AIM
4/3/14
5−4−22
Arrival Procedures
Navigation; VNAV stands for Vertical Navigation.
This minima line can be flown by aircraft with a
statement in the Aircraft Flight Manual that the
installed equipment supports GPS approaches and
has an approach−approved barometric VNAV, or if
the aircraft has been demonstrated to support
LNAV/VNAV approaches. This includes Class 2, 3
and 4 TSO−C146 GPS/WAAS equipment. Aircraft
using LNAV/VNAV minimums will descend to
landing via an internally generated descent path
based on satellite or other approach approved VNAV
systems. Since electronic vertical guidance is
provided, the minima will be published as a DA.
Other navigation systems may be specifically
authorized to use this line of minima. (See Section A,
Terms/Landing Minima Data, of the U.S. Terminal
Procedures books.)
(d) LP.
“LP” is the acronym for localizer
performance. Approaches to LP lines of minima take
advantage of the improved accuracy of WAAS to
provide approaches, with lateral guidance and
angular guidance. Angular guidance does not refer to
a glideslope angle but rather to the increased lateral
sensitivity as the aircraft gets closer to the runway,
similar to localizer approaches. However, the LP line
of minima is a Minimum Descent Altitude (MDA)
rather than a DA (H). Procedures with LP lines of
minima will not be published with another approach
that contains approved vertical guidance
(LNAV/VNAV or LPV). It is possible to have LP and
LNAV published on the same approach chart but LP
will only be published if it provides lower minima
than an LNAV line of minima. LP is not a fail−down
mode for LPV. LP will only be published if terrain,
obstructions, or some other reason prevent publishing
a vertically guided procedure. WAAS avionics may
provide GNSS−based advisory vertical guidance
during an approach to an LP line of minima.
Barometric altimeter information remains the
primary altitude reference for complying with any
altitude restrictions. WAAS equipment may not
support LP, even if it supports LPV, if it was approved
before TSO−C145b and TSO−C146b. Receivers
approved under previous TSOs may require an
upgrade by the manufacturer in order to be used to fly
to LP minima. Receivers approved for LP must have
a statement in the approved Flight Manual or
Supplemental Flight Manual including LP as one of
the approved approach types.
(e) LNAV.
This minima is for lateral
navigation only, and the approach minimum altitude
will be published as a minimum descent altitude
(MDA). LNAV provides the same level of service as
the present GPS stand alone approaches. LNAV
minimums support the following navigation systems:
WAAS, when the navigation solution will not support
vertical navigation; and, GPS navigation systems
which are presently authorized to conduct GPS
approaches.
NOTE
−
GPS receivers approved for approach operations in
accordance with: AC 20
−138, Airworthiness Approval of
Positioning and Navigation Systems, qualify for this min-
ima. WAAS navigation equipment must be approved in
accordance with the requirements specified in
TSO
−C145() or TSO−C146() and installed in accordance
with Advisory Circular AC 20
−138.
2.
Other systems may be authorized to utilize
these approaches. See the description in Section A of
the U.S. Terminal Procedures books for details.
Operational approval must also be obtained for
Baro−VNAV systems to operate to the LNAV/VNAV
minimums. Baro−VNAV may not be authorized on
some approaches due to other factors, such as no local
altimeter source being available. Baro−VNAV is not
authorized on LPV procedures. Pilots are directed to
their local Flight Standards District Office (FSDO)
for additional information.
NOTE
−
RNAV and Baro
−VNAV systems must have a manufacturer
supplied electronic database which must include the
waypoints, altitudes, and vertical data for the procedure to
be flown. The system must be able to retrieve the procedure
by name from the aircraft navigation database, not just as
a manually entered series of waypoints.
3. ILS or RNAV (GPS) charts.
(a)
Some RNAV (GPS) charts will also con-
tain an ILS line of minima to make use of the ILS
precision final in conjunction with the RNAV GPS
capabilities for the portions of the procedure prior to
the final approach segment and for the missed ap-
proach. Obstacle clearance for the portions of the
procedure other than the final approach segment is
still based on GPS criteria.
NOTE
−
Some GPS receiver installations inhibit GPS navigation
whenever ANY ILS frequency is tuned. Pilots flying
aircraft with receivers installed in this manner must wait
until they are on the intermediate segment of the procedure