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aircraft of the attitude indicator is properly adjusted on the
ground before takeoff, it shows approximately level flight at
normal cruise speed when the pilot completes the level off
from a climb. If further adjustment of the miniature aircraft
is necessary, the other pitch instruments must be used to
maintain level flight while the adjustment is made.
To practice pitch control for level flight using only the
attitude indicator, use the following exercise. Restrict the
displacement of the horizon bar to a one-half bar width, a
bar width up or down, then a one-and-one-half bar width.
One-half, one, and one-and-one-half bar width nose-high
attitudes are shown in Figures 5-4, 5-5, and 5-6.
An instructor pilot can demonstrate these normal pitch
corrections and compare the indications on the attitude
indicator with the airplane’s position to the natural horizon.
Pitch attitude changes for corrections to level flight by reference
to instruments are much smaller than those commonly used
for visual flight. With the airplane correctly trimmed for level
flight, the elevator displacement and the control pressures
necessary to effect these standard pitch changes are usually
very slight. The following are a few helpful hints to help
determine how much elevator control pressure is required.
First, a tight grip on the controls makes it difficult to feel
control pressure changes. Relaxing and learning to control
the aircraft usually takes considerable conscious effort during
the early stages of instrument training.
Second, make smooth and small pitch changes with positive
pressure. With practice, a pilot can make these small pitch
corrections up or down, “freezing” (holding constant) the
one-half, full, and one-and-one-half bar widths on the
attitude indicator.
Third, with the airplane properly trimmed for level flight,
momentarily release all pressure on the elevator control
when becoming aware of tenseness. This is a reminder that
the airplane is stable; except under turbulent conditions, it
will maintain level flight if left alone. Even when no control
change is called for, it will be difficult to resist the impulse
to move the controls. This may be one of the most difficult
initial training problems in instrument flight.
Altimeter
At constant power, any deviation from level flight (except
in turbulent air) is the result of a pitch change. Therefore,
the altimeter gives an indirect indication of the pitch attitude
in level flight, assuming constant power. Since the altitude
5-4
Figure 5-7. Using the Altimeter for Pitch Interpretation, a High
Altitude Means a Nose-High Pitch Attitude.
Figure 5-8. Pitch Correction Following Altitude Increase—Lower
Nose to Correct Altitude Error.
should remain constant when the airplane is in level flight,
any deviation from the desired altitude signals the need for a
pitch change. If the aircraft is gaining altitude, the nose must
be lowered. [Figures 5-7 and 5-8]
The rate of movement of the altimeter needle is as important
as its direction of movement in maintaining level flight
without the use of the attitude indicator. An excessive pitch
deviation from level flight results in a relatively rapid change
of altitude; a slight pitch deviation causes a slow change.
Thus, if the altimeter needle moves rapidly clockwise, assume
a considerable nose-high deviation from level flight attitude.
Conversely, if the needle moves slowly counterclockwise to
indicate a slightly nose-low attitude, assume that the pitch
correction necessary to regain the desired altitude is small.
As the altimeter is added to the attitude indicator in a crosscheck,
a pilot will learn to recognize the rate of movement
of the altimeter needle for a given pitch change as shown on
the attitude indicator.
To practice precision control of pitch in an airplane without
an attitude indicator, make small pitch changes by visual
reference to the natural horizon, and note the rate of
movement of the altimeter. Note what amount of pitch change
gives the slowest steady rate of change on the altimeter. Then
practice small pitch corrections by accurately interpreting
and controlling the rate of needle movement.
An instructor pilot can demonstrate an excessive nose-down
deviation (indicated by rapid movement of the altimeter
needle) and then, as an example, show the result of improper
corrective technique. The normal impulse is to make a
large pitch correction in a hurry, but this inevitably leads
to overcontrolling. The needle slows down, then reverses
direction, and finally indicates an excessive nose-high
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本文链接地址：
Instrument Flying Handbook仪表飞行手册上(78)
