Specifications

SECTION III
MODEL 560 INSTRUMENTATION AND AVIONICS
PROGRAMMING
Programming is possible when a VOR station is tuned, lock-on of azimuth and DME occurs, and the
waypoint desired is within selectable parameters, or when FMS navigation is in use and the next waypoint is
used to define the VNAV problem. Arming of the VNAV to any waypoint consists of selection of the desired
waypoint, and selection of waypoint data which will enable the flight director computer to compute a viable
VNAV problem.
Using short range NAV, when a VORTAC station is tuned, identified, and lock-on is achieved, the
VNAV selections can be made. If TO or FROM (FR) bias is required the second button from the left on the
bezel of the multifunction display (MFD) is pressed, which will result in display of a box into which may be
set the TO or FR bias by turning the left knob on the MFD. TO or FROM is selected before the distance
selection is made by toggling the button, resulting in annunciation of TO or FR above the selection window.
Station elevation (STA EL) of the VORTAC station in use is then set by pressing the second button from
the right and setting the correct elevation, to the nearest 100 feet, into the window above it. Set the
desired altitude in the preselect window. The VNAV problem is now established, and VNAV may be
selected. If long range NAV is used the problem is similarly defined; FMS must be selected on the DC-550,
which will result in long range data being displayed on the menu at the bottom of the MFD display, and
therefore being selected by the respective knobs discussed above. If FMS is being used, station elevation
(STA EL) is not required.
If a valid problem has been defined, the computed angle will be displayed on the MFD VNAV menu
located at the bottom right of the MFD display. A VNAV problem is valid only if the vertical angle is less
than +/- 6°. The flight director computer will continually compute the vertical angle based on aircraft
position and update the display on the vertical path indicator on the PFD. If the pilot desires he can rotate
the VNAV set knob and increase the vertical angle up to a maximum of 6°, which will create a vertical path
intercept point some distance ahead of the aircraft. Once a valid VNAV problem has been defined, the pilot
can select the VNAV mode on the MS-550 Mode Selector. VNAV mode will, however, not activate until it is
selected, or selection is affirmed, by a pilot action.
If the pilot has selected an intercept point ahead of the airplane by increasing the vertical angle before
selecting the VNAV mode, the flight director will remain in the previous mode until the appropriate time.
Approximately one minute prior to the flare point the altitude alert horn will sound two short beeps. The
vertical track alert (VTA) will flash on the PFD and the VNAV annunciator will flash on the MS-560 Mode
Selector. A pilot action is required before the VNAV capture phase can commence. The pilot must press
the flashing VNAV button on the mode selector before it stops flashing, to allow the mode to capture. Once
the button is pressed, the annunciation in the mode selector will stop flashing and remain on, as with the
VTA annunciator on the PFD. If the pilot wishes to cancel the mode he can press the VNAV button twice
on the mode selector when it flashes, or he can do nothing and wait for the flashing to stop, at which time
the mode will automatically disengage.
When the VNAV mode is engaged, the VNAV parameters are frozen. This includes STA EL, TO,
FROM, and VANG; changing the ALT SEL value will also cause the mode to drop out. The pilot may still
view any of these parameters but the set knob will have no affect. After the airplane has leveled off at the
waypoint altitude and transitioned into altitude hold mode the VNAV parameters for the current problem are
erased.
If the pilot deselects the VNAV mode by pressing the VNAV button, the flight director cancels the
mode but the data for the current waypoint are retained. The angle from the present position to the
waypoint will still be tracked but the parameters will no longer be frozen and can be modified as desired by
the pilot. The VNAV mode can be reselected as long as the problem remains valid.
ALTITUDE ALERTING SYSTEM
The altitude alerting system is automatically engaged in conjunction with the altitude preselect mode
(ASEL) and the vertical navigation (VNAV) mode. The desired altitude is set into the system for use of the
VNAV or ASEL modes. In both cases the altitude is set into the lower right corner of the MFD with the right
knob on the MFD bezel. The desired flight director mode which is to be used to reach the designated
altitude is then selected on the flight director/autopilot mode control panel. Refer to Altitude Hold and
Altitude Preselect, below. If the pilot does not desire to select a flight director mode, the airplane can be
flown manually and the altitude alerting system will still provide the appropriate annunciations.
I 56OMB-01 Configuration AA 3-41