AIM

8/15/19

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22

Arrival Procedures

1.

The minima lines are:

(a) GLS.

“GLS” is the acronym for GBAS

Landing System. The U.S. version of GBAS has
traditionally been referred to as LAAS. The
worldwide community has adopted GBAS as the
official term for this type of navigation system. To
coincide with international terminology, the FAA is
also adopting the term GBAS to be consistent with the
international community. This line was originally
published as a placeholder for both WAAS and LAAS
minima and marked as N/A since no minima was
published. As the concepts for GBAS and WAAS
procedure publication have evolved, GLS will now
be used only for GBAS minima, which will be on a
separate approach chart. Most RNAV(GPS) approach
charts have had the GLS minima line replaced by a
WAAS LPV line of minima.

(b) LPV. 

“LPV” is the acronym for localizer

performance with vertical guidance. RNAV (GPS)
approaches to LPV lines of minima take advantage of
the improved accuracy of WAAS lateral and vertical
guidance to provide an approach that is very similar
to a Category I Instrument Landing System (ILS).
The approach to LPV line of minima is designed for
angular guidance with increasing sensitivity as the
aircraft gets closer to the runway. The sensitivities are
nearly identical to those of the ILS at similar
distances. This was done intentionally to allow the
skills required to proficiently fly an ILS to readily
transfer to flying RNAV (GPS) approaches to the
LPV line of minima. Just as with an ILS, the LPV has
vertical guidance and is flown to a DA. Aircraft can
fly this minima line with a statement in the Aircraft
Flight Manual that the installed equipment supports
LPV approaches. This includes Class 3 and 4
TSO

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C146 GPS/WAAS equipment.

(c) LNAV/VNAV.

 LNAV/VNAV identifies

APV minimums developed to accommodate an
RNAV IAP with vertical guidance, usually provided
by approach certified Baro

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VNAV, but with lateral

and vertical integrity limits larger than a precision
approach or LPV. LNAV stands for Lateral
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

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approved barometric VNAV, or if

the aircraft has been demonstrated to support
LNAV/VNAV approaches. This includes Class 2, 3

and 4 TSO

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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

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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

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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

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C145b and TSO

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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