AIM

4/3/14

1−1−33

Navigation Aids

locations close to the edge of the coverage may have

a lower availability of vertical guidance.

c. General Requirements

1.

WAAS avionics must be certified in

accordance with Technical Standard Order (TSO)

TSO−C145a, Airborne Navigation Sensors Using the

(GPS) Augmented by the Wide Area Augmentation

System (WAAS); or TSO−C146a, Stand−Alone

Airborne Navigation Equipment Using the Global

Positioning System (GPS) Augmented by the Wide

Area Augmentation System (WAAS), and installed in

accordance with Advisory Circular (AC) 20−130A,

Airworthiness Approval of Navigation or Flight

Management Systems Integrating Multiple Naviga-

tion Sensors, or AC 20−138A, Airworthiness

Approval of Global Positioning System (GPS)

Navigation Equipment for Use as a VFR and IFR

Navigation System.

2.

GPS/WAAS operation must be conducted in

accordance with the FAA−approved aircraft flight

manual (AFM) and flight manual supplements. Flight

manual supplements will state the level of approach

procedure that the receiver supports. IFR approved

WAAS receivers support all GPS only operations as

long as lateral capability at the appropriate level is

functional. WAAS monitors both GPS and WAAS

satellites and provides integrity.

3.

GPS/WAAS equipment is inherently capable

of supporting oceanic and remote operations if the

operator obtains a fault detection and exclusion

(FDE) prediction program.

4.

Air carrier and commercial operators must

meet the appropriate provisions of their approved

operations specifications.

5.

Prior to GPS/WAAS IFR operation, the pilot

must review appropriate Notices to Airmen (NOT-

AMs) 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 UNRELIABLE is used in

conjunction with GPS and WAAS NOTAMs. The

term UNRELIABLE is an advisory to pilots

indicating the expected level of WAAS service

(LNAV/VNAV, LPV) may not be available;

e.g., !BOS BOS WAAS LPV AND LNAV/VNAV

MNM UNREL WEF 0305231700 

− 0305231815.

WAAS UNRELIABLE NOTAMs are predictive in

nature and published for flight planning purposes.

Upon commencing an approach at locations

NOTAMed WAAS UNRELIABLE, 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 may be required.

(1)

Area−wide WAAS UNAVAILABLE

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 UNAVAILABLE NOTAMs if not contained

in the ATIS broadcast.

(2)

Site−specific WAAS UNRELIABLE

NOTAMs indicate an expected level of service,

e.g., LNAV/VNAV 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 UNRELIABLE

NOTAMs.

(3)

When the approach chart is annotated

with the   symbol, site−specific WAAS UNRELI-
ABLE 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 UNAVAILABLE NOTAMs apply to all

airports in the WAAS UNAVAILABLE area designated in
the NOTAM, including approaches at airports where an
approach chart is annotated with the 

 symbol.

6.

GPS/WAAS was developed to be used within

SBAS GEO coverage (WAAS or other interoperable

system) without the need for other radio navigation

equipment appropriate to the route of flight to be

flown. Outside the SBAS coverage or in the event of

a WAAS failure, GPS/WAAS equipment reverts to