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and contributes to abrupt and erratic attitude
control. The pressures felt on the controls should be only
those applied while controlling the helicopter.
Adjust the pitch attitude, as airspeed changes, to maintain
desired attitude for the maneuver being executed. The bank
must be adjusted to maintain a desired rate of turn, and the
pedals must be used to maintain coordinated flight. Trim must
be adjusted as control pressures indicate a change is needed.
Example of Primary and Support Instruments
Straight-and-level flight at a constant airspeed means that an
exact altitude is to be maintained with zero bank (constant
heading). The primary pitch, bank, and power instruments
used to maintain this flight condition are:
• Altimeter—supplies the most pertinent altitude
information and is primary for pitch.
• Heading Indicator—supplies the most pertinent bank
or heading information and is primary for bank.
4-11
Figure 4-17. Radial Cross-Check.
for the pilot to constantly check the instruments and make
appropriate changes in airplane attitude using cross-checking
of instruments. Examples of cross-checking are explained in
the following paragraphs.
Selected Radial Cross-Check
When the selected radial cross-check is used, a pilot spends
80 to 90 percent of flight time looking at the attitude indicator,
taking only quick glances at the other flight instruments (for
this discussion, the five instruments surrounding the attitude
indicator are called the flight instruments). With this method,
the pilot’s eyes never travel directly between the flight
instruments but move by way of the attitude indicator. The
maneuver being performed determines which instruments to
look at in the pattern. [Figure 4-17]
Inverted-V Cross-Check
In the inverted-V cross-check, the pilot scans from the
attitude indicator down to the turn coordinator, up to the
attitude indicator, down to the VSI, and back up to the attitude
indicator. [Figure 4-18]
Rectangular Cross-Check
In the rectangular cross-check, the pilot scans across
the top three instruments (airspeed indicator, attitude
indicator, and altimeter) and then drops down to scan the
bottom three instruments (VSI, heading indicator, and
turn instrument). This scan follows a rectangular path
(clockwise or counterclockwise rotation is a personal choice).
[Figure 4-19]
This cross-checking method gives equal weight to the
information from each instrument, regardless of its
importance to the maneuver being performed. However, this
method lengthens the time it takes to return to an instrument
critical to the successful completion of the maneuver.
Common Cross-Check Errors
A beginner might cross-check rapidly, looking at the
instruments without knowing exactly what to look for. With
increasing experience in basic instrument maneuvers and
familiarity with the instrument indications associated with
them, a pilot learns what to look for, when to look for it,
and what response to make. As proficiency increases, a pilot
cross-checks primarily from habit, suiting scanning rate and
sequence to the demands of the flight situation. Failure to
maintain basic instrument proficiency through practice can
result in many of the following common scanning errors,
both during training and at any subsequent time.
Fixation, or staring at a single instrument, usually occurs for
a reason, but has poor results. For example, a pilot may stare
at the altimeter reading 200 feet below the assigned altitude,
and wonder how the needle got there. While fixated on the
4-12
Figure 4-18. Inverted-V Cross-Check.
Figure 4-19. Rectangular Cross-Check.
4-13
10,000'
7,500'
5,000'
2,500'
0
10,000'
7,500'
5,000'
2,500'
0
60 80
100
120
140
160
220 200 180
240
250
350
400
KNOTS
300
-
Figure 4-20. Power and Attitude Equal Performance.
instrument, increasing tension may be unconsciously exerted
on the controls, which leads to an unnoticed heading change
that leads to more errors. Another common fixation is likely
when initiating an attitude change. For example, a shallow
bank is established for a 90° turn and, instead of maintaining
a cross-check of other pertinent instruments, the pilot stares at
the heading indicator throughout the turn. Since the aircraft is
turning, there is no need to recheck the heading indicator for
approximately 25 seconds after turn entry. The problem here
may not be entirely due to cross-check error. It may be related
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Instrument Flying Handbook仪表飞行手册上(69)
