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the planned approach. Any crossing restrictions for
the STAR might need to be programmed as well.
The most common crossing restrictions, whether
mandatory or “to be expected,” are usually automatically programmed when the STAR is selected,
but can be changed by ATC at any time. Other items
that need to be set up are dictated by aircraft-specific procedures, such as autopilot, auto-throttles,
auto-brakes, pressurization system, fuel system,
seat belt signs, anti-icing/de-icing equipment,
igniters, etc.
AUTOPILOT MODES
In general, an autopilot can be used to fly approaches
even if the FMC is inoperative (refer to the specific
airplane’s minimum equipment list [MEL] to determine authorization for operating with the FMC
inoperative). Whether or not the FMC is available,
use of the autopilot should be discussed during the
approach briefing, especially regarding the use of the
altitude pre-selector and auto-throttles, if equipped.
The AFM for the specific airplane outlines procedures and limitations required for the use of the
autopilot during an instrument approach in that
aircraft.
There are just as many different autopilot modes to
climb or descend the airplane, as there are terms for
these modes (ex. Level Change [LVL CHG], Vertical
Speed [V/S], VNAV, Takeoff/Go Around [TO/GA],
etc.). The pilot controls the airplane through the
autopilot by selecting pitch modes and/or roll
modes, as well as the associated auto-throttle modes.
This panel, sometimes called a mode control panel,
is normally accessible to both pilots. Most aircraft
with sophisticated auto-flight systems and autothrottles have the capability to select modes that
climb the airplane with maximum climb thrust and
descend the airplane with the throttles at idle (LVL
CHG, Flight Level Change [FL CHG], Manage
Level, etc.). They also have the capability to
“capture,” or level off at pre-selected altitudes, as
well as track a LOC and glide slope (G/S) or a VOR
course. If the airplane is RNAV equipped, the autopilot
will also track the RNAV generated course. Most of
these modes will be used at some point during an
instrument approach using the autopilot.
Additionally, these modes can be used to provide
flight director (FD) guidance to the pilot while
hand-flying the aircraft.
For the purposes of this precision approach example,
the auto-throttles are engaged when the autopilot is
engaged and specific airspeed and configuration
changes will not be discussed. The PF controls
airspeed with the speed selector on the mode control panel and calls for flaps and landing gear as
5-29
needed, which the PM will select. The example in
figure 5-20 begins with the airplane 5 NM northwest
of BROWN at 4,500 feet with the autopilot engaged,
and the flight has been cleared to track the Rwy 12
LOC inbound. The current roll mode is LOC with
the PF’s NAV radio tuned to the LOC frequency of
109.3; and the current pitch mode is altitude hold
(ALT HOLD). Approach control clears the airplane
for the approach. The PF makes no immediate
change to the autopilot mode to prevent the aircraft
from capturing a false glide slope; but the PM resets
the altitude selector to 2,200 feet. The aircraft will
remain level because the pitch mode remains in ALT
HOLD until another pitch mode is selected. Upon
reaching BROWN, the PF selects LVL CHG as the
pitch mode. The auto-throttles retard to idle as the
Figure 5-20. Example Approaches Using Autopilot.
5-30
airplane begins a descent. Approaching 2,200 feet,
the pitch mode automatically changes to altitude
acquire (ALT ACQ) then to ALT HOLD as the
airplane levels at 2,200 feet. In addition to slowing the airplane and calling for configuration
changes, the PF selects approach mode (APP). The
roll mode continues to track the LOC and the pitch
mode remains in ALT HOLD; however, the G/S
mode arms. Selecting APP once the aircraft has
leveled at the FAF altitude is a suggested technique
to ensure that the airplane captures the glide slope
from below, and that a false glide slope is not being
tracked.
The PF should have the aircraft fully configured for
landing before intercepting the glide slope to ensure a
stabilized approach. As the airplane intercepts the glide
slope, the pitch mode changes to G/S. Once the glide
slope is “captured” by the autopilot, the PM can select
the missed approach altitude in the altitude pre-selector, as requested by the PF. The airplane will continue
to track the glide slope. The minimum altitude at which
　
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本文鏈接地址：Instrument Procedures Handbook (IPH)儀表程序手冊下(117)