Trio Avionics EZ Pilot - v 1.9 - Manual (Page 17)

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CRS 175 TRN 180
TRK>000 <---♦--->
BTW♦175 TOP>0.3
TRK>176 XTKX0.31
The TOP function is deactivated by setting the TOP field to 0.0 using the L-R switch, or
by simply cycling power to the EZ Pilot using the POWER switch.
When activated, note that the arrow on
the XTK changes from an outline arrow
(
> ) to a fully filled arrow (
X
). Also note
that there is a flashing “
♦
” diamond
indicator present after the BTW label in the TRK mode. The TOP setting will also be
flashed in the upper right display field periodically. These indicators alert you that the
TOP feature is active.
.
3.2.13 Automatic Course Reversal
In an effort to increase safety and save lives, this mode may be implemented as an
emergency aid to the VFR pilot who inadvertently enters IMC conditions and needs to
execute an immediate course reversal.
It is important to realize that the autopilot must be turned on and receiving a good GPS
data signal for proper operation. You may be tracking a flight plan but a sudden IMC
encounter may not leave you with an opportunity to reprogram your GPS to invert the
flight plan. This procedure does not require you to adjust your GPS receiver.
If you are manually flying your aircraft, this procedure will also work because the servo
does not have to be engaged to initiate this emergency procedure.
The procedure is simple and straightforward. Press and hold the MODE button for three
seconds. That’s all you need to do!
After three seconds the following will occur:
• The servo will be energized (if off) and the wing leveler function will engage.
• The upper right display line will read “TRN 180”
• The lower right display line will be forced to the turn coordinator display
• A 175 degree right course reversal will be executed.
The display screen will change as shown.
(The turn coordinator will occupy the
entire lower line if it was set to LARGE).
The reversed groundtrack will remain in
effect until cancelled by selecting another mode (or using the PCS mode) .
If a left course reversal is desired, then hold the L-R switch to the left while pressing the
MODE switch. A left 175 degree left course reversal will then be executed.
Note: You are undoubtedly wondering why the turn is limited to 175 degrees instead of 180
degrees. It is to assure a predictable outcome in an emergency situation. In normal
operation, when a course reversal is commanded by the GPS (invert flight plan) the
autopilot will turn the shortest arc distance. For instance, if the plane is pointed even a
fraction of a degree to the left of course, the turn will be to the left, and vise-versa.
Additionally, small gyro disturbances and GPS update irregularities could cause ambiguity
in turn direction. Therefore, a five degree “buffer” is introduced to absolutely assure that the
aircraft will always turn right (or left, if so commanded by the pilot). This guarantees a
predictable result in a possible emergency situation