If the NAV data mismatch occurs during flight, what is the recommended action?

• A. Continue as planned and ignore the mismatch.
• B. Turn off navigation systems.
• C. Reboot the FMS and try again.
• D. Verify navigation data status, consult maintenance, and update data as required.

Answer: (D)

The action tests how to respond to a NAV data mismatch during flight. A NAV data mismatch means the navigation database used by the aircraft’s systems does not align with the current, valid data. The correct approach is to verify the navigation data status, involve maintenance, and update the data as required. This ensures the FMS and onboard navigation reference the same up-to-date cycle, reducing the risk of incorrect routing or guidance. The typical flow is to check the data status in the system, confirm what cycle is loaded and whether any validation flags are present, then coordinate with maintenance to obtain and install the correct data set and recheck that the status becomes OK. After an update, the data should be verified again to confirm consistency and accuracy before continuing normally.

Choosing to ignore the mismatch or to take a quick reboot or turn-off of navigation systems does not fix the underlying data problem and can leave navigation guidance unreliable. Ignoring it could lead to navigation errors, while turning off navigation systems or rebooting without proper validation may compromise situational awareness and flight safety.