Specifications

SECTION III
INSTRUMENTATION AND AVIONICS
MODEL 560
The radio altimeter system interfaces with the data acquisition units (DAUs) and the optional ground
proximity warning system. The DAUs provide information to the integrated avionics computers (IACs)
which, in turn, provide the digital absolute altitude display In the PFDs, in the lower part of both attitude
director (ADI) displays. The digital altitude readout is green until the airplane descends below a set decision
height altitude, at which time the display becomes amber. The radio altimeter is in operation during the
entire flight, however, there is no altitude indication above an absolute altitude of 2500 feet. If the radio
altimeter is invalid, a red box with RA inside will appear instead of the digital read-out of altitude. The radio
altimeter also has an effect on the altitude tape in the PFD. A solid brown raster band will appear on the
altitude tape on the primary flight displays as the radio altitude drops below 550 feet. The brown band will
cover the lower half of the altitude tape when the airplane is on the ground. A yellow line will be drawn at
the intersection of the brown raster and the gray band of the latitude tape. There is no written information
displayed in the brown band.
There is also a radio altimeter decision height indication, which is a digital display located in the PFDs
in the lower right corner of the ADI display. The decision height is set to a predetermined altitude by
rotating the MINIMUMS knob located in the lower left corner of the PFD bezel controller. The decision
height is displayed in a window on the lower right side of the attitude director indicator display. When the
airplane descends below the selected altitude, an amber DH, enclosed in a white box, will appear in the
upper left side of the attitude director indicator display. The copilot's decision height is independent of the
pilot's, even though only one radio altimeter is installed. The decision height warning horn will sound only
when the airplane descends below the altitude selected in the decision height window on the pilot's attitude
director indicator (ADI) display. The decision height (DH) display is located on each ADI. A different
decision height can be set on each indicator, which will control the DH annunciator on that indicator only.
The different radio altitude indicators operate independently of each other, even though they are driven by
the same radio altimeter transceiver.
The radio altimeter can be functionally tested by selecting the Main 2/2 Menu on the applicable
multifunction display, which will show LRU TEST as a selection option. Press LRU TEST and RAD ALT
will appear as a submenu option; press RAD ALT and a box will appear around RAD ALT while it is being
held down, and the radio altimeter will test. On airplanes equipped with the standard Honeywell AA300
system, the display will indicate 100 feet and the DH annunciator shall not be displayed. On airplanes
having the Collins ALT-55 radio altimeter installation the display will indicate 50 feet. After the button is
released the actual altitude will be shown. If a decision height is set below the radio altimeter test altitude,
a chime will sound as the altitude comes back down through 100 feet (or 50 feet on Collins radio altimeter
installations) when the button is released and the amber DH will be annunciated in a box in the upper left
side of the altitude sphere. The radio altimeter test function is disabled after glideslope capture during an
ILS or MLS approach in which the autopilot or flight director is being used. Taxiing over accumulations of
ice and snow may cause radio altimeter fluctuations.
The system may be used in flight to monitor absolute altitude at any altitude within the range of the
altimeter. The MINIMUMS control on the PFD can be set to alert the pilot automatically whenever the
airplane reaches a preset altitude. The system may be used to display ground separation and climb
conditions during night or instrument takeoffs, as well as to indicate ground clearance during approaches.
The DH read-out may be extinguished by turning the MINIMUMS fully counterclockwise.
WEATHER RADAR
PRIMUS 660 COLORADAR
WARNING
ON THE PRIMUS 660 SERIES RADAR, THE AREA WITHIN 30 FEET OF AN
OPERATING WEATHER RADAR SYSTEM CONSTITUTES A HAZARDOUS AREA.
DO NOT OPERATE THE RADAR SYSTEM WITHIN 30 FEET OF PERSONNEL OR
FLAMMABLE OR EXPLOSIVE MATERIAL OR DURING FUELING OPERATIONS.
FOR GROUND OPERATION OF A RADAR SYSTEM, POSITION THE AIRPLANE
FACING AWAY FROM BUILDINGS OR LARGE METAL STRUCTURES THAT ARE
LIKELY TO REFLECT RADAR ENERGY BACK TO THE AIRPLANE.
I 3-66 Configuration AA 56OMB-01