曝光台 注意防骗
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the PF is authorized to disconnect the autopilot is
airplane specific (Example, 50 feet below DA, DH,
or MDA but not less than 50 feet AGL). The PF can
disconnect the autopilot at any time prior to reaching
this altitude during a CAT I approach. The initial
missed approach is normally hand flown with flight
director guidance unless both autopilots are engaged
for autoland during a CAT II or III approach.
The differences when flying the underlying nonprecision approach begin when the aircraft has leveled off
at 2,200 feet. Once ALT HOLD is annunciated the
MDA is selected by the PM as requested by the PF. It
is extremely important for both pilots to be
absolutely sure that the correct altitude is selected
for the MDA so that the airplane will not inadvertently descend below the MDA. For aircraft that the
altitude pre-selector can only select 100-foot increments, the MDA for this approach must be set at 800
feet instead of 740 feet.
Vertical speed mode is used from the FAF inbound
to allow for more precise control of the descent. If
the pilots had not selected the MDA in the altitude
pre-selector window, the PF would not be able to
input a V/S and the airplane would remain level. The
autopilot mode will change from ALT ACQ to ALT
HOLD as the airplane levels at 800 feet. Once ALT
HOLD is annunciated, the PF calls for the missed
approach altitude of 4,000 feet to be selected in the
altitude pre-selector window. This step is very
important because accurate FD guidance will not be
available to the PF during a missed approach if the
MDA is left in the window.
NOTE: See Maximum Acceptable Descent Rates
under the heading Descent Rates and Glidepaths for
Nonprecision Approaches.
STABILIZED APPROACH
In instrument meteorological conditions (IMC), you
must continuously evaluate instrument information
throughout an approach to properly maneuver the
aircraft (or monitor autopilot performance) and to
decide on the proper course of action at the decision
point (DA, DH, or MAP). Significant speed and configuration changes during an approach can seriously
degrade situational awareness and complicate the
decision of the proper action to take at the decision
point. The swept wing handling characteristics at
low airspeeds and slow engine-response of many turbojets further complicate pilot tasks during approach
and landing operations. You must begin to form a
decision concerning the probable success of an
approach before reaching the decision point. Your
decision-making process requires you to be able to
determine displacements from the course or glidepath centerline, to mentally project the aircraft’s
three-dimensional flight path by referring to flight
instruments, and then apply control inputs as necessary to achieve and maintain the desired approach
path. This process is simplified by maintaining a
constant approach speed, descent rate, vertical flight
path, and configuration during the final stages of an
approach. This is referred to as the stabilized
approach concept.
A stabilized approach is essential for safe turbojet
operations and commercial turbojet operators must
establish and use procedures that result in stabilized
approaches. A stabilized approach is also strongly
recommended for propeller-driven airplanes and helicopters. You should limit configuration changes at
low altitudes to those changes that can be easily
accommodated without adversely affecting your
workload. For turbojets, the airplane must be in an
approved configuration for landing or circling, if
appropriate, with the engines spooled up, and on the
correct speed and flight path with a descent rate of
less than 1,000 FPM before descending below the
following minimum stabilized approach heights:
• For all straight-in instrument approaches (this
includes contact approaches) in IFR weather conditions, the approach must be stabilized before
descending below 1,000 feet above the airport or
TDZE.
• For visual approaches and straight-in instrument
approaches in VFR weather conditions, the
approach must be stabilized before descending
below 500 feet above the airport elevation.
5-31
• For the final segment of a circling approach
maneuver, the approach must be stabilized 500
feet above the airport elevation or at the MDA,
whichever is lower.
These conditions must be maintained throughout the
approach until touchdown for the approach to be
considered a stabilized approach. This also helps you
to recognize a windshear situation should abnormal
indications exist during the approach.
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本文链接地址：
Instrument Procedures Handbook (IPH)仪表程序手册下(118)
