曝光台 注意防骗
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leading the pilot to believe the pitch attitude or direction
attitude of the aircraft has changed when, in fact, it has not.
These false sensations result in the pilot experiencing spatial
disorientation.
Attitude Control
Attitude is defined as “The position of an aircraft as
determined by the relationship of its axes and a reference,
usually the earth’s horizon.” For WSC, the pitch and the roll
are the relevant attitudes.
Most aircraft are generally, by design, inherently stable
platforms and, except in turbulent air, maintain approximately
straight-and-level fl ight if properly trimmed and left alone.
They are designed to maintain a state of equilibrium in
pitch, roll, and yaw. The pilot must be aware, however, that
a change about one axis affects the other axes. The WSC
aircraft is stable in the yaw and pitch axes, but less stable in
the roll axis. The yaw and pitch axes of the WSC are easy
to control, but the roll axis is the challenge for WSC aircraft
control in IMC. The key to emergency aircraft attitude and
directional control, therefore, is to:
• Fly at the normal trim speed. To climb, increase
throttle; to descend, decrease throttle. To fl y level,
fl y at the throttle setting that provides level fl ight.
The vertical speed indicator or altimeter provides
information regarding pitch attitude.
• Resist the tendency to overcontrol the aircraft. Fly
with fi ngertip control. No attitude changes should be
made unless the fl ight instruments indicate a defi nite
need for a change.
• Make all attitude changes smooth and small, yet with
positive pressure.
The primary instrument for roll control is the attitude
indicator if so equipped. [Figures 13-9 and 13-10]
For aircraft not equipped with an attitude indicator, a
magnetic compass [Figure 13-11] or a GPS [Figure 13-12]
are the instruments that can be used for roll control. The
compass stays stationary and the WSC aircraft rotates around
the compass dial. A pilot is fl ying wings level if the compass
heading is not changing. If the compass is changing direction,
the aircraft is banked into a turn. Similarly, the GPS provides
ground track. If fl ying wings level, the GPS ground track is
steady. If the GPS ground track is changing, the aircraft is
in a bank and turning.
Turns
Turns are perhaps the most potentially dangerous maneuver
for the untrained instrument pilot for two reasons:
• The normal tendency of the pilot to overcontrol,
leading to steep banks.
• The inability of the pilot to cope with the instability
resulting from the turn.
As an example, a 180° turn would be the most likely turn to
exit a cloud and return to where there is visibility with the
surface. The direction the turn started should be noted in order
to determine the direction needed to exit the IMC conditions.
For example, if heading North when fl ying into the cloud,
turn 180° and head South to exit the cloud.
13-19
Figure 13-12. Global positioning system (GPS).
Figure 13-13. Level turn.
30
40
50
60
70
80
90
30.0
29.9
29.8
When a turn must be made, the pilot should anticipate and
cope with the relative instability of the roll axis. The smallest
practical bank angle should be used—in any case no more
than 10° bank angle. [Figure 13-13] A shallow bank takes
very little vertical lift from the wings, resulting in little if
any deviation in altitude, and the WSC aircraft can continue
to be fl own at trim speed. It may be helpful to turn 90° and
then reduce the bank and return to level fl ight. This process
may relieve the progressive overbanking that often results
from prolonged turns. Repeat the process twice until heading
in the opposite direction of entry in order to exit. Once on
the proper heading to exit the IMC conditions, maintain this
heading until obtaining visual reference with the surface.
Turns with a magnetic compass or a GPS would be similar
but the only indication of bank angle is the rate at which the
compass or GPS is rotating. The rotation should be slow and
steady and not increase in speed. Any increase in compass
or GPS rotation should be slowed by decreasing the bank
back to level fl ight to avoid increasing the bank. Practicing
gentle turns and observing the rotational speed of the compass
and GPS under VFR conditions will help a pilot recognize
an acceptable rotational speed fl ying at trim speed should
need ever arise.
13-20
Chapter Summary
Most emergency situations can be avoided through proper
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Weight-Shift Control Aircraft Flying Handbook(156)
