AIRPLANE
OPERATIONS
MANUAL
AUTOPILOT
REVISION 36
2-19-10
Page
7
Code
01
AOM-145/1114
ALTITUDE HOLD MODE (ALT)
The Altitude Hold mode generates an altitude error signal from a
reference altitude and provides a pitch command, which allows the
autopilot to maintain altitude.
The Altitude Hold mode is selected by pressing the ALT button on the
Flight Guidance Controller or can also be activated automatically by
the altitude preselect mode. This mode is annunciated on the PFD by
the ALT label.
The mode will be canceled or inhibited if any of the following
conditions occur:
Pressing the ALT button.
Selecting VS, FLC, or SPD modes.
Glide slope capture.
When the air data is invalid.
Pressing the Go Around Button.
Pitch control wheel moved with autopilot engaged.
ALTITUDE PRESELECT MODE (ASEL)
The Altitude Preselect mode provides means for the system to climb
or descend to a predetermined altitude and then level off and maintain
the preselected altitude.
Preselected altitude is set through the ASEL knob on the Flight
Guidance Controller and is displayed on the top right corner of the
PFD. This mode is annunciated by the white ASEL label on the PFD.
Pitch Hold, Speed Hold or Vertical Speed Hold must be used to climb
or descend towards the preselected altitude or Flight Level Change
(FLC).
The ASEL mode will arm automatically if the airplane climbs or
descends towards a preselected altitude. The ASEL mode will
automatically capture and cancel any existing mode at the appropriate
point based on preselected altitude error and vertical speed. The
system will automatically switch to altitude hold mode after the
airplane has leveled off at the selected altitude.
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