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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)).
j. Area Navigation (RNAV) Instrument Approach
Charts. Reliance on RNAV systems for
instrument approach operations is becoming more
commonplace as new systems such as GPS, Wide
Area Augmentation System (WAAS) and Local Area
Augmentation System (LAAS) are developed and
deployed. In order to foster and support full
integration of RNAV into the National Airspace
System (NAS), the FAA has developed a new
charting format for IAPs. (See FIG 5−4−9). This
format avoids unnecessary duplication and proliferation
of instrument approach charts. The approach
minimums for unaugmented GPS (the present GPS
approaches) and WAAS augmented GPS will be
published on the same approach chart. The approach
chart will be titled “RNAV (GPS) RWY XX.” The
first new RNAV approach charts appeared as stand
alone “GPS” procedures, prior to WAAS becoming
operational, with only a LNAV minima line. The
follow−on charts contained as many as four lines of
approach minimums: GLS (Global Navigation
Satellite System [GNSS] Landing System); LNAV/
VNAV (lateral navigation/vertical navigation);
LNAV; and CIRCLING. GLS was a placeholder for
WAAS and LAAS when they became available and
is marked N/A. LNAV/VNAV is a new type of
instrument approach called APV, with lateral and
vertical navigation. The vertical portion can be flown
by approach certified Baro−VNAV and by WAAS
electronic VNAV as well. A new line will be added to
these charts titled LPV. This will replace the GLS N/A
line. The decision of whether the WAAS and LAAS
precision lines of minima will remain on this chart or
be moved to a precision only chart will be determined
later. RNAV procedures which incorporate a final
approach stepdown fix may be published without
vertical navigation, on a separate chart, titled RNAV
(GPS) RWY XX and then Z, Y, X, etc., as indicated
in subparagraph 5−4−5a3. During a transition period
until all GPS procedures are retitled both “RNAV
(GPS)” and “GPS” approach charts and formats will
be published. ATC clearance for the RNAV procedure
authorizes a properly certified pilot to utilize any
landing minimums for which the aircraft is certified.
The RNAV chart includes formatted information
required for quick pilot or flight crew reference
located at the top of the chart. This portion of the
chart, developed based on a study by the Department
of Transportation, Volpe National Transportation
Systems 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 acronym for Global
Navigation Satellite System. The minimums line
labeled GLS will accommodate aircraft equipped
with precision approach certified WAAS receivers
operating to their fullest capability or LAAS and may
support precision (GLS) approach minimums as low
as 200−foot height above touchdown (HAT) and
1/2 statute mile (SM) visibility. This line has been
published as N/A as a place holder for the minima
when published. The WAAS and LAAS precision
minima may be moved to a different chart in the
future.
(b) LPV identifies APV minimums with
electronic lateral and vertical guidance. The lateral
guidance is equivalent to localizer, and the protected
area is considerably smaller than the protected area
AIM 2/19/04
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