曝光台 注意防骗
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34:1 and 20:1 surfaces. These surfaces are inclined
planes that begin 200 feet out from the runway and
5-32
extend outward to 10,000 feet. If there is a penetration
of the 34:1 surface, the published visibility can be no
lower than 3/4 SM. If there is penetration of the 20:1
surface, the published visibility can be no lower than 1
SM with a note prohibiting approaches to the affected
runway at night (both straight-in and circling). [Figure
5-21] Circling may be permitted at night if penetrating
obstacles are marked and lighted. If the penetrating
obstacles are not marked and lighted, a note is published that night circling is “Not Authorized.” Pilots
should be aware of these penetrating obstacles when
entering the visual and/or circling segments of an
approach and take adequate precautions to avoid them.
For RNAV approaches only, the presence of a grey
shaded line from the MDA to the runway symbol in the
profile view, is an indication that the visual segment
below the MDA is clear of obstructions on the 34:1
slope. Absence of the gray shaded area indicates the
34:1 OCS is not free of obstructions.
MISSED APPROACH
Many reasons exist for executing a missed approach.
The primary reason, of course, is that the required
flight visibility prescribed in the IAP being used does
not exist or the required visual references for the runway cannot be seen upon arrival at the DA, DH or
MAP. In addition, according to Part 91, the aircraft
must continuously be in a position from which a
descent to a landing on the intended runway can be
made at a normal rate of descent using normal maneuvers, and for operations conducted under Part 121 or 135,
unless that descent rate will allow touchdown to occur
within the touchdown zone of the runway of intended
landing. [Figure 5-22] CAT II and III approaches call for
different visibility requirements as prescribed by the
Administrator.
Once descent below the DA, DH, or MDA is begun, a
missed approach must be executed if the required visibility is lost or the runway environment is no longer
visible, unless the loss of sight of the runway is a result
of normal banking of the aircraft during a circling
approach. A missed approach procedure is also
required upon the execution of a rejected landing for
any reason, such as men and equipment or animals on
the runway, or if the approach becomes unstabilized
and a normal landing cannot be performed. After the
MAP in the visual segment of a nonprecision approach
there may be hazards when executing a missed
approach below the MDA. Any missed approach after a
DA, DH, or MAP below the DA, DH, or MDA involves
additional risk until established on the published
missed approach procedure course and altitude.
At airports with control towers it is common for ATC to
assign alternate missed approach instructions; even so,
pilots should always be prepared to fly the published
Figure 5-21. Determination of Visibility Minimums.
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missed approach. When a missed approach is executed
prior to reaching the MAP, the pilot is required to continue along the final approach course, at an altitude
above the DA, DH, or MDA, until reaching the MAP
before making any turns. If a turn is initiated prior to
the MAP, obstacle clearance is not guaranteed. It is
appropriate after passing the FAF, and recommended,
where there aren’t any climb restrictions, to begin a
climb to the missed approach altitude without waiting
to arrive at the MAP. Figure 5-23 gives an example of
an altitude restriction that would prevent a climb
between the FAF and MAP. In this situation, the
Orlando Executive ILS or LOC RWY 7 approach altitude is restricted at the BUVAY 3 DME fix to prevent
aircraft from penetrating the overlying protected airspace for approach routes into Orlando International
Airport. If a missed approach is initiated before reaching BUVAY, a pilot may be required to continue
descent to 1,200 feet before proceeding to the MAP and
executing the missed approach climb instructions. In
addition to the missed approach notes on the chart, the
Pilot Briefing Information icons in the profile view
indicate the initial vertical and lateral missed approach
guidance.
The missed approach course begins at the MAP and
continues until the aircraft has reached the designated
fix and a holding pattern has been entered, unless there
is no holding pattern published for the missed
approach. It is common at large airports with high traf-
fic volume to not have a holding pattern depicted at the
designated fix. [Figure 5-24 on page 5-35] In these
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Instrument Procedures Handbook (IPH)仪表程序手册下(120)
