The altitude alert function works in conjunction with altitude preselect (ASEL) mode, which is
described below. The only difference in operation of altitude alert function alone is that the flight
director and/or autopilot need not be engaged for altitude alert to function. The altitude alert
annunciations are controlled by the pertinent flight director, which is selected by the autopilot couple
switch (AP XFER FD1/AP XFER FD2), and are therefore based on the barometrically corrected
altitude displayed on the same side of the cockpit. If the altitude set knob is moved or the glide slope
capture mode is active, the annunciations of altitude alert will be cancelled.
PRIMUS 1000 SYSTEM OPERATION
The Primus 1000 system incorporates a wide variety of capabilities that produces one of the most
precise, flexible and easy to use systems in airplanes today. The flight director (FD) and autopilot
(AP) can be used independently or together. The airplane may be flown manually, using the
guidance provided by the modes selected on the flight director, or when the autopilot is engaged and
coupled to the flight director it will control the airplane using the commands generated by the flight
director computer. Disengagement of the autopilot will have no effect on the FD modes in operation
at the moment of disengagement, except when using the go-around button, in which case a wings
level 10° nose up attitude will be commanded and all other FD modes will be reset. When the
autopilot is engaged without any mode selected, manual pitch and roll commands may be made by
means of the turn knob and pitch wheel on the autopilot controller. Touch control steering (TCS) can
be used to maneuver the airplane or to modify the commands to the FD and AP. If the autopilot is not
engaged, the TCS button can be used to synchronize the command bars to the airplane attitude. If
HDG mode has been selected, BANK LIMIT mode may be engaged and the maximum bank angle
will be limited to approximately 14°.
The Primus 1000 system in the Citation XLS operates through displays of the pilot's (or copilot's)
electronic flight instrument system (EFIS). The systems of autopilot and EFIS are integrated, and
unnecessary system redundancy has thereby been eliminated. The result is an overall simplification
over previous systems, and greatly simplified interface requirements for the flight director function. If
a particular EFIS unit is operational, the flight director will also be operational, and conversely if the
EFIS has failed, the flight director will also be failed. The display is available as a single-cue or a
double-cue (cross-pointer) presentation, the selection of which is made by means of a menu. The
presentation upon power-up is configurable. Glideslope information is presented on the right side of
the electronic attitude direction indicator (ADI) section of the primary flight display (PFD).
The autopilot may be switched to the pilot's flight director (FD 1) or the copilot's flight director (FD 2)
by means of an illuminated selector switch (FD/AP PFD1 / FD/AP PFD2) located on the center
instrument panel. This switch determines only which flight director system provides guidance to the
autopilot.
BASIC AUTOPILOT
The basic autopilot, without any inputs from the flight director system, can be used for pitch, roll and
heading hold. The autopilot will hold the pitch attitude existing at the moment of AP engagement and
the pitch attitude existing at the moment of disengagement of a vertical mode. PIT and ROL will be
annunciated for the basic modes.
Cessna Citation XLS - Instrumentation & Avionics
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