AIRPLANE
OPERATIONS
MANUAL
AUTOPILOT
REVISION 36
2-19-10
Page
11
Code
01
AOM-145/1114
SPEED HOLD MODE (SPD)
The Speed Hold mode is used to maintain airspeed or Mach number
while flying to a new altitude. Indicated airspeed should be used below
25000 ft and Mach number above 25100 ft.
The Speed Hold mode is also designed to provide overspeed and
underspeed protections.
Speed hold mode is selected by pressing the SPD button on the Flight
Guidance Controller. This mode is annunciated on the PFD by the
SPD label, when maintaining IAS, or by the MACH label when
maintaining Mach number. Selection of Speed Hold mode cancels
other vertical modes, except the altitude preselect arm mode and
Glide Slope arm mode.
Speed Hold mode is automatically selected when the FLC button is
pressed and the preselected altitude is above the current altitude.
Different Speed Target can be selected by using the Speed Set knob
in the Flight Guidance Controller. Pressing the SPD knob allows the
pilot to toggle between IAS target and MACH target to set airspeed.
The following protections are provided with this mode:
− Maximum normal acceleration: 0.1 G.
− Maximum normal acceleration on entering overspeed: 0.3 G.
− Maximum airspeed: V
MO
or M
MO
.
− Minimum airspeed: Shaker actuation speed.
− System will maintain the preselected altitude and airspeed.
The mode will be canceled or inhibited if any of the following
conditions occur:
− Pressing the SPD button.
− Selecting ALT, VS, or FLC modes.
− Altitude preselect capture.
− Glide slope capture.
− When air data is invalid.
− Pressing the Go Around Button.
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