AIM

4/3/14

1−1−26

Navigation Aids

such as “GPS RWY 24” for the VOR or GPS

RWY 24.

1.

For flight planning purposes, TSO-C129()

and TSO-C196() equipped users (GPS users) whose

navigation systems have fault detection and

exclusion (FDE) capability, who perform a preflight

RAIM prediction at the airport where the RNAV

(GPS) approach will be flown, and have proper

knowledge and any required training and/or approval

to conduct a GPS-based IAP, may file based on a

GPS-based IAP at either the destination or the

alternate airport, but not at both locations. At the

alternate airport, pilots may plan for applicable

alternate airport weather minimums using:

(a)

 Lateral navigation (LNAV) or circling

minimum descent altitude (MDA);

(b)

LNAV/vertical navigation (LNAV/

VNAV) DA, if equipped with and using approved

barometric vertical navigation (baro-VNAV) equip-

ment;

(c)

RNP 0.3 DA on an RNAV (RNP) IAP, if

they are specifically authorized users using approved

baro-VNAV equipment and the pilot has verified

required navigation performance (RNP) availability

through an approved prediction program.

2.

If the above conditions cannot be met, any

required alternate airport 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.

h. GPS NOTAMs/Aeronautical Information

1.

GPS satellite outages are issued as GPS

NOTAMs both domestically and internationally.

However, the effect of an outage on the intended

operation cannot be determined unless the pilot has a

RAIM availability prediction program which allows

excluding a satellite which is predicted to be out of

service based on the NOTAM information.

2.

The term UNRELIABLE is used in conjunc-

tion with GPS NOTAMs. The term UNRELIABLE is

an advisory to pilots indicating the expected level of

service may not be available. UNRELIABLE does

not mean there is a problem with GPS signal integrity.

If GPS service is available, pilots may continue

operations. If the LNAV or LNAV/VNAV service is

available, pilots may use the displayed level of

service to fly the approach. GPS operation may be

NOTAMed UNRELIABLE due to testing or

anomalies. (Pilots are encouraged to report GPS

anomalies, including degraded operation and/or loss

of service, as soon as possible, reference paragraph

1−1−14.)  Air Traffic Control will advise pilots

requesting a GPS or RNAV (GPS) approach of GPS

UNRELIABLE for:

(a)

NOTAMs not contained in the ATIS

broadcast.

(b)

Pilot reports of GPS anomalies received

within the preceding 15 minutes.

3.

Civilian pilots may obtain GPS RAIM

availability information for nonprecision approach

procedures by specifically requesting GPS aeronaut-

ical information from a Flight Service Station during

preflight briefings. GPS RAIM aeronautical informa-

tion can be obtained for a period of 3 hours (for

example, if you are scheduled to arrive at 1215 hours,

then the GPS RAIM information is available from

1100 to 1400 hours) or a 24 hour time frame at a

particular airport. FAA briefers will provide RAIM

information for a period of 1 hour before to 1 hour

after the ETA hour, unless a specific time frame is

requested by the pilot. If flying a published GPS

departure, a RAIM prediction should also be

requested for the departure airport.

4.

The military provides airfield specific GPS

RAIM NOTAMs for nonprecision approach proced-

ures at military airfields. The RAIM outages are

issued as M−series NOTAMs and may be obtained for

up to 24 hours from the time of request.

5.

Receiver manufacturers and/or database

suppliers may supply “NOTAM” type information

concerning database errors. Pilots should check these

sources, when available, to ensure that they have the

most current information concerning their electronic

database.

i. Receiver Autonomous Integrity Monitoring

(RAIM)

1.

RAIM outages may occur due to an

insufficient number of satellites or due to unsuitable

satellite geometry which causes the error in the

position solution to become too large. Loss of satellite

reception and RAIM warnings may occur due to

aircraft dynamics (changes in pitch or bank angle).

Antenna location on the aircraft, satellite position

relative to the horizon, and aircraft attitude may affect