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the aircraft at a certain attitude. This allows more time to
devote to the navigation instruments and additional flight
deck duties.
4-9
Figure 4-14. Pitch Control and Power Adjustment Required To Bring Aircraft to Level Flight.
Figure 4-15. Power Instruments.
Figure 4-16. Trim Instruments.
4-10
• Airspeed Indicator—supplies the most pertinent
information concerning performance in level flight
in terms of power output and is primary for power.
Although the attitude indicator is the basic attitude reference,
the concept of primary and supporting instruments does not
devalue any particular flight instrument, when available, in
establishing and maintaining pitch-and-bank attitudes. It is the
only instrument that instantly and directly portrays the actual
flight attitude. It should always be used, when available, in
establishing and maintaining pitch-and-bank attitudes. The
specific use of primary and supporting instruments during
basic instrument maneuvers is presented in more detail in
Chapter 5, Airplane Basic Flight Maneuvers.
Fundamental Skills
During attitude instrument training, two fundamental flight
skills must be developed. They are instrument cross-check
and instrument interpretation, both resulting in positive
aircraft control. Although these skills are learned separately
and in deliberate sequence, a measure of proficiency in
precision flying is the ability to integrate these skills into
unified, smooth, positive control responses to maintain any
prescribed flight path.
Instrument Cross-Check
The first fundamental skill is cross-checking (also called
“scanning” or “instrument coverage”). Cross-checking is the
continuous and logical observation of instruments for attitude
and performance information. In attitude instrument flying,
the pilot maintains an attitude by reference to instruments,
producing the desired result in performance. Observing and
interpreting two or more instruments to determine attitude and
performance of an aircraft is called cross-checking. Although
no specific method of cross-checking is recommended, those
instruments that give the best information for controlling the
aircraft in any given maneuver should be used. The important
instruments are the ones that give the most pertinent
information for any particular phase of the maneuver. These
are usually the instruments that should be held at a constant
indication. The remaining instruments should help maintain
the important instruments at the desired indications, which
is also true in using the emergency panel.
Cross-checking is mandatory in instrument flying. In
visual flight, a level attitude can be maintained by outside
references. However, even then the altimeter must be checked
to determine if altitude is being maintained. Due to human
error, instrument error, and airplane performance differences
in various atmospheric and loading conditions, it is impossible
to establish an attitude and have performance remain constant
for a long period of time. These variables make it necessary
An aircraft is placed in trim by:
• Applying control pressure(s) to establish a desired
attitude. Then, the trim is adjusted so that the aircraft
maintains that attitude when flight controls are
released. The aircraft is trimmed for coordinated flight
by centering the ball of the turn-and-slip indicator.
• Moving the rudder trim in the direction where the
ball is displaced from center. Aileron trim may then
be adjusted to maintain a wings-level attitude.
• Using balanced power or thrust when possible to aid
in maintaining coordinated flight. Changes in attitude,
power, or configuration may require trim adjustments.
Use of trim alone to establish a change in aircraft
attitude usually results in erratic aircraft control.
Smooth and precise attitude changes are best attained
by a combination of control pressures and subsequent
trim adjustments. The trim controls are aids to smooth
aircraft control.
Helicopter Trim
A helicopter is placed in trim by continually cross-checking
the instruments and performing the following:
• Using the cyclic centering button. If the helicopter is so
equipped, this relieves all possible cyclic pressures.
• Using the pedal adjustment to center the ball of the
turn indicator. Pedal trim is required during all power
changes and is used to relieve all control pressures
held after a desired attitude has been attained.
An improperly trimmed helicopter requires constant control
pressures, produces tension, distracts attention from crosschecking,
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Instrument Flying Handbook仪表飞行手册上(68)
