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the instrument takeoff, all flight maneuvers can be performed
on “partial panel” with the Attitude Heading Reference
System (AHRS) unit simulated or rendered inoperative.
Airplane Basic
Flight Maneuvers
Chapter 5, Section II
Using an Electronic Flight Display
5-34
Figure 5-47. Pitch Attitude and Airspeed in Level Flight, Slow
Cruise Speed.
Figure 5-48. Pitch Attitude Decreasing and Airspeed Increasing—Indicates Need to Increase Pitch.
Straight-and-Level Flight
Pitch Control
The pitch attitude of an airplane is the angle between the
longitudinal axis of the airplane and the actual horizon.
In level flight, the pitch attitude varies with airspeed and
load. For training purposes, the latter factor can normally
be disregarded in small airplanes. At a constant airspeed,
there is only one specific pitch attitude for level flight. At
slow cruise speeds, the level flight attitude is nose-high with
indications as in Figure 5-47; at fast cruise speeds, the level
flight attitude is nose-low. [Figure 5-48] Figure 5-49 shows
the indications for the attitude at normal cruise speeds.
The instruments that directly or indirectly indicate pitch on
the Primary Flight Display (PFD) are the attitude indicator,
altimeter, vertical speed indicator (VSI), airspeed indicator
(ASI), and both airspeed and altitude trend indicators.
Attitude Indicator
The attitude indicator gives the pilot a direct indication of
the pitch attitude. The increased size of the attitude display
on the EFD system greatly increases situational awareness
for the pilot. Most attitude indicators span the entire width
of the PFD screen.
The aircraft pitch attitude is controlled by changing the
deflection of the elevator. As the pilot pulls back on the
control yoke causing the elevator to rise, the yellow chevron
will begin to show a displacement up from the artificial
horizon line. This is caused by the AHRS unit sensing the
changing angle between the longitudinal plane of the earth
and the longitudinal axis of the aircraft.
The attitude indicator displayed on the PFD screen is a
representation of outside visual cues. Rather than rely on
the natural horizon visible during visual flight rules (VFR)
flight, the pilot must rely on the artificial horizon of the
PFD screen.
During normal cruise airspeed, the point of the yellow
chevron (aircraft symbol) will be positioned on the artificial
horizon. Unlike conventional attitude indicators, the EFD
attitude indicator does not allow for manipulating the position
of the chevron in relationship to the artificial horizon. The
position is fixed and therefore will always display the pitch
angle as calculated by the AHRS unit.
5-35
Figure 5-49. Various Pitch Attitudes (Right), Aircraft Shown in
Level Flight.
Figure 5-50. Pitch Indications for Various Attitudes (1° through 5°). Figure 5-51. Pitch Illustrated at 10°.
The attitude indicator only shows pitch attitude and does
not indicate altitude. A pilot should not attempt to maintain
level flight using the attitude indicator alone. It is important
for the pilot to understand how small displacements both up
and down can affect the altitude of the aircraft. To achieve
this, the pilot should practice increasing the pitch attitude
incrementally to become familiar with how each degree of
pitch changes the altitude. [Figures 5-50 and 5-51] In both
cases, the aircraft will slow and gain altitude.
The full height of the chevron is approximately 5° and
provides an accurate reference for pitch adjustment. It is
imperative that the pilot make the desired changes to pitch
by referencing the attitude indicator and then trimming off
any excess control pressures. Relieving these pressures will
allow for a more stabilized flight and will reduce pilot work
load. Once the aircraft is trimmed for level flight, the pilot
must smoothly and precisely manipulate the elevator control
forces in order to change the pitch attitude.
To master the ability to smoothly control the elevator, a pilot
must develop a very light touch on the control yoke. The
thumb and two fingers are normally sufficient to move the
control yoke. The pilot should avoid griping the yoke with
a full fist. When a pilot grips the yoke with a full fist, there
is a tendency to apply excess pressures, thus changing the
aircraft attitude.
Practice making smooth, small pitch changes both up and
down until precise corrections can be made. With practice
a pilot will be able to make pitch changes in 1° increments,
smoothly controlling the attitude of the aircraft.
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Instrument Flying Handbook仪表飞行手册上(98)
