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5-53
indicator displays approximately 112°. The necessary
calculations are:
15° bank (standard rate) ÷ 2 = 7.5°
120° – 7.5° = 112.5°
By utilizing this technique the pilot is better able to judge if
any modifications need to be made to the amount of lead once
the amount of over- or undershooting is established.
Timed Turns
Timed turns to headings are performed in the same fashion
with an EFD as with an analog equipped aircraft. The
instrumentation used to perform this maneuver is the turn rate
indicator as well as the clock. The purpose of this maneuver
is to allow the pilot to gain proficiency in scanning as well
as to further develop the pilot’s ability to control the aircraft
without standard instrumentation.
Timed turns become essential when controlling the aircraft
with a loss of the heading indicator. This may become
necessary due to a loss of the AHRS unit or the magnetometer.
In any case, the magnetic compass will still be available for
navigation. The reason for timed turns instead of magnetic
compass turns is the simplicity of the maneuver. Magnetic
compass turns require the pilot to take into account various
errors associated with the compass; timed turns do not.
Prior to initiating a turn, determine if the standard rate
indication on the turn rate indicator will actually deliver a
3° per second turn. To accomplish this, a calibration must
be made. Establish a turn in either direction at the indicated
standard rate. Start the digital timer as the compass rolls past
a cardinal heading. Stop the timer once the compass card
rolls through another cardinal heading. Roll wings level and
compute the rate of turn. If the turn rate indicator is calibrated
and indicating correctly, 90° of heading change should take
30 seconds. If the time taken to change heading by 90° is
more or less than 30 seconds, then a deflection above or
below the standard rate line needs to be made to compensate
for the difference. Once the calibration has been completed
in one direction, proceed to the opposite direction. When
both directions have been calibrated, apply the calibrated
calculations to all timed turns.
In order to accomplish a timed turn, the amount of heading
change needs to be established. For a change in heading from
120° to a heading of 360°, the pilot calculates the difference
and divides that number by 3. In this case, 120° divided by
3° per second equals 40 seconds. This means that it would
take 40 seconds for an aircraft to change heading 120° if that
aircraft were held in a perfect standard rate turn. Timing for
the maneuver should start as the aircraft begins rolling into
the standard rate turn. Monitor all flight instruments during
this maneuver. The primary pitch instrument is the altimeter.
The primary power instrument is the ASI and the primary
bank instrument is the turn rate indicator.
Once the calculated time expires, start a smooth coordinated
roll-out. As long as the pilot utilizes the same rate of roll-in as
roll-out, the time it takes for both will not need to be included
in the calculations. With practice the pilot should level the
wings on the desired heading. If any deviation has occurred,
make small corrections to establish the correct heading.
Compass Turns
The magnetic compass is the only instrument that requires
no other source of power for operation. In the event of an
AHRS or magnetometer failure, the magnetic compass is
the instrument the pilot uses to determine aircraft heading.
For a more detailed explanation on the use of the magnetic
compass, see page 5-21.
Steep Turns
For the purpose of instrument flight training, a steep turn is
defined as any turn in excess of standard rate. A standard rate
turn is defined as 3° per second. The bank angle that equates
to a turn rate of 3° per second varies according to airspeed.
As airspeed increases, the bank angle must be increased.
The exact bank angle that equates to a standard rate turn is
unimportant. Normal standard rate turn bank angles range
from 10° to 20°. The goal of training in steep turn maneuvers
is pilot proficiency in controlling the aircraft with excessive
bank angles.
Training in excessive bank angles will challenge the pilot in
honing cross-checking skills and improve altitude control
throughout a wider range of flight attitudes. Although the
current instrument flight check practical test standards (PTS)
do not call for a demonstration of steep turns on the certification
check flight, this does not eliminate the need for the instrument
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Instrument Flying Handbook仪表飞行手册上(111)
