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around the obstruction. (See FIG 5−4−13.)
1. The minimum vectoring altitude in each
sector provides 1,000 feet above the highest obstacle
in nonmountainous areas and 2,000 feet above the
highest obstacle in designated mountainous areas.
Where lower MVAs are required in designated
mountainous areas to achieve compatibility with
terminal routes or to permit vectoring to an IAP,
1,000 feet of obstacle clearance may be authorized
with the use of Airport Surveillance Radar (ASR).
The minimum vectoring altitude will provide at least
300 feet above the floor of controlled airspace.
NOTE−
OROCA is an off−route altitude which provides obstruction
clearance with a 1,000 foot buffer in nonmountainous
terrain areas and a 2,000 foot buffer in designated
mountainous areas within the U.S. This altitude may not
provide signal coverage from ground−based navigational
aids, air traffic control radar, or communications
coverage.
2. Because of differences in the areas considered
for MVA, and those applied to other minimum
altitudes, and the ability to isolate specific obstacles,
some MVAs may be lower than the nonradar
Minimum En Route Altitudes (MEAs), Minimum
Obstruction Clearance Altitudes (MOCAs) or other
minimum altitudes depicted on charts for a given
location. While being radar vectored, IFR altitude
assignments by ATC will be at or above MVA.
f. Visual Descent Points (VDPs) are being
incorporated in nonprecision approach procedures.
The VDP is a defined point on the final approach
course of a nonprecision straight-in approach
procedure from which normal descent from the MDA
to the runway touchdown point may be commenced,
provided visual reference required by 14 CFR
Section 91.175(c)(3) is established. The VDP will
normally be identified by DME on VOR and LOC
AIM 2/14/08
5−4−18 Arrival Procedures
procedures and by along−track distance to the next
waypoint for RNAV procedures. The VDP is
identified on the profile view of the approach chart by
the symbol: V.
1. VDPs are intended to provide additional
guidance where they are implemented. No special
technique is required to fly a procedure with a VDP.
The pilot should not descend below the MDA prior to
reaching the VDP and acquiring the necessary visual
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. Charting of Close in Obstacles on Instrument
Procedure Charts. Obstacles that are close to
the airport may be depicted in either the planview of
the instrument approach chart or the airport sketch.
Obstacles are charted in only one of the areas, based
on space available and distance from the runway.
These obstacles could be in the visual segment of the
instrument approach procedure. On nonprecision
approaches, these obstacles should be considered
when determining where to begin descent from the
MDA (see “Pilot Operational Considerations When
Flying Nonprecision Approaches” in this paragraph).
i. Vertical Descent Angle (VDA) on Nonprecision
Approaches. FAA policy is to publish VDAs on
all nonprecision approaches. Published along with
VDA is the threshold crossing height (TCH) that was
used to compute the angle. The descent angle may be
computed from either the final approach fix (FAF), or
a stepdown fix, to the runway threshold at the
published TCH. A stepdown fix is only used as the
start point when an angle computed from the FAF
would place the aircraft below the stepdown fix
altitude. The descent angle and TCH information are
charted on the profile view of the instrument
approach chart following the fix the angle was based
on. The optimum descent angle is 3.00 degrees; and
whenever possible the approach will be designed
using this angle.
1. The VDA provides the pilot with information
not previously available on nonprecision approaches.
It provides a means for the pilot to establish a
stabilized descent from the FAF or stepdown fix to the
　
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