6/17/21
AIM
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
−
of
−
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
−
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-
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
−
1
−
18.
1
−
2
−
4. Recognizing, Mitigating and
Adapting to GPS Interference (Jamming or
Spoofing)
a.
The low
−
strength data transmission signals
from GPS satellites are vulnerable to various
anomalies that can significantly reduce the reliability
of the navigation signal. Because of the many uses of
GPS in aviation (e.g., navigation, ADS
−
B, terrain
awareness/warning systems), operators of aircraft
using GPS need to be aware of these vulnerabilities,
and be able to recognize and adjust to degraded
signals. Aircraft should have additional navigation
equipment for their intended route.
b.
GPS signals are vulnerable to intentional and
unintentional interference from a wide variety of
sources, including radars, microwave links, iono-
sphere effects, solar activity, multi
−
path error,
satellite communications, GPS repeaters, and even
some systems onboard the aircraft. In general, these
types of unintentional interference are localized and
intermittent. Of greater and growing concern is the
intentional and unauthorized interference of GPS
signals by persons using “jammers” or “spoofers” to
disrupt air navigation by interfering with the
reception of valid satellite signals.
Performance
−
Based Navigation (PBN) and Area Navigation (RNAV)
1
−
2
−
9