTE page) or runway/intersection (TAKEOFF REF page) to access runway takeoff data.

FMC Data Link Advisory Messages

ADVISORY MESSAGE	CAUSE	CORRECTIVE ACTION
INVALID ALTN DEST UPLINK	An FMC alternate destinations uplink message was received, but was rejected due to errors.	Clear the message.
INVALID CRZ WIND UPLINK	An FMC cruise wind uplink message was received, but was rejected due to errors.	Clear the message.
INVALID FORECASTS UPLINK	An FMC descent forecasts uplink message was received, but was rejected due to errors.	Clear the message.
INVALID LIMITS UPLINK	An FMC performance limits uplink message was received, but was rejected due to errors.	Clear the message.
INVALID NAV DATA UPLINK	An FMC supplemental navigation data uplink message was received, but was rejected due to errors.	Clear the message.
INVALID PERF INIT UPLINK	An FMC performance initialization uplink message was received, but was rejected due to errors.	Clear the message.
INVALID ROUTE or ROUTE X UPLINK	An FMC route uplink message was received, but was rejected due to errors.	Clear the message.
INVALID RTA UPLINK	An FMC RTA uplink message was received, but was rejected due to errors.	Clear the message.
INVALID TAKEOFF UPLINK	An FMC takeoff data uplink message was received, but was rejected due to errors.	Clear the message.

ATC Data Link Messages

These messages relate to ATC data link message status. ATC data link alerting and advisory messages function the same as the alerting and advisory messages described above.

ATC Data Link Alerting Messages

ALERTING MESSAGE	CAUSE	CORRECTIVE ACTION
ATC DATABASE INVALID (U14.0 and above)	ATC data base is not available/loaded at power up on the ground.	Clear CDU Message
ATC COMM ESTABLISHED	Active ATC connection established.	Clear message.
ATC COMM TERMINATED	ATC connection terminated without transfer to another service station.	Clear message.
ATC MESSAGE	Receipt of valid ATC datalink message.	Clear message and display the received ATC uplink.
ATC REPORT LIST FULL	ATC REPORT buffer is full.	Clear message and send or delete reports listed on the ATC REPORT page.
ATC ROUTE X DATA UPLINK	Receipt of am ATC ACARS uplink message containing route data. The route data has been loaded into the active RTE 1 or 2 flight plan buffer.	Review the route uplink, and execute or ERASE.
ATC ROUTE X UPLINK LOADING	Receipt of an ATC ACARS uplink message containing route data. The route data is currently being loaded into the active RTE 1 or 2 FMC flight plan buffer.	Clear message.
ATC ROUTE X UPLINK READY	Receipt of an ATC ACARS uplink that contains route data, and the route data LOAD prompts are displayed on the active/inactive RTE 1 or 2 and active/inactive LEGS 1 or 2 pages.	Select the active/inactive RTE 1 or 2 page or active/inactive LEGS 1 or 2 page, LOAD route, and execute or ERASE.
ATC RTA DATA UPLINK	Receipt of an ATC ACARS uplink message containing RTA data. The RTA data is currently being loaded into the active RTE 1 or 2 flight plan.	Review the RTA uplink, and execute or ERASE.
CLEARANCE CONDITION MET (U14.0 and above)	The clearance being monitored is met.	Perform clearance instruction
CLEARANCE COND NOT MET (U14.0 and above)	The clearance being monitored is executed prior satisfying clearance.	Review clearance being monitored, select “MONITOR” on ATC INDEX page. Comply with ATC clearance
CLR COND NOT IN RTE (U14.0 and above)	When the waypoint in the clearance being monitored is deleted from the active route or a clearance is accepted and the waypoint is not in the active route..	Review clearance being monitored, select “MONITOR” on ATC INDEX page. Comply with ATC clearance
ATN DATA BASE INVALID (U14.0 and above)	ATN Data Base is not available/loaded and FANS-2 option is enabled	Load ATN Data Base
ATC TIMEOUT-RESEND (U14.0 and above)	CPDLC downlink has been sent and the required response has not been received	Resend message
DATALINK LOST	Datalink connectivity has been lost	Notify ATC of the loss of FANS datalink connectivity.
INVALID ATC (ROUTE or ROUTE X) UPLINK	ATC uplink received by FMC contains errors.	Clear message.
INVALID ATC UPLINK	ATC uplink received by FMC contains errors.	Clear message.
MESSAGE LIMIT EXCEEDED	Crew attempts to select more than five message elements for inclusion in downlink message.	Clear message.
PARTIAL ATC ROUTE X UPLINK	Receipt of an ATC ACARS uplink message containing route data which passed syntax error checks, but contained errors in the data, and part of the active RTE 1 or 2 flight plan data has been loaded.	Review the route uplink, and execute or ERASE.
PARTIAL CLEARANCE LOADED	FMC able to load only a portion of data.	Clear message and reject uplinked clearance.
RE–LOGON TO ATC COMM	No response to logon message after 10 minutes.	Clear message and re-send logon message.
RESPOND TO ATC UPLINKS	ATC uplink pending storage full.	Clear message and respond to open uplinks.
UNABLE TO LOAD CLEARANCE	FMC unable to load any data from uplink.	Clear message and reject uplinked clearance.

Navlink ACARS Messages

Navlink ACARS Advisory Messages

Advisories are shown on the CDU next to L6 and R6. They signal the crew that either a condition requires attention or that a function is available. Typically a crew action extinguishes the advisory.

ACTIVE ADVISORY	CAUSE	CORRECTIVE ACTION
CONFIG	Airline ID or the Registration Number is not available to the CMU-900.	Advise maintenance.
BAD ACTYPE	Improper aircraft type loaded.	Advise maintenance.
APM ICAO	Aircraft Personality Mode (APM) status is INDETERMINATE because of an (ICAO) address conflict between the APM and the transponder broadcast.	Advise maintenance.
SELCAL	Voice go–ahead uplink message received.	Selected SELCAL page or select voice mode.
APM WARN	APM status is FAIL or ABSENT.	Advise maintenance.
CHIMES	A chimes suppression event has occurred. When selected, this advisory causes the CHIMES SUPPRESSED page to show.	This advisory clears when it is selected. The CHIMES advisory is then disabled until the CMU-900 has been restarted (a power cycle has occurred).

INACTIVE ADVISORY	CAUSE	MESSAGE CLEARED
LINK TEST SUCCESSFUL	Successful data link test of the communication medium (VHF, SATCOM, or HF) has been completed.	Message clears after ten seconds.
UTC UPDATED	A UTC Clock Update message has been received from the ground.	Message clears after ten seconds.
VHF VOICE MODE	The CMU-900 system is in VHF Voice Mode.	Shows for the duration that the system remains in VHF Voice Mode, and is cleared when the system returns to Data Mode.
NO COMM	Neither VHF, SATCOM, nor HF media have established a link with the ground over which a message may be sent.	Advisory shows for the duration that the system remains without a link, and is cleared when the system establishes a link.
VHF IN PROG	The system has sent a downlink message via VHF and has not yet received an acknowledgment from the service provider.	Advisory clears when all VHF messages have been acknowledged, or the VHF link fails and VHF goes to NO COMM.
SATCOM IN PROG	The system has sent a downlink message via SATCOM and has not yet received an acknowledgment from the service provider.	Advisory clears when all SATCOM messages have been acknowledged or the SATCOM link fails.
HF IN PROG	The system has sent a downlink message via HF and has not yet received an acknowledgment from the service provider.	Advisory clears when all HF messages have been acknowledged or the HF link fails.

Scratch Pad Messages

CDU SCRATCHPAD	CAUSE	CORRECTIVE ACTION
FORMAT ERROR	Shows when a line select key associated with manual entry is selected and the scratch pad data does not pass format or range checking.	Reformat manual entry.
BUTTON PUSH IGNORED	Shows when a line select key that has no assigned function on the display page is selected.	Select correct line select key.
NOT ALLOWED	Shows when a line select key associated with manual entry is selected but the scratch pad is empty.	Enter appropriate data in scratch pad if applicable.