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Performance−Based Navigation (PBN) and Area Navigation (RNAV)

using TSO−C145/−C146 WAAS equipment. For

further WAAS guidance, see paragraph 1−1−18.

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-


(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.

3. This restriction does not apply to

TSO-C145() and TSO-C146() equipped users

(WAAS users). For further WAAS guidance, see

paragraph 1−1−18.

1−2−4. Pilots and Air Traffic Controllers

Recognizing Interference or Spoofing

a. Pilots need to maintain position awareness

while navigating. This awareness may be facilitated

by keeping relevant ground−based, legacy naviga-

tional aids tuned and available. By utilizing this

practice, situational awareness is promoted and

guards against significant pilot delay in recognizing

the onset  of GPS interference. Pilots may find

cross−checks of other airborne systems (for example,

DME/DME/IRU or VOR) useful to mitigate this

otherwise undetected hazard.


AIM Paragraph 1−1−17, Global Positioning System (GPS)

AIM Paragraph 1−1−18, Wide Area Augmentation System (WAAS)

b. During preflight planning, pilots should be

particularly alert for NOTAMs which could affect

navigation (GPS or WAAS) along their route of

flight, such as Department of Defense electronic

signal tests with GPS.


AIM Paragraph 1−1−17, Global Positioning System (GPS)

AIM Paragraph 1−1−18, Wide Area Augmentation System (WAAS)

c. If the pilot experiences interruptions while

navigating with GPS, the pilot and ATC may both

incur a higher workload. In the aircraft, the pilot may

need to change to a position determining method that

does not require GPS−derived signals (for example,

DME/DME/IRU or VOR). If transitioning to VOR

navigation, the pilot should refer to the current Chart

Supplement U.S. to identify airports with available

conventional approaches associated with the VOR

Minimum Operational Network (MON) program. If

the pilot’s aircraft is under ATC radar or multilatera-

tion surveillance, ATC may be able to provide radar

vectors out of the interference affected area or to an

alternate destination upon pilot request. An ADS−B

Out aircraft’s broadcast information may be incorrect

and should not be relied upon for surveillance when

interference or spoofing is suspected unless its

accuracy can be verified by independent means.

During the approach phase, a pilot might elect to

continue in visual conditions or may need to execute

the published missed approach. If the published

missed approach procedure is GPS−based, the pilot

will need alternate instructions. If the pilot were to

choose to continue in visual conditions, the pilot

could aid the controller by cancelling his/her IFR

flight plan and proceeding visually to the airport to

land. ATC would cancel the pilot’s IFR clearance and

issue a VFR squawk; freeing up the controller to

handle other aircraft.

d. The FAA requests that pilots notify ATC if they

experience interruptions to their GPS navigation or

surveillance. GPS interference or outages associated

with a known testing NOTAM should not be reported

to ATC unless the interference/outage affects the

pilot’s ability to navigate his/her aircraft.


AIM Paragraph 1−1−13, User Reports Requested on NAVAID or Global

Navigation Satellite System (GNSS) Performance or Interference.


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