Federal Aviation Administration (FAA) commissionsthe Wide AreaAugmentation System (WAAS)

Ref: http://www1.faa.gov/ntap/NTAP03JUL10/GEN03003.HTM

Wide Area Augmentation System (WAAS) Commissioning Information, WAAS
and GPS NOTAM Changes, and Removal of NA from select RNAV (GPS) and
GPS Approach Charts

a. Introduction. On July 10, 2003, the Federal Aviation Administration
(FAA) will commission the Wide Area Augmentation System (WAAS). WAAS
may be used for aviation navigation in both instrument flight rules
(IFR) and visual flight rules (VFR) operations. WAAS improves the
availability, accuracy, and integrity of the NavSTAR Global Positioning
System (GPS) standard positioning service, enabling WAAS avionics to be
used for all phases of flight, including approaches with vertical
guidance (APVs). Appropriately certified and installed WAAS avionics
may be used for all phases of flight - departure, including Standard
Instrument Departures (SIDs); en route, including area navigation
(RNAV) and airways navigation; arrival and in the terminal area,
including Standard Terminal Arrival Routes (STARs); and for instrument
approaches. Authorized instrument approaches include the LNAV and
LNAV/VNAV minima lines on RNAV (GPS) and GPS approach charts, as well
as the minima on conventional approach charts with "or GPS" in the
title. Additionally, a new type of APV minima titled LPV will be
published on RNAV (GPS) approach charts beginning in the near future.
Detailed information on the various approaches that can be flown using
WAAS is provided in the Aeronautical Information Manual (AIM)
(paragraphs 1-1-22 and 5-4-5). Pilots will find additional information
on navigation equipment capability in the RNAV (GPS) chart legend in
the front of each volume of instrument approaches published by the FAA.

NOTE- WAAS avionics must be certified in accordance with Technical
Standard Order (TSO) C-145A, Airborne Navigation Sensors Using the
(GPS) Augmented by the Wide Area Augmentation System (WAAS); or
TSO-146A, 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 Navigation Sensors, or AC 20-138A,
Airworthiness Approval of Global Positioning System (GPS) Navigation
Equipment for Use as a VFR and IFR Navigation System.

b. Operational Guidance: Removal of NA and the new negative W symbol
(). Due to initial system limitations, there are certain restrictions
on WAAS operations.

1. Pilots may plan to use any instrument approach authorized for
use with WAAS avionics at a required alternate. However, when using
WAAS at an alternate airport, flight planning must be based on
flying the RNAV (GPS) LNAV minima line, or minima on a GPS approach
procedure, or conventional approach procedure with "or GPS" in the
title. Code of Federal Regulation (CFR) Part 91 nonprecision
weather requirements must be used for planning. Upon arrival at an
alternate, when the WAAS navigation system indicates that LNAV/VNAV
or LPV service is available, then vertical guidance may be used to
complete the approach using the displayed level of service.

2. Coincident with WAAS commissioning, the FAA will begin removing
the NA (Alternate Minimums Not Authorized) symbol from select RNAV
(GPS) and GPS approach procedures so they may be used by approach
approved WAAS receivers at alternate airports. Some approach
procedures will still require the NA for other reasons, such as no
weather reporting, so it cannot be removed from all procedures.
Since every procedure must be individually evaluated, removal of
the NA from RNAV (GPS) and GPS procedures will take some time.

NOTE- This does not change the existing alternate airport requirements
for users of GPS TSO-C129/129A, Airborne Supplemental Navigation
Equipment Using the Global Positioning System (GPS), receivers. For TSO
C-129/129A users, any required alternate airport must still 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.

3. At locations where outages of WAAS vertical guidance may occur
daily due to initial system limitations, a negative W symbol ()
will be placed on RNAV (GPS) approach charts. Many of these outages
will be very short in duration, but may result in the disruption of
the vertical portion of the approach. The symbol indicates that
NOTAMs or Air Traffic advisories are not provided for outages which
occur in the WAAS LNAV/VNAV or LPV vertical service. Use LNAV
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 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. As the WAAS coverage is expanded, the will be removed.

c. WAAS and GPS Notice to Airman (NOTAM) Service. 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. WAAS NOTAMs.

(a) 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.

(b) 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.

(c) When the approach chart is annotated with the symbol,
site-specific WAAS UNRELIABLE NOTAMs or Air Traffic advisories
are not provided for outages in WAAS LNAV/VNAV and LPV vertical
service.

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.

2. GPS NOTAMs.

(a) GPS operation may be NOTAMed UNRELIABLE due to testing or
anomalies.

(b) Air Traffic Control will advise pilots requesting a GPS or
RNAV (GPS) approach of GPS UNRELIABLE for:

(1) NOTAMs not contained in the ATIS broadcast.

(2) Pilot reports of GPS anomalies received within the
preceding 15 minutes.

d. Additional Information.

1. Aircraft with IFR approved WAAS avionics can file /G.

2. 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.