3/21/24
AIM
1311191200EST.
For scheduled loss of signal or service, an example NOTAM is: !FDC FDC NAV WAAS NOT AVBL 1312041015-
1312082000EST.
(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
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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.
EXAMPLE
−
Here is an example of a GPS testing NOTAM:
!GPS
06/001
ZAB NAV GPS (INCLUDING WAAS, GBAS, AND ADS-B) MAY NOT BE AVAILABLE WITHIN A 468NM
RADIUS CENTERED AT 330702N1062540W (TCS 093044) FL400-UNL DECREASING IN AREA WITH A DECREASE
IN ALTITUDE DEFINED AS: 425NM RADIUS AT FL250, 360NM RADIUS AT 10000FT, 354NM RADIUS AT 4000FT
AGL, 327NM RADIUS AT 50FT AGL. 1406070300-1406071200.
7.
When the approach chart is annotated with the
symbol, site
−
specific WAAS MAY NOT BE AVBL
NOTAMs or Air Traffic advisories are not provided for outages in WAAS LNAV/VNAV and LPV vertical
service. Vertical outages may occur daily at these locations due to being close to the edge of WAAS system
coverage. Use LNAV or circling minima for flight planning at these locations, whether as a destination or
alternate. For flight operations at these locations, when the WAAS avionics indicate that LNAV/VNAV or LPV
service is available, then the vertical guidance may be used to complete the approach using the displayed level
of service. Should an outage occur during the procedure, reversion to LNAV minima may be required.
NOTE
−
Area
−
wide WAAS NOT AVBL NOTAMs apply to all airports in the WAAS NOT AVBL area designated in the NOTAM,
including approaches at airports where an approach chart is annotated with the
symbol.
8.
GPS/WAAS was developed to be used within GEO coverage over North America without the need for
other radio navigation equipment appropriate to the route of flight to be flown. Outside the WAAS coverage or
in the event of a WAAS failure, GPS/WAAS equipment reverts to GPS
−
only operation and satisfies the
requirements for basic GPS equipment. (See paragraph 1
17 for these requirements).
9.
Unlike TSO
−
C129 avionics, which were certified as a supplement to other means of navigation, WAAS
avionics are evaluated without reliance on other navigation systems. As such, installation of WAAS avionics
does not require the aircraft to have other equipment appropriate to the route to be flown. (See paragraph
17 d for more information on equipment requirements.)
(a)
Pilots with WAAS receivers may flight plan to use any instrument approach procedure authorized for
use with their WAAS avionics as the planned approach at a required alternate, with the following restrictions.
Navigation Aids
1
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1
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