Honeywell Primus 880 Manual

Printed in U.S.A. Pub. No. A28--1146--102--03 September 1996
Revised January 2006
Honeywell International Inc.
Commercial Electronic Systems
5353 W. Bell Rd.
Glendale, Arizona 85308--3912
U.S.A.
(CAGE 55939)
PRIMUSr880 Digital Weather
Radar System
Pilot’s Guide

PRIMUS
r
880
Digital
W
eather
Radar
System
A28-1146-102-00 Table of Contents
TC-1
Table of Contents
Section Page
1. INTRODUCTION 1-1.............................
2. SYSTEM CONFIGURATIONS 2-1.................
3. OPERATING CONTROLS 3-1....................
WI-880 Weather Radar Indicator Operation 3-1......
WC-880 Weather Radar Controller Operation 3-11....
WC-884 Weather Radar Controller Operation 3-20....
Hidden Modes 3-26...............................
Forced Standby Override 3-26...................
Roll Offset 3-27................................
Roll Gain 3-27.................................
Pitch Offset 3-27...............................
Pitch Gain 3-28................................
4. NORMAL OPERATION 4-1.......................
Preliminary Control Settings 4-1...................
Standby 4-4..................................
Radar Mode -Weather 4-4....................
Radar Mode -Ground Mapping 4-6.............
Test Mode 4-6................................
5. RADAR FACTS 5-1..............................
Radar Operation 5-1.............................
Tilt Management 5-5.............................
Stabilization 5-18.................................
Dynamic Error 5-18............................
Accelerative Error 5-18.........................
Pitch and Roll Trim Adjustments 5-19.............
Stabilization Precheck 5-21.....................
Roll stabilization check 5-25........................
Pitch offset adjustment 5-28........................
Roll gain adjustment 5-29..........................
Pitch gain adjustment 5-30.........................
Interpreting Weather Radar Images 5-31.............
Weather Display Calibration 5-35...................
Variable Gain Control 5-37.........................

PRIMUS r 880 Digital Weather Radar System
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Table of Contents
TC--2
Table of Contents (cont)
Section Page
5. RADAR FACTS (cont)
Rain Echo Attenuation Compensation Technique
(REACT) 5-37..................................
Shadowing 5-40...............................
Turbulence Probability 5-40.....................
Turbulence Detection Theory 5-42...............
Turbulence Detection Operation 5-45.............
Hail Size Probability 5-47.......................
Spotting Hail 5-48..............................
Azimuth Resolution 5-53........................
Radome 5-54....................................
Weather Avoidance 5-55...........................
Configurations of Individual Echoes (Northern
Hemisphere) 5-60............................
Line Configurations 5-65........................
Additional Hazards 5-68........................
Ground Mapping 5-69.............................
6. MAXIMUM PERMISSIBLE EXPOSURE LEVEL
(MPEL) 6-1....................................
7. IN--FLIGHT TROUBLESHOOTING 7--1.............
Test Mode With TEXT FAULTS Enabled 7-2.........
Fault Code and Text Fault Relationships 7-5.........
8. HONEYWELL PRODUCT SUPPORT 8-1..........
9. ABBREVIATIONS 9-1...........................
APPENDICES
A FEDERAL AVIATION ADMINISTRATION (FAA)
ADVISORY CIRCULARS A--1....................
Purpose A--1....................................
Cancellation A--1.................................
Related Reading Material A--1......................
Background A--2.................................
Precautions A--2.................................

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Table of Contents
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Table of Contents (cont)
A FEDERAL AVIATION ADMINISTRATION (FAA)
ADVISORY CIRCULARS (
CONT )
SUBJECT: THUNDERSTORMS A--4...............
Purpose A--4..................................
Related Reading Material A--4...................
General A--4..................................
Hazards A--4..................................
National Severe Storms Laboratory (NSSL)
Thunderstorm Research A--11..................
B ENHANCED GROUND--PROXIMITY WARNING
SYSTEM (EGPWS) B--1.........................
System Operation B--1............................
EGPWS Controls B--1..........................
Related EGPWS System Operation B--3..........
EGPWS Operation B--3........................
EGPWS Display B--4..........................
EGPWS Test B--6.............................
INDEX Index--1.............................................
List of Illustrations
Figure Page
2--1 PRIMUS
R
880 Configurations 2-2..................
2--2 Typical PRIMUS
R
880 Weather Radar
Components 2-5...............................
3--1 Typical PRIMUS
R
880 Digital Weather Radar
Display 3-1....................................
3--2 WI--880 Weather Radar Indicator Front Panel
View 3-2......................................
3--3 WI--880 Weather Radar Indicator Display Screen
Features 3-3...................................
3--4 WC--880 Weather Radar Controller Configurations 3-11.
3--5 WC--884 Weather Radar Controller 3-20.............
4--1 Indicator Test Pattern 120°Scan (WX), With TEXT
FAULT Enabled 4-2............................
4--2 EFIS Test Pattern (Typical) 120°Scan Shown
(WX) 4-3......................................
4--3 WI--880 Indicator Test Pattern With TEXT FAULT
Enabled 4-4...................................

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Table of Contents
TC--4
Table of Contents (cont)
List of Illustrations
(
cont
)
Figure Page
5--1 Positional Relationship of an Airplane and Storm
Cells Ahead as Displayed on Indicator 5-2.........
5--2 Antenna Beam Slicing Out Cross Section of Storm
During Horizontal Scan 5-3......................
5--3 Sea Returns 5-4.................................
5--4 Radar Beam Illumination High Altitude
12--Inch Radiator 5-5...........................
5--5 Radar Beam Illumination High Altitude
18--Inch Radiator 5-5...........................
5--6 Radar Beam Illumination Low Altitude
12--Inch Radiator 5-6...........................
5--7 Radar Beam Illumination Low Altitude
18--Inch Radiator 5-6...........................
5--8 Ideal Tilt Angle 5-11...............................
5--9 Earth’s Curvature 5-11............................
5--10 Convective Thunderstorms 5-12....................
5--11 Unaltered Tilt 5-12................................
5--12 Proper Tilt Technique 5-13.........................
5--13 Tilt Management With Heading Changes 5-13........
5--14 Fast Developing Thunderstorm 5-14.................
5--15 Low Altitude Tilt Management 5-14..................
5--16 Antenna Size and Impact on Tilt Management 5-15....
5--17 Rules of Thumb 5-15..............................
5--18 Manual Tilt at Low Altitudes 5-17....................
5--19 Symmetrical Ground Returns 5-22..................
5--20 Ground Return Indicating Misalignment
(Upper Right) 5-22...............................
5--21 Ground Return Indicating Misalignment
(Upper Left) 5-23................................
5--22 Roll Stabilization Inoperative 5-24...................
5--23 Roll Offset Adjustment Display -- Initial 5-26..........
5--24 Roll Offset Adjustment Display -- Final 5-27..........
5--25 Weather Radar Images 5-31.......................
5--26 Radar and Visual Cloud Mass 5-33..................
5--27 Squall Line 5-34..................................
5--28 REACT ON and OFF Indications 5-39...............
5--29 Probability of Turbulence Presence in a Weather
Target 5-41.....................................
5--30 Total Return Vector 5-44...........................
5--31 No Turbulence 5-44...............................

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Table of Contents
TC--5
Table of Contents (cont)
List of Illustrations
(
cont
)
Figure Page
5--32 Turbulent 5-45....................................
5--33 Weather Display With Turbulence 5-45..............
5--34 Turbulence Levels (From Airman’s Information
Manual) 5-47...................................
5--35 Hail Size Probability 5-48..........................
5--36 Rain Coming From Unseen Dry Hail 5-49............
5--37 Familiar Hailstorm Patterns 5-50....................
5--38 Overshooting a Storm 5-51........................
5--39 Short-- and Long--Blind Alley 5-52...................
5--40 Azimuth Resolution in Weather Modes 5-53..........
5--41 Weather Display 5-55.............................
5--42 Typical Hook Pattern 5-61.........................
5--43 V--Notch Echo, Pendant Shape 5-62................
5--44 The Classic Pendant Shape 5-63...................
5--45 Rain Gradients 5-64...............................
5--46 Crescent Shape 5-65..............................
5--47 Line Echo Wave Pattern (LEWP) 5-66...............
5--48 Bow--Shaped Line of Thunderstorms 5-67............
5--49 Ground Mapping Display 5-69......................
6--1 MPEL Boundary 6-1.............................
7--1 Fault Annunciation on Weather Indicator With TEXT
FAULT Fields 7-3..............................
7--2 Fault Code on EFIS Weather Display With TEXT
FAULTS Disabled 7-4...........................
7--3 Radar Indication With Text Fault Enabled
(On Ground) 7-4...............................
A--1 Schematic Cross Section of a Thunderstorm A--6.....
B--1 EHSI Display Over KPHX Airport With the
EGPWS Display B--5............................
B--2 EGPWS Test Display B--6.........................

PRIMUS r 880 Digital Weather Radar System
A28--1146--102--01
REV 1
Table of Contents
TC--6
Table of Contents (cont)
List of Tables
Table Page
2--1 Dual Control Mode Truth Table 2-3................
2--2 PRIMUS
R
880 Weather Radar Equipment List 2-4....
3--1 Rainfall Rate Color Coding 3-4...................
3--2 Target Alert Characteristics 3-7...................
3--3 Rainfall Rate Color Coding 3-13...................
3--4 WC--880 Controller Target Alert Characteristics 3-17...
3--5 WC--884 Controller Target Alert Characteristics 3-21...
3--6 Rainfall Rate Color Coding 3-24...................
4--1 PRIMUS
R
880 Power--Up Procedure 4-1..........
5--1 Approximate Tilt Setting for Minimal Ground Target
Display 12--Inch Radiator 5-8...................
5--2 Approximate Tilt Setting for Minimal Ground Target
Display 18--Inch Radiator 5-9...................
5--3 Approximate Tilt Setting for Minimal Ground Target
Display 24--Inch Radiator 5-10...................
5--4 Pitch and Roll Trim Adjustments Criteria 5-20........
5--5 Stabilization In Straight and Level Flight Check
Procedure 5-21................................
5--6 Stabilization in Turns Check Procedure 5-23........
5--7 In--flight Roll Offset Adjustment Procedure 5-25......
5--8 Pitch Offset Adjustment Procedure 5-28............
5--9 Roll Gain Adjustment 5-29........................
5--10 Pitch Gain Adjustment 5-30.......................
5--11 Display Levels Related to VIP Levels (Typical) 5-36..
5--12 Severe Weather Avoidance Procedures 5-60........
5--13 TILT Setting for Maximal Ground Target Display
12--Inch Radiator 5-70...........................
5--14 TILT Setting for Maximal Ground Target Display
18--Inch Radiator 5-71...........................
7--1 Fault Data Fields 7-3............................
7--2 Text Faults 7-5.................................
7--3 Pilot Messages 7-8.............................
B--1 EGPWS Obstacle Display Color Definitions B--4......

PRIMUS
r
880
Digital
W
eather
Radar
System
A28-1146-102-00 Introduction
1-1
1. Introduction
The PRIMUSR880 DigitalWeatherRadarSystemisalightweight,
X-band digitalradarwith alphanumerics designed forweatherdetection
(WX)and ground mapping (GMAP).
The primary purpose of the system is to detect storms along the
flightpath and give the pilot avisual indication in color of their rainfall
intensity and turbulence content. After proper evaluation, the pilot can
chart acourse to avoid these storm areas.
WARNING
THE SYSTEMPERFORMSTHEFUNCTIONSOF
WEATHER DETECTIONORGROUND MAPPING. ITSHOULD
NOTBEUSED NOR RELIED UPONFORPROXIMITY
WARNING OR ANTICOLLISIONPROTECTION.
In weather detection mode, storm intensity levels are displayed in
four bright colors contrasted against a deep black background.
Areas of very heavy rainfall appear in magenta, heavy rainfall in red,
less severe rainfall in yellow,moderate rainfall in green, and little or no
rainfall in black (background). Areas of detected turbulence appear in
soft white. The antenna sweep position indicator is ayellow bar.
Range marksand identifyingnumerics, displayedin contrastingcolors,
are provided to facilitate evaluation of storm cells.
Select the GMAP function to optimize system parameters to improve
resolution and enhance identification of small targets at short ranges.
The reflected signal from ground surfaces is displayed as magenta,
yellow,or cyan (most to least reflective).
NOTE: SectionV,RadarFacts,describesavarietyofradaroperating
topics. It is recommended that you read Section V,Radar
Facts, before learning the specific operational details of the
PRIMUSâ880 Digital Weather Radar System.

PRIMUS
r
880
Digital
W
eather
Radar
System
A28-1146-102-00
Introduction
1-2
Theradarindicatorisequippedwiththeuniversaldigitalinterface(UDI).
This feature expands the use of the radar indicator to display
information such as checklists, short and long range navigation
displays (when used with aHoneywell DATANAVsystem) and
electrical discharge data from Honeywell’sLSZ-850 Lightning Sensor
System (LSS).
NOTE: Refer to Honeywell Pub. 28-1146-54, LSZ-850 Lightning
Sensor System Pilot’sHandbook, for more information.

PRIMUS
r
880
Digital
W
eather
Radar
System
A28-1146-102-00 System Configurations
2-1
2. System Configurations
The PRIMUSâ880 Digital Weather Radar System can be operated in
many configurations to display weather or ground mappinginformation
on a radar indicator,electronic flight instrument system (EFIS) display,
multifunctiondisplay(MFD),oronacombinationofthesedisplays.The
various system configurations are summarized in the following
paragraphs and shown in figure 2-1.
NOTE: Other configurations are possible but not illustrated.
The stand-alone configuration consists of two units: receiver
transmitter antenna (RTA), and a dedicated radar indicator.In this
configuration,theradarindicatorcontainsallthecontrolstooperatethe
PRIMUSâ880 Digital Weather Radar System. Asingle or dual
HoneywellEFIScanbeaddedtothestand-aloneconfiguration.Insuch
acase the electronic horizontal situation indicator (EHSI) repeats the
data displayed on the radar indicator.System control remains with
the radar indicator.
The second system configuration uses an RTA, and single or dual
controllers. The single or dual EFIS is the radar display.Since there is
no radar indicator in this configuration, the radar system operating
controlsarelocatedonthecontroller.Withasinglecontroller,allcockpit
radar displays are identical.
The dual configuration gives the appearance of having two radar
systems on the aircraft. In the dual configuration, the pilot and copilot
each select independent radar mode, range, tilt, and gain settings for
display on their respective display.The dual configuration time shares
theRTA.Ontheright-to-leftantennascan, thesystemswitchestothe
mode, range, tilt, and gain selected by the left controller and updates
the left display.On the reverse antenna scan, the system switches to
the mode, range, tilt, and gain setting selected by the right controller
and updates the right display.Either controller can be slaved to the
other controller to show identical images on both sides of the cockpit.
NOTE: When WAIT,SECTOR SCAN, or FORCED STANDBY are
activated, the radar operates as if in single controller
configuration. This is an exception to the ability of each pilot
to independently select modes.

PRIMUS
r
880
Digital
W
eather
Radar
System
A28-1146-102-00
System Configurations
2-2
STAND-ALONE CONFIGURATION
SINGLE OR DUAL EFIS OPTION
RTA
WU-880 INDICATOR WI-880
EFIS ONLYCONFIGURATION
RTA
WU-880 CONTROLLER WC-880
SINGLE OR DUAL EFIS OPTIONAL
2ND CONTROLLER
EFIS /MFD CONFIGURATION
RTA
WU-880 CONTROLLER WC-880
MFD AND
SINGLE OR DUAL EFIS
OPTIONAL
2ND CONTROLLER
AD-46690-R2@
TRB STAB TGT SECT
+
-
TILTSLVRADARGAIN
RCTWX
SBY GMAP
FP
TST
OFF
PULL
VAR
MAXMIN
PULL
ACT
TRB STAB TGT SECT
+
-
TILTSLVRADARGAIN
RCTWX
SBY GMAP
FP
TST
OFF
PULL
VAR
MAXMIN
PULL
ACT
TRB STAB TGT SECT
+
-
TILTSLVRADARGAIN
RCTWX
SBY GMAP
FP
TST
OFF
PULL
VAR
MAXMIN
PULL
ACT
TRB STAB TGT SECT
+
-
TILTSLVRADARGAIN
RCTWX
SBY GMAP
FP
TST
OFF
PULL
VAR
MAXMIN
PULL
ACT
PRIMUSâ880 Configurations
Figure 2-1

PRIMUS
r
880
Digital
W
eather
Radar
System
A28-1146-102-00 System Configurations
2-3
The third system configuration is similar to the second except that a
Honeywell multifunction display (MFD) system is added. As before,
single ordual controllerscan beused. Whenasinglecontroller isused,
all displays show the same radar data. Dual controllers are used to
operate in the dual mode. The MFD can be slaved to either controller
toduplicatethedata displayedontheselectedside.Table2-1isatruth
table for dual control modes.
Left
Controller
Mode
Right
Controller
Mode Left Side
(NOTE 1) Right Side (NOTE 1) RTA Mode
OFF OFF OFF OFF OFF
OFF Standby ”SLV”
Standby Standby Standby
Standby OFF Standby ”SLV”
Standby Standby
OFF ON ”SLV”ON ON ON
ON OFF ON ”SLV”ON ON
Standby ON Standby/
2ON/2 ON
ON Standby ON/2 Standby/2 ON
ON ON ON/2 ON/2 ON
Standby Standby Standby Standby Standby
Dual Control Mode Truth Table
Table 2-1

PRIMUS r 880 Digital Weather Radar System
A28--1146--102--03
REV 3
System Configurations
2-4
NOTES: 1. ON is used to indicate any selected radar mode.
2. “SLV” means that displayed data is controlled by
opposite side controller.
3. XXX/2 means that display is controlled by appropriate
on--side control for the antenna sweep direction
associated with that control. (/2 implies two controllers
are on.)
4. In standby, the RTA is centered in azimuth with 15_
upward tilt. Video data is suppressed. The transmitter
is inhibited.
5. The MFD, if used, can repeat either left-- or right--side
data, depending upon external switch selection.
Equipment covered in this guide is listed in table 2--2 and shown in
figure 2--2.
Model Unit Part No.
Cockpit Mounted Options
WI--880 Weather Radar Indicator 7007700--401/402/
403/404
WC--880 Weather Radar Controller 7008471--4XX
WC--884 Weather Radar Controller 7006921--815/816
Remote Mounted Equipment
WU--880 Receiver Transmitter Antenna 7021450--801
NOTE: Typically, either the indicator or one of the remote
controllers (one or two) is installed.
PRIMUS
R
880 Weather Radar Equipment List
Table 2--2

PRIMUS
r
880
Digital
W
eather
Radar
System
A28-1146-102-00 System Configurations
2-5/(2-6 blank)
WC-884 CONTROLLER
WC-880 CONTROLLERWI-880 INDICATOR
WU-880 RTA
AD-46691@
Typical PRIMUSâ880 Weather Radar Components
Figure 2-2

PRIMUS
r
880
Digital
W
eather
Radar
System
A28-1146-102-00 Operating Controls
3-1
3. Operating Controls
WI-880 WEATHER RADAR INDICATOR OPERATION
Allcontrolsusedtooperate thesystem displayshown infigure 3-1,are
located on the WI-880Weather Radar Indicator front panel. There are
three basic controllers that are described in this section, they are (in
order of description):
DWI-880 Weather Radar Indicator
DWC-880 Weather Radar Controller
DWC-884 Weather Radar Controller.
AZ
AUTO
TILT50
40
30
20
10
+1.0
21 3 4 T
Typical PRIMUSâ880 Digital
Weather Radar Display
Figure 3-1
The controls and display features of the WI-880 Weather Radar
Indicator are indexed and identified in figure 3-2.Brightness levels for
all legends and controls on the indicator are controlled by the dimming
bus for the aircraft panel.

PRIMUS
r
880
Digital
W
eather
Radar
System
A28-1146-102-00
Operating Controls
3-2
AD-46693-R1@
RCT
TGT
AZ
SCT
RANGE
GMAP
WX FP
TST
SBY
OFF
GAIN
MIN MAX
PULL
VAR
PULL
ACT
TILT+
-
BRT
STB
TRB 7
8
9
10
11
2
1
3
4
5
6
12
10
BRT
OFF CLR
TST
SBY LX
WI-880 Weather Radar Indicator Front Panel View
Figure 3-2
1Display Area
Seefigure3-3andtheassociatedtextwhichexplainsthealphanumeric
display.

PRIMUS
r
880
Digital
W
eather
Radar
System
A28-1146-102-00 Operating Controls
3-3
AD-46694-R2@
T
TGT
1234T
VAR!
1 2 3
VAR
1234T
VAR!
TARGET/TARGET ALERT:
ARM (GREEN)
ALERT(YELLOW INVERTED VIDEO)
TILTANGLE ALTITUDE
COMPENSATED
TILT(ACT)
ANNUNCIATION
RANGE RING
MARKERS
(120-DEGREE
SCAN SHOWN)
WX CALIBRATED GAIN
WX VARIABLE GAIN
GMAP CALIBRATED GAIN
GMAP VARIABLE GAIN
WX/T CALIBRATED GAIN
WX/T VAR
COLOR BAR:
MESSAGES ARE LISTED
IN PRIORITY ORDER.
NOTE:
STBY
FSBY
WAIT
TEST
WX
WX/T
FLTPLN
GMAP
MODE:
REACT:RCT
NOTE FAIL
STB A
WI-880 Weather Radar Indicator Display Screen Features
Figure 3-3
2Function Switch
Arotary switch used to select the following functions:
DOFF-This position turns offthe radar system.
DSBY (Standby) -This position places the radar system in standby,
aready state, with the antenna scan stopped, the transmitter
inhibited, and the display memory erased. STBY,in white, is shown
in the mode field.
If SBY is selected before the initial RTAwarmup period is complete
(approximately 90 seconds), the white WAIT legend is shown in
the mode field. When warmup is complete the system changes the
mode field to STBY.
DWX (Weather) -This position selects the WX mode of operation.
When WX is selected, the system is fully operational and all internal
parameters are set for enroute weather detection. The
alphanumerics are white and WX is shown in the mode field.

PRIMUS
r
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Digital
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Radar
System
A28-1146-102-00
Operating Controls
3-4
If WX is selected before the initial RTAwarmup period is over
(approximately 90 seconds), the white WAIT legend is displayed
in the mode field. In wait mode, the transmitter and antenna scan
are inhibited and the display memory is erased. When the warmup
is complete, the system automatically switches to the WX mode.
The system, in preset gain, is calibrated as listed in table 4-1.
Rainfall Rate Color
in/hr mm/hr
.04-.16 1-4Green
.16-.47 4-12 Yellow
.47-2 12-50 Red
>2>5 0Magenta
Rainfall Rate Color Coding
Table 3-1
DGMAP (Ground Mapping) -The GMAP position puts the radar
system in the ground mapping mode. The system is fully
operational and all parameters are set to enhance returns from
ground targets.
NOTE: REACT,TGT,orTURBmodesare notselectableinGMAP.
WARNING
WEATHER TYPE TARGETS ARE NOT CALIBRATED WHEN
THE RADAR IS IN THE GMAP MODE. BECAUSE OF THIS, DO
NOT USE THE GMAP MODE FOR WEATHER DETECTION.
As aconstant reminder that GMAP is selected, the alphanumerics
are changed to green, the GMAP legend is shown in the mode field,
and the color scheme is changed to cyan, yellow,and magenta.
Cyan represents the least reflective return, yellow is amoderate
return, and magenta is astrong return.
If GMAP is selected before the initial RTAwarmup period is
complete, the white WAIT legend is shown in the mode field. In wait
mode, the transmitter and antenna scan are inhibited and the
memory is erased. When the warmup period is complete, the
system automatically switches to the GMAP mode.
DFP(FlightPlan)-TheFPpositionputstheradarsystemintheflight
plan mode, which clears the screen of radar data so ancillary data
can be displayed. Examples of this data are:

PRIMUS r 880 Digital Weather Radar System
A28--1146--102--03
REV 3 3-5
Operating Controls
DFP (Flight Plan) -- The FP position puts the radar system in the flight
plan mode, which clears the screen of radar data so ancillary data
can be displayed. Examples of this data are:
—Navigation displays
—Electrical discharge (lightning) data.
NOTE: In the FP mode, the radar RTA is put in standby, the
alphanumerics are changed to cyan, and the FLTPLN
legend is shown in the mode field.
The target (TGT) alert mode can be used in the FP mode. With
target alert on and the FP mode selected, the target alert armed
annunciation (green TGT) is displayed. The RTA searches for a
hazardous target from 5 to 55 miles and ±7.5°of the aircraft heading.
No radar targets are displayed. If a hazardous target is detected,
the target alert armed annunciation switches to the alert
annunciation (yellow TGT). This advises the pilot that a hazardous
target is in his flightpath and the WX mode should be selected to
view it.
NOTE: The TGT function is inoperative when a checklist is
displayed.
DTST (Test) -- The TST position selects the radar test mode. A
special test pattern is displayed to verify system operation. The
TEST legend is shown in the mode field. Refer to Section 4, Normal
Operations, for a description of the test pattern.
WARNING
UNLESS THE SYSTEM IS IN FORCED STANDBY, THE
TRANSMITTER IS ON AND RADIATING X--BAND
MICROWAVE ENERGY IN TEST MODE. REFER TO SECTION 6,
MAXIMUM PERMISSIBLE EXPOSURE LEVEL (MPEL), AND THE
APPENDIX, FEDERAL AVIATION ADMINISTRATION (FAA)
ADVISORY CIRCULARS, TO PREVENT POSSIBLE HUMAN BODY
DAMAGE.
FSBY (Forced Standby)
FSBY is an automatic, nonselectable radar mode. As an installation
option, the indicator can be wired to the weight--on--wheels (WOW)
squat switch. When wired, the RTA is in the FSBY mode when the
aircraft is on the ground. In FSBY mode, the transmitter and antenna
scan are both inhibited, the display memory is erased, and the FSBY
legend is displayed in the mode field. When in the FSBY mode,
pushing the STAB button 4 times within 3 seconds, restores normal
operation.