AIM

8/15/19

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9

Performance

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Based Navigation (PBN) and Area Navigation (RNAV)

unsatisfactory flight inspection, or a procedure that is
based upon a recently decommissioned NAVAID.

4.

Pilots may not substitute for the NAVAID (for example,

a VOR or NDB) providing lateral guidance for the final
approach segment. This restriction does not refer to
instrument approach procedures with “or GPS” in the title
when using GPS or WAAS. These allowances do not apply
to procedures that are identified as not authorized (NA)
without exception by a NOTAM, as other conditions may
still exist and result in a procedure not being available. For
example, these allowances do not apply to a procedure
associated with an expired or unsatisfactory flight
inspection, or is based upon a recently decommissioned
NAVAID.

5.

Use of a suitable RNAV system as a means to navigate

on the final approach segment of an instrument approach
procedure based on a VOR, TACAN or NDB signal, is
allowable. The underlying NAVAID must be operational
and the NAVAID monitored for final segment course
alignment. 

6.

For the purpose of paragraph c, “VOR” includes VOR,

VOR/DME, and VORTAC facilities and “compass
locator” includes locator outer marker and locator middle
marker.

d. Alternate Airport Considerations.

 For the

purposes of flight planning, any required alternate
airport must have an available instrument approach
procedure that does not require the use of GPS. This
restriction includes conducting a conventional
approach at the alternate airport using a substitute
means of navigation that is based upon the use of
GPS. For example, these restrictions would apply
when planning to use GPS equipment as a substitute
means of navigation for an out

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of

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service VOR that

supports an ILS missed approach procedure at an
alternate airport. In this case, some other approach
not reliant upon the use of GPS must be available.
This restriction does not apply to RNAV systems
using TSO

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C145/

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C146 WAAS equipment. For

further WAAS guidance, see paragraph 1

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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-
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.

3.

This restriction does not apply to

TSO-C145() and TSO-C146() equipped users
(WAAS users). For further WAAS guidance, see
paragraph 1

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18.

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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

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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

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checks of other airborne systems (for example,

DME/DME/IRU or VOR) useful to mitigate this
otherwise undetected hazard.

REFERENCE

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AIM Paragraph 1

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17, Global Positioning System (GPS)

AIM Paragraph 1

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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.

REFERENCE

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AIM Paragraph 1

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1

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17, Global Positioning System (GPS)

AIM Paragraph 1

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18, Wide Area Augmentation System (WAAS)

c.

If the pilot experiences interruptions while

navigating with GPS, the pilot and ATC may both