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reference.
2. Pilots not equipped to receive the VDP should
fly the approach procedure as though no VDP had
been provided.
g. Visual Portion of the Final Segment. Instrument
procedures designers perform a visual area
obstruction evaluation off the approach end of each
runway authorized for instrument landing, straight−
in, or circling. Restrictions to instrument operations
are imposed if penetrations of the obstruction
clearance surfaces exist. These restrictions vary
based on the severity of the penetrations, and may
include increasing required visibility, denying VDPs
and prohibiting night instrument operations to the
runway.
h. Vertical Descent Angle (VDA) on Nonprecision
Approaches. The FAA intends to eventually
publish VDAs on all nonprecision approaches.
Published along with the VDA is the threshold
crossing height (TCH); i.e., the height of the descent
angle above the landing threshold. The descent angle
describes a computed path from the final approach
fix (FAF) and altitude to the runway threshold at the
published TCH. The optimum descent angle is
3.00 degrees; and whenever possible the approach
will be designed to accommodate this angle.
1. The VDA provides the pilot with information
not previously available on nonprecision approaches.
It provides the means for the pilot to establish a
stabilized approach descent from the FAF or
stepdown fix to the TCH. Stabilized descent along
this path is a key factor in the reduction of controlled
flight into terrain (CFIT) incidents. Pilots can use the
published angle and estimated/actual groundspeed to
find a target rate of descent from a rate of descent
table published in the back of the U.S. Terminal
Procedures Publication.
2. Normally, the VDA will first appear on the
nonprecision approach chart as the procedure is
amended through the normal process. However, in
some cases, pilots may see this data provided via a
D−NOTAM.
EXAMPLE−
GPS RWY 9L, AMDT 2. . .
ADD: AWZAC WP TO RW09L: 2.96 DEGREES,
TCH 50.
THIS IS GPS RWY 9L, AMDT 2A
Translated, this means that the currently published
GPS RWY 9L procedure, Amendment 2, is changed
by the addition of a 2.96−degree descent angle from
AWZAC WP to a point 50 feet above the RWY 9L
threshold. This constitutes Amendment 2A to the
published procedure.
3. Pilots should be aware that the published
angle is for information only − it is strictly advisory
in nature. There is no implicit additional obstacle
protection below the MDA. Pilots must still respect
the published minimum descent altitude (MDA)
unless the visual cues stated in 14 CFR Section
91.175 are present. In rare cases, the published
procedure descent angle will not coincide with the
Visual Glide Slope Indicator (VGSI); VASI or PAPI.
In these cases, the procedure will be annotated:
“VGSI and descent angle not coincident.”
i. Pilot Operational Considerations When
Flying Nonprecision Approaches. The missed
approach point (MAP) on a nonprecision approach is
not designed with any consideration to where the
aircraft must begin descent to execute a safe landing.
It is developed based on terrain, obstructions,
NAVAID location and possibly air traffic considerations.
Because the MAP may be located anywhere
from well prior to the runway threshold to past the
opposite end of the runway, the descent from the
Minimum Descent Altitude (MDA) to the runway
threshold cannot be determined based on the MAP
location. Descent from MDA at the MAP when the
MAP is located close to the threshold would require
an excessively steep descent gradient to land in the
normal touchdown zone. Any turn from the final
approach course to the runway heading may also be
a factor in when to begin the descent.
1. Pilots are cautioned that descent to a
straight−in landing from the MDA at the MAP may
be inadvisable or impossible, on a nonprecision
approach, even if current weather conditions meet the
published ceiling and visibility. Aircraft speed, height
above the runway, descent rate, amount of turn and
runway length are some of the factors which must be
2/19/04 AIM
Arrival Procedures 5−4−19
considered by the pilot to determine if a landing can
be accomplished.
2. Visual descent points (VDPs) provide pilots
with a reference for the optimal location to begin
descent from the MDA, based on the designed
vertical descent angle (VDA) for the approach
procedure, assuming required visual references are
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