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(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
CYAN MESSAGE (STATUS)
WHITE MESSAGE Require immediate crew attention. These messages are accompanied by flashing master warning, triple chime attenson with or without voice message or dedicated tone. Require immediate crew awareness and future crew action may be required in the form of alternate system selection or performance limitation. These message are accompanied by flashing master caution and a single chime. Indicate safe or normal system operation which require crew awareness, over and above the dark cockpit philosophy. Indicate minor failures or reduction in systems capability, which require no crew action.

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04/26/21

Message Overview:

Message Name:

VERTICAL NAVIGATION FLAG (Warning)

Identifier: 346OBS002
Effectivity: AIRCRAFT 20501 - 20999
System: Navigation
Associated CAS: None
System Description: 34-61-00
Schematic Diagram: 34-61-00
Wiring Diagram: 34-61-03
34-61-07

Message Description:

The red 'VNAV' warning flag indicates the vertical navigation is invalid.

  • Vertical navigation must be selected on the flight director system.
  • A loss of all data from the long range navigation system, most likely caused by the Flight Management System.
  • Troubleshooting using the MDC current fault page may help isolate the system, verify that power is available and check the data bus information.

01_vnv45_current_faults

Possible Causes:

  • Flight Management Computer 1 (FMC 1) (A4-FMC1)
  • Flight Management Computer 2 (FMC 2) (A4-FMC2)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Removal of the Flight Management Computer (FMC) AMM 34-61-01-000-801
Installation of the Flight Management Computer (FMC) AMM 34-61-01-400-801
Removal of the Control Display Unit (CDU) AMM 34-61-05-000-801
Installation of the Control Display Unit (CDU) AMM 34-61-05-400-801
Removal of the Input/Output Concentrator Unit (IOC) AMM 31-45-05-000-801
Installation of the Input/Output Concentrator Unit (IOC) AMM 31-45-05-400-801
Functional Test of the VHF Navigation Receiver AMM 34-51-01-720-801
Operational Test of the Global Positioning System AMM 34-55-00-710-801
Standard Practices - Wire Repair SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Perform the functional test of the VHF Navigation system.
  2. Perform the operational test of the GPS system.
  3. Do close out.

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