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procedure, assuming required visual references are
available. Approaches without VDPs have not been
assessed for terrain clearance below the MDA, and
may not provide a clear vertical path to the runway at
the normally expected descent angle. Therefore,
pilots must be especially vigilant when descending
below the MDA at locations without VDPs. This does
not necessarily prevent flying the normal angle; it
only means that obstacle clearance in the visual
segment could be less and greater care should be
exercised in looking for obstacles in the visual
segment. Use of visual glide slope indicator (VGSI)
systems can aid the pilot in determining if the aircraft
is in a position to make the descent from the MDA.
However, when the visibility is close to minimums,
the VGSI may not be visible at the start descent point
for a “normal” glidepath, due to its location down the
runway.
3. Accordingly, pilots are advised to carefully
review approach procedures, prior to initiating the
approach, to identify the optimum position(s), and
any unacceptable positions, from which a descent to
landing can be initiated (in accordance with 14 CFR
Section 91.175(c)).
k. Area Navigation (RNAV) Instrument
Approach Charts. Reliance on RNAV systems for
instrument operations is becoming more commonplace
as new systems such as GPS and augmented
GPS such as the Wide Area Augmentation System
(WAAS) are developed and deployed. In order to
support full integration of RNAV procedures into the
National Airspace System (NAS), the FAA
developed a new charting format for IAPs (See
FIG 5−4−9). This format avoids unnecessary
duplication and proliferation of instrument approach
charts. The original stand alone GPS charts, titled
simply “GPS,” are being converted to the newer
format as the procedures are revised. One reason for
the revision could be the addition of WAAS based
minima to the approach chart. The reformatted
approach chart is titled “RNAV (GPS) RWY XX.” Up
to four lines of minima are included on these charts.
GLS (Global Navigation Satellite System [GNSS]
Landing System) was a placeholder for future WAAS
and LAAS minima, and the minima was always listed
as N/A. The GLS minima line has now been replaced
by the WAAS LPV (Localizer Performance with
Vertical Guidance) minima on most RNAV (GPS)
charts. LNAV/VNAV (lateral navigation/vertical
navigation) was added to support both WAAS
7/31/08 AIM
AIM 2/14/08
5−4−20 Arrival Procedures
electronic vertical guidance and Barometric VNAV.
LPV and LNAV/VNAV are both APV procedures as
described in paragraph 5−4−5a7. The original GPS
minima, titled “S−XX,” for straight in runway XX, is
retitled LNAV (lateral navigation). Circling minima
may also be published. A new type of nonprecision
WAAS minima will also be published on this chart
and titled LP (localizer performance). LP will be
published in locations where vertically guided
minima cannot be provided due to terrain and
obstacles and therefore, no LPV or LNAV/VNAV
minima will be published. Current plans call for
LAAS based procedures to be published on a separate
chart and for the GLS minima line to be used only for
LAAS. ATC clearance for the RNAV procedure
authorizes a properly certified pilot to utilize any
minimums for which the aircraft is certified: e.g. a
WAAS equipped aircraft utilize the LPV or LP
minima but a GPS only aircraft may not. The RNAV
chart includes information formatted for quick
reference by the pilot or flight crew at the top of the
chart. This portion of the chart, developed based on
a study by the Department of Transportation, Volpe
National Transportation System Center, is commonly
referred to as the pilot briefing.
1. The minima lines are:
(a) GLS. “GLS” is the acronym for GNSS
landing system; GNSS is the ICAO acronym for
Global Navigation Satellite System (the international
term for all GPS type systems). 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 LAAS
and WAAS procedure publication have evolved, GLS
will now be used only for LAAS 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. LPV identifies
WAAS APV approach minimums with electronic
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