5. Prior to GPS/WAAS IFR operation, the pilot must review appropriate Notices to Air Missions
(NOTAMs) and aeronautical information. This information is available on request from a Flight Service Station.
The FAA will provide NOTAMs to advise pilots of the status of the WAAS and level of service available.
(a) The term MAY NOT BE AVBL is used in conjunction with WAAS NOTAMs and indicates that due
to ionospheric conditions, lateral guidance may still be available when vertical guidance is unavailable. Under
certain conditions, both lateral and vertical guidance may be unavailable. This NOTAM language is an advisory
to pilots indicating the expected level of WAAS service (LNAV/VNAV, LPV, LP) may not be available.
EXAMPLE-
!FDC FDC NAV WAAS VNAV/LPV/LP MINIMA MAY NOT BE AVBL 1306111330-1306141930EST
or
!FDC FDC NAV WAAS VNAV/LPV MINIMA NOT AVBL, WAAS LP MINIMA MAY NOT BE AVBL
1306021200-1306031200EST

WAAS MAY NOT BE AVBL NOTAMs are predictive in nature and published for flight planning purposes.
Upon commencing an approach at locations NOTAMed WAAS MAY NOT BE AVBL, if the WAAS avionics
indicate LNAV/VNAV or LPV service is available, then vertical guidance may be used to complete the approach
using the displayed level of service. Should an outage occur during the approach, reversion to LNAV minima
or an alternate instrument approach procedure may be required. When GPS testing NOTAMS are published and
testing is actually occurring, Air Traffic Control will advise pilots requesting or cleared for a GPS or RNAV
(GPS) approach that GPS may not be available and request intentions. If pilots have reported GPS anomalies,
Air Traffic Control will request the pilot"s intentions and/or clear the pilot for an alternate approach, if available
and operational.
(b) WAAS area-wide NOTAMs are originated when WAAS assets are out of service and impact the
service area. Area-wide WAAS NOT AVAILABLE (AVBL) NOTAMs indicate loss or malfunction of the
WAAS system. In flight, Air Traffic Control will advise pilots requesting a GPS or RNAV (GPS) approach of
WAAS NOT AVBL NOTAMs if not contained in the ATIS broadcast.
EXAMPLE-
For unscheduled loss of signal or service, an example NOTAM is: !FDC FDC NAV WAAS NOT AVBL 1311160600-
1311191200EST.
For scheduled loss of signal or service, an example NOTAM is: !FDC FDC NAV WAAS NOT AVBL 13120410151312082000EST.

(c) Site-specific WAAS MAY NOT BE AVBL NOTAMs indicate an expected level of service; for
example, LNAV/VNAV, LP, or LPV may not be available. Pilots must request site-specific WAAS NOTAMs
during flight planning. In flight, Air Traffic Control will not advise pilots of WAAS MAY NOT BE AVBL
NOTAMs.
NOTE-
Though currently unavailable, the FAA is updating its prediction tool software to provide this site-service in the future.

(d) Most of North America has redundant coverage by two or more geostationary satellites. One
exception is the northern slope of Alaska. If there is a problem with the satellite providing coverage to this area,
a NOTAM similar to the following example will be issued:
EXAMPLE-
!FDC 4/3406 (PAZA A0173/14) ZAN NAV WAAS SIGNAL MAY NOT BE AVBL NORTH OF LINE FROM 7000N150000W
TO 6400N16400W. RMK WAAS USERS SHOULD CONFIRM RAIM AVAILABILITY FOR IFR OPERATIONS IN THIS
AREA. T-ROUTES IN THIS SECTOR NOT AVBL. ANY REQUIRED ALTERNATE AIRPORT IN THIS AREA MUST HAVE
AN APPROVED INSTRUMENT APPROACH PROCEDURE OTHER THAN GPS THAT IS ANTICIPATED TO BE
OPERATIONAL AND AVAILABLE AT THE ESTIMATED TIME OF ARRIVAL AND WHICH THE AIRCRAFT IS
EQUIPPED TO FLY. 1406030812-1406050812EST .

6. When GPS-testing NOTAMS are published and testing is actually occurring, Air Traffic Control will
advise pilots requesting or cleared for a GPS or RNAV (GPS) approach that GPS may not be available and request
intentions. If pilots have reported GPS anomalies, Air Traffic Control will request the pilot"s intentions and/or
clear the pilot for an alternate approach, if available and operational.

1-1-36

Navigation Aids