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AIM

10/12/17

1−1−32

Navigation Aids

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 opera-

tion and satisfies the requirements for basic GPS

equipment. (See paragraph 1−1−17 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 1−1−17 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. When using WAAS at

an alternate airport, flight planning must be based

on flying the RNAV (GPS) LNAV or circling 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

non−precision 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. The FAA has begun
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 individu-
ally evaluated, removal of the 

NA from RNAV

(GPS) and GPS procedures will take some time.

NOTE−

Properly trained and approved, as required, TSO-C145()

and TSO-C146() equipped users (WAAS users) with and

using approved baro-VNAV equipment  may plan for

LNAV/VNAV DA at an alternate airport. Specifically

authorized WAAS users with and using approved

baro-VNAV equipment may also plan for RNP 0.3 DA at the

alternate airport as long as the pilot has verified RNP

availability through an approved prediction program.

d. Flying Procedures with WAAS

1. WAAS receivers support all basic GPS

approach functions and provide additional capabilit-

ies. One of the major improvements is the ability to

generate glide path guidance, independent of ground

equipment or barometric aiding. This eliminates

several problems such as hot and cold temperature

effects, incorrect altimeter setting, or lack of a local

altimeter source. It also allows approach procedures

to be built without the cost of installing ground

stations at each airport or runway. Some approach

certified receivers may only generate a glide path

with performance similar to Baro−VNAV and are

only approved to fly the LNAV/VNAV line of minima

on the RNAV (GPS) approach charts. Receivers with

additional capability (including faster update rates

and smaller integrity limits) are approved to fly the

LPV line of minima. The lateral integrity changes

dramatically from the 0.3 NM (556 meter) limit for

GPS, LNAV, and LNAV/VNAV approach mode, to