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A NANU is an advisory message to inform users of a change in the (1) _____ constellation. These messages are released 72 hours in advance for (2) _____.

  • A
    (1) GLONASS; (2) planned maintenance
  • B
    (1) GPS; (2) planned maintenance
  • C
    (1) GPS; (2) selected users
  • D
    (1) GLONASS; (2) selected users

Refer to figure.
Learning Objective 033.04.01.04.02: Define receiver autonomous integrity monitoring (RAIM), NOTAM and notice advisory to NavStar users (NANU) messages.


It is important before flight to check that there will be enough satellites visible for an accurate position at all stages of the flight but especially for the destination airfield and alternate.

This GNSS achievability can be verified by checking NOTAMs and the Notice Advisory to Navstar Users (NANU) messages which is issued jointly by the United States Coast Guard and the GPS Operations Centre in Colorado and provides updates on the GPS constellation.

NANUs are issued 72 hours (3 days) before any change of a GPS satellite regarding a change in orbit or a planned maintenance.

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