Honeywell_Weather_Radio

PRIMUSr 880 Digital Weather Radar System

1.Introduction

The PRIMUSR 880 Digital Weather Radar System is a lightweight, X- band digital radar with alphanumerics designed for weather detection (WX) and ground mapping (GMAP).

The primary purpose of the system is to detect storms along the flightpath and give the pilot a visual indication in color of their rainfall intensity and turbulence content. After proper evaluation, the pilot can chart a course to avoid these storm areas.

WARNING

WARNING OR ANTICOLLISION PROTECTION.

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 a yellow bar.

Range marks and identifying numerics, displayed in contrasting colors, 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: Section V, Radar Facts, describes a variety of radar operating topics. It is recommended that you read Section V, Radar Facts, before learning the specific operational details of the PRIMUS?? 880 Digital Weather Radar System.

PRIMUSr 880 Digital Weather Radar System

2.System Configurations

The PRIMUS?? 880 Digital Weather Radar System can be operated in many configurations to display weather or ground mapping information on a radar indicator, electronic flight instrument system (EFIS) display, multifunction display (MFD), or on a combination of these displays. 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, the radar indicator contains all the controls to operate the PRIMUS?? 880 Digital Weather Radar System. A single or dual Honeywell EFIS can be added to the stand- alone configuration. In such a case 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 controls are located on the controller. With a single controller, all cockpit 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 the RTA. On the right- to- leftantenna scan, the system switches to the 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.

PRIMUSr 880 Digital Weather Radar System

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.

NOTE: Typically, either the indicator or one of the remote controllers (one or two) is installed.

PRIMUSR 880 Weather Radar Equipment List

Table 2--2

PRIMUSr 880 Digital Weather Radar System

3.Operating Controls

WI- 880 WEATHER RADAR INDICATOR OPERATION

All controls used to operate the system display shown in figure 3- 1, are located on the WI- 880 Weather Radar Indicator front panel. There are three basic controllers that are described in this section, they are (in order of description):

D WI- 880 Weather Radar Indicator

D WC- 880 Weather Radar Controller

D WC- 884 Weather Radar Controller.

Typical PRIMUS?? 880 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.

PRIMUSr 880 Digital Weather Radar System

TARGET/TARGET ALERT:

T ARM (GREEN)

TGT ALERT (YELLOW INVERTED VIDEO)

WI- 880 Weather Radar Indicator Display Screen Features

Figure 3- 3

2 Function Switch

A rotary switch used to select the following functions:

D OFF- This position turns off the radar system.

D SBY (Standby) - This position places the radar system in standby, a ready 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 RTA warmup 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.

D WX (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.

PRIMUSr 880 Digital Weather Radar System

If WX is selected before the initial RTA warmup 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 Coding

Table 3- 1

D GMAP (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, or TURB modes are not selectable in GMAP.

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 a constant 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 a moderate

return, and magenta is a strong return.

If GMAP is selected before the initial RTA warmup 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.

D FP (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:

PRIMUSr 880 Digital Weather Radar System

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.

PRIMUSr 880 Digital Weather Radar System

WARNING

FORCED STANDBY MODE MUST BE VERIFIED BY THE OPERATOR

TO ENSURE SAFETY FOR GROUND PERSONNEL.

3 TGT (Target)

The TGT button is an alternate- action switch that enables and disables the radar target alert feature. Target alert is selectable in all but the 300- mile range. When selected, target alert monitors beyond the selected range and 7.5?? on each side of the aircraft heading. If a return with target alert characteristics is detected in the monitored area, the target alert legend changes from the green T armed condition to the yellow TGT warning condition. (See the target alert characteristics in table 3- 2 for a target description.) These annunciations advise the pilot of potentially hazardous targets directly in front of the aircraft that are outside the selected range. When a yellow warning is received, the pilot should select longer ranges to view the questionable target. (Note that target alert is inactive within the selected range.)

Selecting target alert forces the system to preset gain. Target alert can be selected only in the WX or FP modes.

NOTE: In order to activate the target alert warning, the target must have the depth and range characteristics described in table 3- 2.

PRIMUSr 880 Digital Weather Radar System

Target Alert Characteristics

Table 3- 2

4RCT (Rain Echo Attenuation Compensation Technique (REACT))

The RCT switch is an alternate- action switch that enables and disables REACT.

The REACT circuitry compensates for attenuation of the radar signal as it passes through rainfall. The cyan field indicates areas where further compensation is not possible. Any target detected within the cyan field cannot be calibrated and should be considered dangerous. All targets in the cyan field are displayed as fourth level precipitation, magenta.

REACT is available in the WX mode only and selecting REACT forces the system to preset gain. When engaged, the white RCT legend is displayed in the REACT field.

NOTES: 1. REACT???S three main functions (attenuation compensation, cyan field, and forcing targets to magenta) are switched on and off with the RCT switch.

2.Refer to Section 5, Radar Facts, for a description of

REACT.

5 STB (Stabilization)

The STB button toggles pitch and roll stabilization ON and OFF. It is also used with the STB adjust mode and to override forced standby.

The radar antenna is normally attitude stabilized. It automatically compensates for roll and pitch maneuvers (refer to Section 5, Radar Facts, for a description of stabilization). The STB OFF annunciator is displayed on the screen.

PRIMUSr 880 Digital Weather Radar System

6 TRB (Turbulence)

The TRB switch is used to select the turbulence detection mode of operation. The TRB mode can only be selected if the FUNCTION switch is in the WX position and the selected range is 50 miles or less. The weather/turbulence mode is annunciated in the mode field with the WX/T legend. Areas of moderate or greater turbulence are shown in soft white. The turbulence threshold is five meters per second.

WARNINGS

1.TURBULENCE CAN ONLY BE DETECTED WITHIN AREAS OF

RAINFALL. THE PRIMUSR 880 DIGITAL WEATHER RADAR

SYSTEM CANNOT DETECT CLEAR AIR TURBULENCE.

2.UNDETECTED TURBULENCE CAN EXIST WITHIN ANY

STORM CELL. REFER TO SECTION 5, RADAR FACTS, OF THIS

GUIDE FOR ADDITIONAL INFORMATION.

Selecting the 100--, 200--, or 300--mile range turns off turbulence detection. The /T is deleted from the mode annunciation. Subsequently selecting ranges of 50 miles or less re--engages turbulence detection.

A description of the turbulence detection capabilities and limitations is given in Section 5 , Radar Facts, of this guide.

7 RANGE

The RANGE buttons are two momentary--contact buttons used to select the operating range of the radar. The range selections are from 5 to 300 NM full scale. In FP mode, additional ranges of 500 and 1000 NM are available. The up arrow selects increasing ranges, and the down arrow selects decreasing ranges. Each of the five range rings on the display has an associated marker that annunciates its range.

8 AZ (Azimuth)

The AZ button is an alternate--action switch that enables and disables the electronic azimuth marks. When enabled, azimuth marks at 30_ intervals are displayed. The azimuth marks are the same color as the other alphanumerics.

9 SCT (Scan Sector)

PRIMUSr 880 Digital Weather Radar System

10 BRT (Brightness) or BRT/LSS (Lightning Sensor System)

The BRT knob is a single- turn control that adjusts the brightness of the display. Clockwise (cw) rotation increases display brightness and counterclockwise (ccw) rotation decreases brightness.

An optional BRT/LSS four- position rotary switch selects the separate LSZ- 850 Lightning Sensor System (LSS) operating modes and the brightness control on some models. Its LSS control switch positions are as follows:

D OFF - This position removes all power from the LSS.

DSBY (Standby) - This position inhibits the display of LSS data, but the system accumulates data in this mode.

DLX (Lightning Sensor System) - In this position the LSS is fully operational and data is being displayed on the indicator.

D CLR/TST (Clear/Test) - In this position accumulated data is cleared from the memory of the LSS. After 3 seconds the test mode is initiated in the LSS. Refer to the LSZ- 850 Lightning Sensor System Pilot???s Handbook, for a detailed description of LSS operation.

11 TILT

The TILT knob is a rotary control that is used to select the tilt angle of the antenna beam with relation to the horizon. CW rotation tilts beam upward to +15_; ccw rotation tilts beam downward to - 15_.

A digital readout of the antenna tilt angle is displayed on the CRT, with 0.5_ resolution.

D PULL ACT (Altitude Compensated Tilt) Function - When the TILT control knob is pulled out, the system engages the ACT. In ACT the antenna tilt is automatically adjusted with regard to the selected range and barometric altitude. The antenna tilt automatically readjusts with changes in altitude and/or selected range. In ACT, the

tilt control can fine tune the autotilt setting by ??2??.

ACT is annunciated with an A following the digital tilt readout. The digital tilt readout always shows the commanded tilt of the antenna regardless of the tilt command source (ACT command or manual tilt

command).

WARNINGS

1.TO AVOID FLYING UNDER OR OVER STORMS,

FREQUENTLY SELECT MANUAL TILT TO SCAN BOTH

ABOVE AND BELOW YOUR FLIGHT LEVEL.

2.ALWAYS USE MANUAL TILT FOR WEATHER ANALYSIS.

PRIMUSr 880 Digital Weather Radar System

12 GAIN

The GAIN knob is a single- turn rotary control and push/pull switch that is used to control the receiver gain. Push in on the GAIN switch to enter the system into the preset calibrated gain mode. Calibrated gain is the normal mode and is used for weather avoidance. In calibrated gain, the rotary portion of the GAIN control does nothing. In calibrated gain, the color bar legend is labeled 1,2,3,4 in WX mode or 1,2,3 in GMAP mode.

Pull out on the GAIN switch to enter the system into the variable gain mode with VAR displayed in the color bar. Variable gain is useful for additional weather analysis and for ground mapping. In WX mode, variable gain can increase receiver sensitivity over the calibrated level to show very weak targets or it can be reduced below the calibrated level to eliminate weak returns.

WARNING

HAZARDOUS TARGETS MAY BE ELIMINATED FROM THE DIS-

PLAY WITH LOW SETTINGS OF VARIABLE GAIN.

In the GMAP mode, variable gain is used to reduce the level of the typically very strong returns from ground targets.

Minimum gain is with the control at its full ccw position. Gain increases as the control is rotated cw from full ccw . At full cw position, the gain is at maximum.

In variable gain, the color bar legend contains the variable gain (VAR) annunciation. Selecting RCT or TGT forces the system into calibrated gain.

PRIMUSr 880 Digital Weather Radar System

1 RADAR

This rotary switch is used to select one of the following functions.

D OFF - This position turns the radar system off.

D SBY (Standby) - This position places the radar system in standby; a ready state, with the antenna scan stopped, the transmitter inhibited, and the display memory erased. STBY is displayed on the

EFIS/MFD.

D WX (Weather) - This position selects the weather detection mode. The system is fully operational and all internal parameters are set

for enroute weather detection.

If WX is selected before the initial RTA warmup period is complete (approximately 45 to 90 seconds), the WAIT legend is displayed on the EFIS/MFD. 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 described in table 3- 3.

Rainfall Rate Color Coding

Table 3- 3

DRCT (Rain Echo Attenuation Compensation Technique) - This switch position turns on RCT.

precipitation, magenta.

RCT is a submode of the WX mode and selecting RCT forces the system to preset gain. When RCT is selected, the RCT legend is

displayed on the EFIS/MFD.

PRIMUSr 880 Digital Weather Radar System

NOTES: 1. REACT???s three functions (attenuation compensation, cyan field, and forcing targets to magenta) are switched on and off with the RCT

switch.

2.Refer to Section 5, Radar Facts, for a description of REACT.

D GMAP (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, or TRB modes are not selectable in GMAP.

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 a constant reminder that GMAP is selected, the alphanumerics are changed to green, the GMAP legend is displayed in the mode field, and the color scheme is changed to cyan, yellow, and magenta. Cyan represents the least reflective return, yellow is a

moderate return, and magenta is a strong return.

If GMAP is selected before the initial RTA warmup period is complete (approximately 45 to 90 seconds), the white WAIT legend is displayed 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.

D FP (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 displayed in the mode field.

PRIMUSr 880 Digital Weather Radar System

The target 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 degrees of dead ahead. No radar targets are displayed. If a hazardous target is detected, the target alert armed annunciation switches to the alert annunciation (amber TGT). This advises the pilot that a hazardous target is in his flightpath and he

should select the WX mode to view it.

NOTE: When displaying checklist, the TGT function is inoperative.

D TST (Test) - The TST position selects the radar test mode. A special test pattern is displayed to verify system operation. The TEST legend is displayed 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 TRANSMIT-

TER IS ON AND RADIATING X- BAND MICROWAVE ENERGY IN

TEST MODE. REFER TO SECTION 6, MAXIMUM PERMISSIBLE

EXPOSURE LEVEL (MPEL).

D 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 in 3 seconds restores normal operation.

The FSBY mode is a safety feature that inhibits the transmitter on the ground to eliminate the X- Band microwave radiation hazard. Refer to

Section 6, Maximum Permissible Exposure Level (MPEL).

WARNING

FORCED STANDBY MODE MUST BE VERIFIED BY THE OPERA-

TOR TO ENSURE SAFETY FOR GROUND PERSONNEL.

In installations with two radar controllers, it is only necessary to override forced standby from one controller.

If either controller is returned to standby mode while weight is on wheels, the system returns to the forced standby mode.

PRIMUSr 880 Digital Weather Radar System

2 TILT

The TILT switch is a rotary control that is used to select the tilt angle of antenna beam with relation to the horizon. CW rotation tilts beam upward 0_ to 15_; ccw rotation tilts beam downward 0_ to - 15_. The range between +5_ and - 5_ is expanded for ease of setting. A digital readout of the antenna tilt angle is displayed on the EFIS.

D PULL ACT (Altitude Compensated Tilt) Function - When the TILT control knob is pulled out, the system engages the ACT (option). In ACT , the antenna tilt is automatically adjusted with regard to the selected range and barometric altitude. The antenna tilt automatically readjusts with changes in altitude and/or selected

range. In ACT, the tilt control can fine tune the tilt setting by ??2??.

command).

WARNINGS

1.TO AVOID FLYING UNDER OR OVER STORMS,

FREQUENTLY SELECT MANUAL TILT TO SCAN BOTH

ABOVE AND BELOW YOUR FLIGHT LEVEL.

2.ALWAYS USE MANUAL TILT FOR WEATHER ANALYSIS.

3 SECT (Scan Sector)

The SECT switch is an alternate- action button that is used to select either the normal 12 looks/minute 120_ scan or the faster update 24 looks/minute 60_ sector scan.

4 TGT (Target)

The TGT switch is an alternate- action, button that enables and disables the radar target alert feature. Target alert is selectable in all but the 300 mile range. When selected, target alert monitors beyond the selected range and 7.5_ on each side of the aircraft heading. If a return with certain characteristics is detected in the monitored area, the target alert changes from the green armed condition to the yellow TGT warning condition. This annunciation advises the pilot that a potentially hazardous target lies directly in front and outside of the selected range. When this warning is received, the pilot should select longer ranges to view the questionable target. Note that target alert is inactive within the selected range.

PRIMUSr 880 Digital Weather Radar System

Selecting target alert forces the system to preset gain. Target alert can only be selected in the WX and FP modes.

In order to activate target alert, the target must have the depth and range characteristics described in table 3- 4:

WC- 880 Controller Target Alert Characteristics

Table 3- 4

5 STB (Stabilization)

The STB button turns the pitch and roll stability ON and OFF. It is also used with the STB adjust mode and to override forced standby.

NOTE: Some controllers annunciate OFF when stabilization is OFF.

6 TRB (Turbulence Detection)

TRB is a switch used to select the turbulence detection mode of operation. The TRB mode can only be selected if the FUNCTION switch is in the WX or RCT positions and the selected range is 50 miles or less. The weather/turbulence mode is annunciated in the mode field with the WX/T legend. Areas of at least moderate turbulence are shown in soft white. The turbulence threshold is five meters per second.

PRIMUSr 880 Digital Weather Radar System

WARNINGS

1.TURBULENCE CAN ONLY BE DETECTED WITHIN AREAS OF

RAINFALL. THE PRIMUSR 880 DIGITAL WEATHER RADAR

SYSTEM CANNOT DETECT CLEAR AIR TURBULENCE.

2.UNDETECTED TURBULENCE CAN EXIST WITHIN ANY

STORM CELL. REFER TO SECTION 5, RADAR FACTS, OF THIS

GUIDE FOR ADDITIONAL INFORMATION.

Selecting the 100, 200, or 300 mile range turns off the turbulence detection. The /T is deleted from the mode annunciation and variable gain is engaged if previously selected. Subsequent selection of ranges of 50 miles or less re--engages turbulence detection.

A description of the turbulence detection capabilities and limitations of this radar system is given in Section 5, Radar Facts, of this guide.

7 RANGE

The RANGE switches are two momentary contact buttons that are used to select the operating range of the radar (and LSS if installed). The system permits selection of ranges in WX mode from 5 to 300 NM full scale. In the flight plan (FPLN) mode, additional ranges of 500 and 1000 miles are permitted. The up arrow selects increasing ranges, while the down arrow selects decreasing ranges. One--half the selected range is annunciated at the one--half scale range mark on the EHSI.

NOTE: Some Integrated avionics systems incorporate radar range with the map display range control on a MFD/ND display.

8 GAIN

The GAIN is a single turn rotary control and push/pull switch that is used to control the receiver gain. When the GAIN switch is pushed, the system enters the preset, calibrated gain mode. Calibrated gain is the normal mode and is used for weather avoidance. In calibrated gain, the rotary portion of the GAIN control does nothing.

When the GAIN switch is pulled out, the system enters the variable gain mode. Variable gain is useful for additional weather analysis and for ground mapping. In WX mode, variable gain can increase receiver sensitivity over the calibrated level to show weak targets or it can be reduced below the calibrated level to eliminate weak returns.

PRIMUSr 880 Digital Weather Radar System

WARNING

LOW VARIABLE GAIN SETTINGS CAN ELIMINATE HAZARDOUS

TARGETS FROM THE DISPLAY.

In GMAP mode, variable gain is used to reduce the level of strong returns from ground targets.

Minimum gain is attained with the control at its full ccw position. Gain increases as the control is rotated in a cw direction from full ccw at full cw position, the gain is at maximum.

The VAR! legend annunciates variable gain. Selecting RCT or TGT forces the system into calibrated gain.

9 SLV (Slave)

The SLV annunciator is only used in dual controller installations. With dual controllers, one controller can be slaved to the other by selecting OFF on that controller only, with the RADAR mode switch. This slaved condition is annunciated with the SLV annunciator.

In the slaved condition, both controllers must be off before the radar system turns off.

10 LSS (Lightning Sensor System) (Option)

The LSS switch is an optional four- position rotary switch that selects the LSS operating modes described below:

D OFF - In this position all power is removed from the LSS.

DSBY - In this position the display of LSS data is inhibited, but the LSS still accumulates data.

DLX - In this position the LSS is fully operational and it displays LSS data on the indicator.

D CLR/TST - In this position, accumulated data is cleared from the memory of the LSS. After 3 seconds the test mode is initiated in the

LSS.

PRIMUSr 880 Digital Weather Radar System

WC- 884 WEATHER RADAR CONTROLLER

OPERATION

The controls and display features of the WC- 884 Weather Radar Controller are indexed and identified in figure 3- 5. Brightness levels for all legend and controls on the indicator are controlled by the dimming bus for the aircraft panel.

Whenever single or dual radar controllers are used, the radar data is displayed on the EFIS, MFD, or NAV display.

AD- 46698- R2@

WC- 884 Weather Radar Controller

Figure 3- 5

1 BRT (Brightness)

The BRT switch is a rotary control that is used to set the radar (raster) brightness on the EFIS display.

2 TGT (Target Alert)

The TGT switch is an alternate- action, button that enables and disables the radar target alert feature. Target alert is selectable in all but the 300- mile range. When selected, target alert monitors beyond the selected range and 7.5_ on each side of the aircraft heading. If a return with certain characteristics is detected in the monitored area, the target alert changes from the green armed condition to the amber TGT warning condition. (Refer to the target alert characteristics in table 3- 5 for a target description.) The amber TGT alerts the pilot as to potentially hazardous targets directly in front and outside of the selected range. When the alert is given, the pilot should select longer ranges to view the questionable target. Target alert is inactive within the selected range.

PRIMUSr 880 Digital Weather Radar System

Selecting target alert forces the system into preset gain. Target alert can be selected in the WX and FP modes.

To activate target alert, the target must have the depth and range characteristics described in table 3- 5:

WC- 884 Controller Target Alert Characteristics

Table 3- 5

3 STB (Stabilization)

The STAB button is a that turns the pitch and roll stabilization ON and OFF.

This radar is normally attitude stabilized. It automatically compensates for roll and pitch maneuvers (refer to Section 5, Radar Facts, for a description of stabilization). The amber STB annunciator appears on the screen. It is also used with the STB adjust mode, and to override forced standby.

4 RCT (Rain Echo Attenuation Compensation Technique)

Selecting RCT forces the system to preset gain. When RCT is selected, the green REACT legend is displayed in the mode field. The RCT circuitry compensates for attenuation of the radar signal as it passes through rainfall. The cyan field indicates areas where further compensation is not possible. Any target detected within the cyan field cannot be calibrated and should be considered dangerous. All targets in the cyan field are displayed as fourth level precipitation, magenta.

NOTE: Refer to Section 5, Radar Facts, for a description of REACT.

PRIMUSr 880 Digital Weather Radar System

5 TRB (Turbulence Detection)

TRB switch is used to select the turbulence detection mode of operation. The TRB mode can only be selected if the MODE switch is in the WX position and the selected range is 50 miles or less. The weather/turbulence mode is annunciated in the mode field with the green WX/T legend. Areas of at least moderate turbulence are shown in soft white.

CAUTION

TURBULENCE CAN ONLY BE DETECTED WITHIN AREAS OF

RAINFALL. THE PRIMUSR 880 DIGITAL WEATHER RADAR

SYSTEM DOES NOT DETECT CLEAR AIR TURBULENCE.

WARNING

UNDETECTED TURBULENCE CAN EXIST WITHIN ANY STORM

CELL. REFER TO SECTION 5, RADAR FACTS, OF THIS GUIDE

FOR ADDITIONAL INFORMATION.

Selecting the 100--, 200--, or 300--mile range turns off the turbulence detection. The /T is deleted from the mode annunciation and variable gain is engaged if previously selected. Subsequent selection of ranges of 50 miles or less re--engages turbulence detection.

A description of the turbulence detection capabilities and limitations can be found in Section 5, Radar Facts, of this guide.

6 TILT

The TILT switch is a rotary control used to select tilt angle of antenna beam with relation to the horizon. CW rotation tilts beam upward to +15_; ccw rotation tilts beam downward to --15_.

A digital readout of the antenna tilt angle is displayed on the EFIS.

DPULL ACT (Altitude Compensated Tilt) Function -- When the TILT control knob is pulled out, the system engages the ACT (option). In ACT, the antenna tilt is automatically adjusted with regard to the selected range and barometric altitude. The antenna tilt automatically readjusts with changes in altitude and/or selected range. In ACT, the tilt control can fine tune the tilt setting by ??2??.

ACT is annunciated with an A following the digital tilt legend. The digital tilt readout always shows the commanded tilt of the antenna regardless of the tilt command source (ACT command or manual tilt command).

PRIMUSr 880 Digital Weather Radar System

WARNINGS

1.TO AVOID FLYING UNDER OR OVER STORMS,

FREQUENTLY SELECT MANUAL TILT TO SCAN BOTH

ABOVE AND BELOW YOUR FLIGHT LEVEL.

2.ALWAYS USE MANUAL TILT FOR WEATHER ANALYSIS.

7 RANGE

RANGE is a rotary control used to select one of six ranges (10, 25, 50, 100, 200, and 300 NM). The seventh position of the range switch is flight plan mode. Selecting FPLN blanks the radar information from the EFIS display and the mode annunciation flashes if a radiating mode is selected. The EFIS is set to a range determined by the installation.

Target alert can be used in the FPLN mode. With target alert on in the FPLN mode, the target alert armed annunciation (green TGT) is displayed. The RTA becomes active and starts searching for a hazardous target from 5 to 55 miles and ??7.5_ dead ahead. No radar targets are displayed. If a hazardous target is detected, the target alert armed annunciation switches to the alert annunciation (amber TGT). This advisory indicates that a hazardous target is in the aircraft???s flightpath and the WX mode should be selected.

8 SLV (Slave)

The SLV annunciator is a dead front annunciator that is only used in dual controller installations. With dual controllers, one controller can be slaved to the other by selecting the RADAR mode switch to OFF on that controller, only. This slaved condition is annunciated with the SLV annunciator.

In the slaved condition both controllers must be off before the radar system turns off.

9 MODE

The MODE switch is a rotary switch used to select one of the following functions:

D OFF - In this position the radar system is turned off.

D STBY - In this position the radar system is placed in standby; a ready state, with the antenna scan stopped, the transmitter inhibited, and the display memory erased. STBY, in green, is

displayed in the mode field.

If STBY is selected before the initial RTA warmup period is complete (approximately 45 - 90 seconds), the flashing WAIT legend is

displayed in the mode field.

PRIMUSr 880 Digital Weather Radar System

When the warmup is complete, the system changes the mode field from WAIT to STBY.

D TEST- This position selects the radar test mode. A test pattern is displayed to verify that system operates. The green TEST legend is displayed in the mode field. Refer to Section 4, Normal

Operation, for a description of the test pattern.

WARNING

UNLESS THE SYSTEM IS IN FORCED STANDBY, THE TRANSMIT-

TER IS ON AND RADIATING X- BAND MICROWAVE ENERGY IN

TEST MODE. REFER TO SECTION 6, MAXIMUM PERMISSI-

BLE EXPOSURE LEVEL (MPEL).

DWX - In this position, the radar system is fully operational and all internal parameters are set for enroute weather detection.

If WX is selected before the initial RTA warmup period is complete, a flashing WAIT legend is displayed. In WAIT mode, the transmitter and antenna scan are inhibited and the memory is erased. When the warmup is complete, the system automatically switches to the WX

mode and a green WX is displayed in mode field.

The system, in preset gain, is calibrated given in table NO TAG.

Rainfall Rate Color Coding

Table 3- 6

D GMAP - Selecting GMAP places the radar system in the ground mapping mode. The system is fully operational and all internal parameters are set to enhance returns from ground targets. RCT

compensation is inactive.

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.

PRIMUSr 880 Digital Weather Radar System

When GMAP is selected, a green GMAP legend is displayed and the color scheme is changed to cyan, yellow, magenta. Cyan represents the least reflective return, yellow is a moderate return,

and magenta is a strong return.

If GMAP is selected before the initial RTA warmup period is complete, a flashing WAIT legend is displayed. In WAIT mode, the transmitter and antenna scan are inhibited and the memory is erased. When the warmup is complete, the system automatically

switches to the GMAP mode.

WARNING

THE SYSTEM PERFORMS ONLY THE FUNCTIONS OF WEATHER

DETECTION OR GROUND MAPPING. IT CANNOT BE RELIED

UPON FOR PROXIMITY WARNING OR ANTICOLLISION

PROTECTION.

D FSBY - Forced standby is an automatic, nonselectable radar mode. As an installation option, the controllers can be wired to the WOW squat switch. When wired, the RTA is in the forced standby mode when the aircraft is on the ground. In the forced standby mode, the transmitter and antenna scan are both inhibited, the memory is erased, and the amber FSBY legend is displayed in the mode field. When in the forced standby mode, pushing the STAB

button 4 times in 3 seconds, exits the mode.

FSBY mode is a safety feature that inhibits the transmitter on the ground to eliminate the X- band microwave radiation hazard. Refer

to Section 6, Maximum Permissible Exposure Level (MPEL).

NOTE: In dual installations, overriding the forced standby using the TGT button is done on only one controller.

WARNING

FORCED STANDBY MODE MUST BE VERIFIED BY THE OPERATOR

TO ENSURE SAFETY FOR GROUND PERSONNEL.

10 GAIN

The GAIN is a single- turn rotary control and push/pull switch that is used to control the receiver gain. When the GAIN switch is pushed, the system enters the preset, calibrated gain mode. Calibrated gain is the normal mode and is used for weather avoidance. In calibrated gain, the rotary portion of the GAIN control does nothing.

PRIMUSr 880 Digital Weather Radar System

WARNING

WHEN LOW SETTINGS OF VARIABLE GAIN ARE USED,

HAZARDOUS TARGETS CAN BE ELIMINATED FROM

THE DISPLAY.

In the GMAP mode, variable gain is used to reduce the level of the typically very strong returns from ground targets.

Minimum gain is with the control at its full ccw position. Gain increases as the control is rotated in a cw direction from full ccw. At the full cw position, the gain is at maximum.

The VAR legend annunciates variable gain. Selecting RCT or TGT forces the system into preset gain. Preset gain is not annunciated.

HIDDEN MODES

The PRIMUS?? 880 has five hidden modes that are summarized as follows:

D Forced Standby (FSBY) Override

D Roll Offset

D Roll Gain (NOTE)

D Pitch Offset (NOTE)

D Pitch Gain (NOTE).

NOTE: At the time of installation, the programming strap STAB TRIM ENABLE, determines if the roll and pitch gain, and pitch offset adjustment features are available. Consult the aircraft installation information to determine the installed configuration.

Forced Standby Override

DFunction - Forced standby places the radar in a standby mode on the ground that prevents the radar from radiating and therefore, exposing ground personnel to radiation exposure. This mode is annunciated as FSBY (STBY on EFIS) in systems where mode annunciations are made.

DEntry Method - Power up aircraft on the ground or land the aircraft with the radar powered.

DExit Method - Push the STAB button 4 times within 3 seconds on radar indicator or on controller.

PRIMUSr 880 Digital Weather Radar System

Roll Offset

DFunction - Roll offset permits exact compensation of the antenna roll to eliminate the effects of small errors in the aircraft radar installation. Constantly lopsided ground returns can be eliminated. (Refer to Section 5, Radar Facts, table 5- 5.)

DEntry Method - Using only one controller that is in the WX and variable gain modes, select RCT OFF. Push STB 4 times within 3 seconds. Verify that VAR and RCT are not displayed.

D Control - The GAIN control is used to adjust the roll offset.

DExit Method - Push STAB (once) to continue with the next adjustment.

Roll Gain

DFunction - Roll gain corrects the installation at bank angles over 20??, for unsymmetrical radar displays.

DEntry Method - Selected by sequencing through the roll offset and pitch offset menus with the STAB button. (Refer to Section 5, Radar Facts, table 5- 9.)

D Control - Pull GAIN knob out and use it.

DExit Method - Push STAB (once) to continue with the next adjustment.

Pitch Offset

DFunction - Adjusts the pitch attitude of the antenna to allow radar returns, in straight and level flight, to conform to the radar range rings.

DEntry Method - Selected by sequencing through the roll offset menu with the STAB button. (Refer to Section 5, Radar Facts, table 5- 8.)

D Control - Pull the GAIN knob out and use it.

DExit Method - Push STAB (once) to continue with the next adjustment.

Pitch Gain

DFunction - Adjusts the gain if the radar display is in pitch so that the contour lines track the range lines at higher pitch attitudes.

PRIMUSr 880 Digital Weather Radar System

DEntry Method - Selected by sequencing through the roll offset, pitch offset, and roll gain menus with the STAB button. (Refer to Section 5, Radar Facts, table 5- 10.)

D Control - Pull the GAIN knob out and use it.

DExit Method - Push the GAIN knob in. Push STAB to exit and save settings.

NOTES: 1. If installation is configured only for roll offset adjustment, pushing the STB button saves and exits after the roll offset adjustment is made.

2.Upon exiting, stabilization may be either OFF or ON depending on how many times it was pushed during the procedure. Be sure to set stabilization OFF or ON as desired.

3.If upon entering the adjustment mode, no changes are desired, keep the gain knob pushed in and repeatedly push STAB until the mode is exited.

PRIMUSr 880 Digital Weather Radar System

WI--880 Indicator Test Pattern With TEXT FAULT Enabled

Figure 4--3

Standby

When Standby is selected, and the radar is not in dual control mode (refer to table 2--1, dual control mode truth table, for dual control operation), the antenna is stowed in a tilt--up position and is neither scanning nor transmitting.

Standby should be selected when the pilot wants to keep power applied to the radar without transmitting.

Radar Mode - Weather

For purposes of weather avoidance, pilots should familiarize themselves with FAA Advisory Circular AC 00--24B (1--20--83).Subject: ???Thunderstorms.??? The advisory circular is reproduced in Appendix A of this guide.

To help the pilot categorize storms as described in the advisory circular referenced above, the radar receiver gain is calibrated in the WX mode with the GAIN control in the preset position. The radar is not calibrated when variable gain is being used, but calibration is restored if RCT, TRB, or target alert (TGT) is selected.

PRIMUSr 880 Digital Weather Radar System

To aid in target interpretation, targets are displayed in various colors. Each color represents a specific target intensity. The intensity levels chosen are related to the National Weather Service (NWS) video integrated processor (VIP) levels.

In the WX mode, the system displays five levels as black, green, yellow, red, and magenta in increasing order of intensity.

If RCT is selected, the radar receiver adjusts the calibration automatically to compensate for attenuation losses as the radar pulse passes through weather targets on its way to illuminate other targets.

There is a maximum extent to which calibration can be adjusted. When this maximum value is reached, REACT compensation ceases. At this point, a cyan field is added to the display to indicate that no further compensation is possible.

In the absence of intervening targets, the range at which the cyan field starts is approximately 290?? with a 12--inch antenna. For the 18-- and 24--inch antennas, the cyan field starts beyond 300 NM and therefore will not be seen if there are no intervening targets.

The RCT feature includes attenuation compensation (Refer to Section 5, Radar Facts, of this guide for a description of attenuation compensation.). Rainfall causes attenuation and attenuation compensation modifies the color calibration to maintain calibration regardless of the amount of attenuation. Modifying the color calibration results in a change in the point where calibration can no longer keep the radar system calibrated for red level targets. The heavier the rainfall, the greater the attenuation and the shorter the range where XSTC runs out of control. Therefore, the range at which the cyan background starts varies depending on the amount of attenuation. The greater the attenuation, the closer the start of the cyan field.

The radar???s calibration includes a nominal allowance for radome losses. Excessive losses in the radome seriously affect radar calibration. One possible means of verification are signal returns from known targets. Honeywell recommends that the pilot report evidence of weak returns to ensure that radome performance is maintained at a level that does not affect radar calibration.

Target alert can be selected in any WX range. The target alert circuit monitors for hazardous targets within ???7.5_ of the aircraft centerline.

PRIMUSr 880 Digital Weather Radar System

Radar Mode - Ground Mapping

NOTE: Refer to Tilt Management in Section 5, Radar Facts, for additional information on the use of tilt control.

Ground- mapping operation is selected by setting the controls to GMAP. The TILT control is turned down until a usable amount of navigable terrain is displayed. The degree of down- tilt depends on the aircraft altitude and the selected range.

The receiver STC characteristics are altered to equalize ground- target reflection versus range. As a result, selecting preset GAIN generally creates the desired mapping display. However, the pilot can control the gain manually (by selecting manual gain and rotating the GAIN control) to help achieve an optimum display.

With experience, the pilot can interpret the color display patterns that indicate water regions, coast lines, hilly or mountainous regions, cities, or even large structures. A good learning method is to practice ground- mapping during flights in clear visibility where the radar display can be visually compared with the terrain.

TEST MODE

The PRIMUS?? 880 Digital Weather Radar System has a self- test mode and a maintenance function.

In the self- test (TST) mode a special test pattern is displayed as illustrated earlier in this section. The functions of this pattern are as follows:

DColor Bands - A series of green/yellow/red/magenta/white bands, indicate that the signal to color conversion circuits are operating normally.

The maintenance function lets the pilot or the line maintenance technician determine the major fault areas. The fault data can be displayed in one of two ways (selected at the time of installation):

DTEXT FAULT - A plain English text indicating the failure is placed in the test band.

DFault code - A fault code is displayed, refer to the maintenance manual for an explanation.

The indicator or EFIS display indicates a fault as noted below.

DDedicated Radar Indicator - A FAIL annunciation is shown at the top left corner of the test pattern. It indicates that the built- in test equipment (BITE) circuitry is detecting a malfunction. The exact nature of the malfunction can be seen by selecting TEST. (Refer to Section 7, In- Flight Troubleshooting.)

PRIMUSr 880 Digital Weather Radar System

5.Radar Facts

RADAR OPERATION

The PRIMUS?? 880 Digital Weather Radar works on an echo principle. The radar sends out short bursts of electromagnetic energy that travel through space as a radio wave. When the traveling wave of energy strikes a target, some of the energy reflects back to the radar receiver. Electronic circuits measure the elapsed time between the transmission and the reception of the echo to determine the distance to the target (range). Because the antenna beam is scanning right and left in synchronism with the sectoring sweep on the indicator, the bearing of the target is found, as shown in figure 5- 1.

The indicator with the radar is called a plan- position indicator (PPI) type. When an architect makes a drawing for a house, one of the views he generally shows is a plan view, a diagram of the house as viewed from above. The PPI aboard an airplane presents a cross sectional picture of the storm as though viewed from above. In short, it is NOT a horizon view of the storm cells ahead but rather a MAP view. This positional relationship of the airplane and the storm cells, as displayed by the indicator, is shown in figure 5- 1.

PRIMUSr 880 Digital Weather Radar System

AIRCRAFT HEADING

Positional Relationship of an Airplane and

Storm Cells Ahead as Displayed on Indicator

Figure 5- 1

The drawing is laid out to simulate the face of the indicator with the semicircular range marks. To derive a clearer concept of the picture that the indicator presents, imagine that the storm is a loaf of sliced bread standing on end. From a point close to the surface of earth, it towers to a high- altitude summit. Without upsetting the loaf of bread, the radar removes a single slice from the middle of the loaf, and places this slice flat upon the table. Looking at the slice of bread from directly above, a cross section of the loaf can be seen in its broadest dimension. In the same manner, the radar beam literally slices out a horizontal cross section of the storm and displays it as though the viewer was looking

PRIMUSr 880 Digital Weather Radar System

at it from above, as shown in figure 5- 2. The height of the slice selected for display depends upon the altitude and also upon the upward or downward TILT adjustment made to the antenna.

Antenna Beam Slicing Out Cross Section of Storm

During Horizontal Scan

Figure 5- 2

Weather radar can occasionally detect other aircraft, but it is not designed for this purpose and should never be considered a collision- avoidance device. Nor is weather radar specifically designed as a navigational aid, but it can be used for ground mapping by tilting the antenna downward. Selecting the GMAP mode enhances returns from ground targets.

PRIMUSr 880 Digital Weather Radar System

When the antenna is tilted downward for ground mapping, two phenomena may occur that can confuse the pilot. The first is called ???The Great Plains Quadrant Effect???that is seen most often when flying over the great plains of central United States. In this region, property lines (fences), roads, houses, barns, and power lines tend to be laid out in a stringent north- south/east- west orientation. As a result, radar returns from these cardinal points of the compass tend to be more intense than returns from other directions and the display shows these returns as bright north/south/east/west spokes overlaying the ground map.

The second phenomenon is associated with radar returns from water surfaces (generally called sea clutter), as shown in figure 5- 3. Calm water reflects very low radar returns since it directs the radar pulses onward instead of backward (i.e. the angle of incidence from mirrored light shone on it at an angle). The same is true when viewing choppy water from the upwind side. The downwind side of waves, however, can reflect a strong signal because of the steeper wave slope. A relatively bright patch of sea return, therefore, indicates the direction of surface winds.

REFLECTION

PATCH

OF SEA

RETURNS

AD- 12056- R2@

Sea Returns

Figure 5- 3

PRIMUSr 880 Digital Weather Radar System

TILT MANAGEMENT

The pilot can use tilt management techniques to minimize ground clutter when viewing weather targets.

Assume the aircraft is flying over relatively smooth terrain which is equivalent to sea level in altitude. The pilot must make adjustments for the effects of mountainous terrain.

The figures below help to visualize the relationship between tilt angle, flight altitude, and selected range. Figures 5- 4 and 5- 5 show the distance above and below aircraft altitude that is illuminated by the flat- plate radiator during level flight with 0_ tilt. Figures 5- 6 and 5- 7 show a representative low altitude situation, with the antenna adjusted for 2.8_ up- tilt.

ELEVATION IN FEET

Radar Beam Illumination High Altitude

12- Inch Radiator

Figure 5- 4

ELEVATION IN FEET

Radar Beam Illumination High Altitude

18- Inch Radiator

Figure 5- 5

PRIMUSr 880 Digital Weather Radar System

Tables 5- 1 and 5- 2 give the approximate tilt settings at which ground targets begin to be displayed on the image periphery for 12- and 18- inch radiators. The range at which ground targets can be observed is affected by the curvature of the earth, the distance from the aircraft to the horizon, and altitude above the ground. As the tilt control is rotated downward, ground targets first appear on the display at less than maximum range.

NOTE: Operation with a 24- inch radiator is similar.

To find the ideal tilt angle after the aircraft is airborne, adjust the TILT control so that groundclutter does not interfere with viewing of weather targets. Usually, this can be done by tilting the antenna downward in 1_ increments until ground targets begin to appear at the display periphery. Ground returns can be distinguished from strong storm cells by watching for closer ground targets with each small downward increment of tilt. The more the downward tilt, the closer the ground targets that are displayed.

When ground targets are displayed, move the tilt angle upward in 1_ increments until the ground targets begin to disappear. Proper tilt adjustment is a pilot judgment, but typically the best tilt angle lies where ground targets are barely visible or just off the radar image.

Tables 5- 1 and 5- 2 give the approximate tilt settings required for different altitudes and ranges. If the altitude changes or a different range is selected, adjust the tilt control as required to minimize ground returns.

PRIMUSr 880 Digital Weather Radar System

LINE OF

SIGHT (NM)

246

230

213

195

174

151

123

AD- 29830- R2@

Approximate Tilt Setting for Minimal Ground Target Display 12- Inch Radiator

Table 5- 1

Tilt angles shown are approximate. Where the tilt angle is not listed, the operator must exercise good judgment.

NOTE: The line of sight distance is nominal. Atmospheric conditions and terrain offset this value.

PRIMUSr 880 Digital Weather Radar System

200

- 2

(LINE OF SIGHT LIMITED REGION)

Line of

Sight

(NM)

246

230

213

195

174

151

123

AD- 50232@

Approximate Tilt Setting for Minimal Ground Target Display 24- Inch Radiator

Table 5- 3

Tilt angles shown are approximate. Where the tilt angle is not listed, the operator must exercise good judgement.

NOTE: The line of sight distance is nominal. Atmospheric conditions and terrain offset this value.

PRIMUSr 880 Digital Weather Radar System

Tilt management is often misunderstood. It is crucial to safe operation of airborne weather radar. If radar tilt angles are not properly managed, weather targets can be missed or underestimated.

The upper levels of convective storms are the most dangerous because of the probability of violent windshears and large hail. But hail and winshear are not very reflective because they lack reflective liquid water.

The figures that follow show the relationship between flight situations and the correct tilt angle. The first describes a high altitude situation; the second describes a low altitude situation.

DThe ideal tilt angle shows a few ground targets at the edge of the display (see figure 5- 8).

GROUND

RETURN

AD- 35694@

Ideal Tilt Angle

Figure 5- 8

DEarth???s curvature can be a factor if altitude is low enough, or if the selected range is long enough, as shown in figure 5- 9.

GROUND

RETURN

AD- 35695@

Earth???s Curvature

Figure 5- 9

PRIMUSr 880 Digital Weather Radar System

DConvective thunderstorms become much less reflective above the freezing level. This reflectivity decreases gradually over the first 5000 to 10,000 feet above the freezing level, as shown in figure 5- 10.

FREEZING LEVEL

AD- 35696@

Convective Thunderstorms

Figure 5- 10

The aircraft in figure 5- 10 has a clear radar indication of the thunderstorm, probably with a shadow in the ground returns behind it.

DIf the tilt angle shown in figure 5- 11 is not altered, the thunderstorm appears to weaken as the aircraft approaches it.

FREEZING LEVEL

AD- 35697@

Unaltered Tilt

Figure 5- 11

PRIMUSr 880 Digital Weather Radar System

DProper tilt management demands that tilt be changed continually when approaching hazardous weather so that ground targets are not painted by the radar beam, as shown in figure 5- 12.

FREEZING

LEVEL

AD- 35698@

Proper Tilt Technique

Figure 5- 12

DAfter heading changes in a foul weather situation, the pilot should adjust the tilt to see what was brought into the aircraft???s flightpath by the heading changes, as shown in figure 5- 13.

DISPLAY BEFORE

TURN

DISPLAY AFTER

TURN

THUNDERSTORM WAS OUT

OF DISPLAY BEFORE TURN

AND IS NOW UNDER BEAM

AD- 30429@

Tilt Management With Heading Changes

Figure 5- 13

PRIMUSr 880 Digital Weather Radar System

DUnder the right conditions, a dangerous thunder bumper can develop in 10 minutes, and can in fact spawn and mature under the radar beam as the aircraft approaches it, as shown in figure 5- 14.

If flying at 400 kt groundspeed, a fast developing thunderstorm that spawns 67 NM in front of the aircraft can be large enough to damage the aircraft by the time it arrives at the storm.

THUNDERSTORM MATURES

AS IT APPROACHES

FREEZING

LEVEL

AD- 35699@

Fast Developing Thunderstorm

Figure 5- 14

DAt low altitude, the tilt should be set as low as possible to get ground returns at the periphery only as shown in figure 5- 15.

CORRECT WRONG

FREEZING

LEVEL

AD- 35700@

Low Altitude Tilt Management

Figure 5- 15

Excess up- tilt should be avoided as it can illuminate weather above the freezing level.

NOTE: The pilot should have freeze level information as a part of the flight planning process.

PRIMUSr 880 Digital Weather Radar System

DThe antenna size used on the aircraft alters the best tilt settings by about 1_. However, tilt management is the same for either size, as shown in figure 5- 16.

10- IN. ANTENNA

HAS 10 BEAM 12- IN. ANTENNA HAS 7.9 BEAM

18- IN. ANTENNA HAS 5.6 BEAM

24- IN. ANTENNA HAS 4.2 BEAM

Antenna Size and Impact on Tilt Management

Figure 5- 16

NOTE: A 10- inch antenna is shown for illustration purposes only.

DSome of the rules of thumb are described below and shown in figure 5- 17.

-A 1_ look down angle looks down 100 ft per mile

-Bottom of beam is 1/2 beam width below tilt setting

-A 12- inch antenna grazes the ground at 100 NM if set to 0_ tilt at 40,000 ft.

TILT

BEAM WIDTH

AD- 35702@

Rules of Thumb

Figure 5- 17

PRIMUSr 880 Digital Weather Radar System

ALTITUDE COMPENSATED TILT (ACT)

The PRIMUS?? 880 Digital Weather Radar has an ACT feature that can be selected by pulling out the tilt control knob. This feature is annunciated on the radar display by adding an A suffix to the tilt readout. While in ACT or manual tilt the digital tilt readout always shows the actual (true) tilt of the antenna.

In ACT, the antenna tilt is automatically adjusted with regard to the selected range and the aircraft???s barometric attitude. ACT adjusts the tilt to show a few ground targets at the edge of the display. In ACT, the ideal setting can be adjusted ?? 2??to accommodate terrain height or pilot preferences.

NOTE: Since ACT uses air data computer barometric altitude to adjust the tilt, operating near high altitude airports or even high terrain can result in a lower than desired tilt angle. In such cases, use of the manual tilt is recommended.

To calculate the tilt angle, the weather radar uses the air data computer???s barometric altitude with reference to an assumed ground level of 2000 feet above sea level. This assumed ground level is a factor during low altitude flight, especially when flying in mountainous areas. The ground targets that are usually at the edge of the display tend to migrate to the middle of the display. This also happens when longer ranges (200 NM to 300 NM) are selected and the altitude is such that the earth???s curvature is a factor.

In ACT the range control can be used to sweep the beam along the ground to look for storms at various ranges, as shown in figure 5- 18.

ACT is best suited for high altitude operation while in the weather surveillance mode; i.e., aircraft is in cruise and there is no weather within 100 NM. The operator can then use the range control to frequently sweep the beam down to avoid overflying any fast developing storms.

At lower altitudes, manual tilt should be used to frequently sweep above and below the flight level to avoid flying under or over storms, as shown in figure 5- 18. Manual tilt should also be used exclusively when analyzing weather.

NOTE: The radar system does not have enough information to be able to tilt the beam into the wet, lower portions of cells by itself. The operator must manage tilt dynamically or manually to locate and analyze weather. ACT simply adjusts the beam to the earth???s surface at the selected maximum range. Also, it assumes that the surface is at 2000 feet above sea level.

PRIMUSr 880 Digital Weather Radar System

STABILIZATION

The purpose of the stabilization system is to hold the elevation of the antenna beam relative to the earth???s surface constant at all azimuths, regardless of aircraft bank and pitch maneuvers. The stabilization system uses the aircraft attitude source as a reference.

Several sources of error exist in any stabilization system.

Dynamic Error

Dynamic error is the basis of the stabilization system. Stabilization is a corrective process. It logically follows that there must first be some error to correct. In stabilization, this error is called dynamic. An example of dynamic error occurs when a gust lifts the right wing and the pilot instinctively raises the right aileron and lowers the left. In this action, the pilot detects a changing (dynamic) error in aircraft attitude and corrects it.

As the gust lifts the wing, the aircraft attitude source sends a continuous stream of attitude change information to stabilization circuits which, in turn, control the motors that raise and lower the beam. In short, a dynamic error in aircraft attitude (as seen by the radar) is detected, and the antenna attitude is corrected for it. Extremely small errors of less than 1_ can be detected and compensated. However, the point is ultimately reached where dynamic error is too small to be detected. Without detection, there is no compensation.

Accelerative Error

One of the most common forms of error seen in a radar- antenna stabilization system results from forces of acceleration on the aircraft equipped with a vertical gyroscope. Acceleration forces result from speeding up, slowing down, or turning. Radar stabilization accuracy depends upon the aircraft vertical gyroscope. Therefore, any gyroscopic errors accumulated through acceleration are automatically imparted to the antenna stabilization system.

A vertical gyroscope contains a gravity- sensitive element, a heavily dampened pendulous device that enables the gyro to erect itself to earth gravity at the rate of approximately 2_/min. The pendulous device is unable to differentiate between earth gravity and an acceleration force. It tends to rest at a false- gravity position where the forces of gravity and acceleration are equal. As long as the acceleration force persists, the gyroscope precesses toward a false- gravity position at the rate of approximately 2_/min. The radar follows the gyroscope into error at the same rate. When the acceleration force ceases, the gyroscope precesses back to true gravity erection at the same rate.

PRIMUSr 880 Digital Weather Radar System

Some vertical gyroscopes have provisions for deactivating the roll- erection torque motor (whenever the airplane banks more than approximately 6_) to reduce the effect of lateral acceleration during turns. To some extent, stabilization error is displayed in the radar image after any speed change and/or turn condition. If the stabilization system seems to be in error because the radar begins ground mapping on one side and not the other, or because it appears that the tilt adjustment has slipped, verify that aircraft has been in nonturning, constant- speed flight long enough to allow the gyroscope to erect on true earth gravity.

When dynamic and acceleration errors are taken into account, maintaining accuracy of 1/2 of 1_ or less is not always possible. Adjust the antenna tilt by visually observing the ground return. Then, slowly tilt the antenna upward until terrain clutter no longer enters the display, except at the extreme edges. If ground display is observed on one side but not on the other, the stabilization system is somewhat in error, but it is probably impossible to adjust it more accurately.

Pitch and Roll Trim Adjustments

The PRIMUS?? 880 is delivered from the Honeywell factory or repair facility adjusted for correct pitch and roll stabilization and should be ready for use. However, due to the tolerances of some vertical reference sources, you may elect to make a final adjustment whenever the radar or vertical reference is replaced on the aircraft, or if stabilization problems are observed in flight.

The four trim adjustments and their effects are summarized in table 5- 4.

PRIMUSr 880 Digital Weather Radar System

Generally, it is recommended to perform trim adjustments only if noticeable effects are being observed.

Pitch and Roll Trim Adjustments Criteria

Table 5- 4

NOTES: 1. Depending on the installation, not all of the adjustments shown in table 5- 4 are available. If STAB TRIM ENABLE programming strap is open, only the roll offset adjustment is available. If STAB TRIM ENABLE is grounded, all four adjustments are available. Consult the installation configuration information for details.

2.After any adjustment procedure is completed, monitor the ground returns displayed by the radar during several pitch and roll maneuvers. Verify that the ground returns stay somewhat constant during changes in aircraft orientations. If not, repeat the adjustment procedure.

3.After the trim adjustment feature is selected, more than one adjustment can be made. They are available in the sequence shown in table 5- 4, and can be done in the sequence of first finishing one adjustment, then proceeding to do the next by pushing the STAB button.

PRIMUSr 880 Digital Weather Radar System

GMAP

AD- 17720- R1@

Symmetrical Ground Returns

Figure 5- 19

GMAP

AD- 17721- R1@

Ground Return Indicating Misalignment (Upper Right)

Figure 5- 20

PRIMUSr 880 Digital Weather Radar System

GMAP

AD- 17722- R1@

Ground Return Indicating Misalignment (Upper Left)

Figure 5- 21

ROLL STABILIZATION CHECK

Once proper operation is established in level flight, verify stabilization in a turn using the procedure in table 5- 6.

1Place the aircraft in 20??roll to the right.

2Note the radar display. It should contain appreciably no more returns than found during level flight. Figure 5- 22 indicates that roll stabilization is inoperative.

3If returns display on the right side of radar indicator; the radar system is understabilizing.

4Targets on the left side of the radar display indicate the system is Overstabilizing. Refer to table 5- 9 for roll gain adjustment.

NOTE: Proper radar operation in turns depends on the accuracy and stability of the installed attitude source.

Stabilization in Turns Check Procedure

Table 5- 6

PRIMUSr 880 Digital Weather Radar System

In prolonged turns, gyro precession can occur that is tracked by the stabilization system and appears as undesirable ground targets on the indicator. For example, a 1??precession error (which would probably not be noticed on the gyro horizon) moves the antenna beam approximately 10,500 feet at a point 100 NM from the aircraft, If ground targets between 50 and 80 NM depending on aircraft altitude and the actual setting of the tilt control.

GMAP

AD- 17723- R1@

Roll Stabilization Inoperative

Figure 5- 22

PRIMUSr 880 Digital Weather Radar System

INTERPRETING WEATHER RADAR IMAGES

From a weather standpoint, hail and turbulence are the principal obstacles to a safe and comfortable flight. Neither of these conditions is directly visible on radar. The radar shows only the rainfall patterns with which these conditions are associated.

The weather radar can see water best in its liquid form, as shown in figure 5- 25 (not water vapor; not ice crystals; not hail when small and perfectly dry). It can see rain, wet snow, wet hail, and dry hail when its diameter is about 8/10 of the radar wavelength or larger. (At X- band, this means that dry hail becomes visible to the radar at about 1- in. diameter.)

ICE CRYSTALS

DRY HAIL - POOR

DRY SNOW - VERY POOR

SMALL DRY HAIL

AD- 46704- R1@

Weather Radar Images

Figure 5- 25

PRIMUSr 880 Digital Weather Radar System

The following are some truths about weather and flying, as shown in figure 5- 26.

DTurbulence results when two air masses at different temperatures and/or pressures meet.

D This meeting can form a thunderstorm.

D The thunderstorm produces rain.

D The radar displays rain (thus revealing the turbulence).

DIn the thunderstorm???s cumulus stage, echoes appear on the display and grow progressively larger and sharper. The antenna can be tilted up and down in small increments to maximize the echo pattern.

DIn the thunderstorm???s mature stage, radar echoes are sharp and clear; hail occurs most frequently early in this stage.

DIn the thunderstorm???s dissipating stage, the rain area is largest and shows best with a slight downward antenna tilt.

Radar can be used to look inside the precipitation area to spot zones of present and developing turbulence. Some knowledge of meteorology is required to identify these areas as being turbulent. The most important fact is that the areas of maximum turbulence occur where the most abrupt changes from light or no rain to heavy rain occur. The term applied to this change in rate is rain gradient. The greater the change in rainfall rate, the steeper the rain gradient. The steeper the rain gradient, the greater the accompanying turbulence. More important, however, is another fact: Storm cells are not static or stable, but are in a constant state of change. While a single thunderstorm seldom lasts more than an hour, a squall line, shown in figure 5- 27 can contain many such storm cells developing and decaying over a much longer period. A single cell can start as a cumulus cloud only 1 mile in diameter, rise to 15,000 ft, grow within 10 minutes to 5 miles in diameter and tower to an altitude of 60,000 feet or more. Therefore, weather radar should not be used to take flash pictures of weather, but to keep weather under continuous surveillance.

PRIMUSr 880 Digital Weather Radar System

Radar and Visual Cloud Mass

Figure 5- 26

As masses of warm, moist air are hurled upward to meet the colder air above, the moisture condenses and builds into raindrops heavy enough to fall downward through the updraft. When this precipitation is heavy enough, it can reverse the updraft. Between these downdrafts (shafts of rain), updrafts continue at tremendous velocities. It is not surprising, therefore, that the areas of maximum turbulence are near these interfaces between updraft and downdraft. Keep these facts in mind when tempted to crowd a rain shaft or to fly over an innocent- looking cumulus cloud.

PRIMUSr 880 Digital Weather Radar System

To find a safe and comfortable route through the precipitation area, study the radar image of the squall line while closing in on the thunderstorm area. In the example shown in figure 5- 27, radar observation shows that the rainfall is steadily diminishing on the left while it is very heavy in two mature cells (and increasing rapidly in a third cell) to the right. The safest and most comfortable course lies to the left where the storm is decaying into a light rain. The growing cell on the right should be given a wide berth.

OUTLINE OF RAIN AREA VISIBLE TO RADAR

Squall Line

Figure 5- 27

PRIMUSr 880 Digital Weather Radar System

WEATHER DISPLAY CALIBRATION

Ground based radar observers of the National Weather Service (NWS) currently use video integrator processor (VIP) levels in reporting thunderstorm intensity levels. These radar echo intensity levels are on a scale of one to six. Refer to Section 6 of FAA Advisory Circular AC- 00- 24B for additional details.

To assist the pilot in categorizing storms in accordance with VIP levels, the indicator display colors represent calibrated rainfall rates in WX and preset calibrated gain. The relationship between the 4- color calibrations and the VIP levels is shown in table 5- 11.

As covered in the RCT description, intervening attenuating rainfall reduces the calibrated range and the radar can incorrectly depict the true cell intensity.

The radar calibration includes a nominal allowance for radome losses. Excessive losses in the radome seriously affect radar calibration. One possible means of verification is signal returns from known ground targets. It is recommended that you report evidence of weak returns to ensure that radome performance is maintained at a level that does not affect radar calibration.

To test for a performance loss, note the distance at which the aircraft???s base city, a mountain, or a shoreline can be painted from a given altitude. When flying in familiar surroundings, verify that landmarks can still be painted at the same distances.

Any loss in performance results in the system not painting the reference target at the normal range.

PRIMUSr 880 Digital Weather Radar System

*THE THRESHOLD FOR THE VIP LEVELS CAN BE REALIZED WHEN THERE IS NO INTERVENING RADAR

SIGNAL ATTENUATION. WITH RCT SELECTED, RCT BLUE FIELD OCCURS WHEN THE MINIMUM RED

LEVEL DETECTED IS BELOW SYSTEM SENSITIVITY.

AD- 17926- R5@

Display Levels Related to VIP Levels (Typical)

Table 5- 11

NOTE: The radar is calibrated for convective weather. Stratiform storms at or near the freezing level can show high reflectivity. Do not penetrate such targets.

PRIMUSr 880 Digital Weather Radar System

VARIABLE GAIN CONTROL

The PRIMUS?? 880 Digital Weather Radar variable gain control is a single turn rotary control and a push/pull switch that is used to control the radar???s receiver gain. With the switch pushed in, the system is in the preset, calibrated gain mode. In calibrated gain, the rotary control does nothing.

When the GAIN switch is pulled out, the system enters the variable gain mode. Variable gain is useful for additional weather analysis. In the WX mode, variable gain can increase receiver sensitivity over the calibrated level to show very weak targets or it can be reduced below the calibrated level to eliminate weak returns.

WARNING

LOW VARIABLE GAIN SETTINGS CAN ELIMINATE HAZARDOUS

TARGETS.

RAIN ECHO ATTENUATION COMPENSATION

TECHNIQUE (REACT)

Honeywell???s REACT feature has three separate, but related functions.

DAttenuation Compensation - As the radar energy travels through rainfall, the raindrops reflect a portion of the energy back toward the airplane. This results in less energy being available to detect raindrops at greater ranges. This process continues throughout the depth of the storm, resulting in a phenomenon known as attenuation. The amount of attenuation increases with an increase in rainfall rate and with an increase in the range traveled through the rainfall (i.e., heavy rain over a large area results in high levels of attenuation, while light rain over a small area results in low levels of attenuation).

Storms with high rainfall rates can totally attenuate the radar energy making it impossible to see a second cell hidden behind the first cell. In some cases, attenuation can be so extreme that the total depth of a single cell cannot be shown.

Without some form of compensation, attenuation causes a single cell to appear to weaken as the depth of the cell increases.

PRIMUSr 880 Digital Weather Radar System

Honeywell has incorporated attenuation compensation that adjusts the receiver gain by an amount equal to the amount of attenuation. That is, the greater the amount of attenuation, the higher the receiver gain and thus, the more sensitive the receiver. Attenuation compensation continuously calibrates the display of weather targets, regardless of the amount of attenuation.

With attenuation compensation, weather target calibration is maintained throughout the entire range of a single cell. The cell behind a cell remains properly calibrated, making proper calibration of weather targets at long ranges possible.

DCyan REACT Field - From the description of attenuation, it can be seen that high levels of attenuation (caused by cells with heavy rainfall) causes the attenuation compensation circuitry to increase the receiver gain at a fast rate.

Low levels of attenuation (caused by cells with low rainfall rates) cause the receiver gain to increase at a slower rate.

The receiver gain is adjusted to maintain target calibration. Since there is a maximum limit to receiver gain, strong targets (high attenuation levels) cause the receiver to reach its maximum gain value in a short time/short range. Weak or no targets (low attenuation levels) cause the receiver to reach its maximum gain value in a longer time/longer range. Once the receiver reaches its maximum gain value, weather targets can no longer be calibrated. The point where red level weather target calibration is no longer possible is highlighted by changing the background field from black to cyan.

Any area of cyan background is an area where attenuation has caused the receiver gain to reach its maximum value, so further calibration of returns is not possible. Extreme caution is recommended in any attempt to analyze weather in these cyan areas. The radar cannot display an accurate picture of what is in these cyan areas. Cyan areas should be avoided.

NOTE: If the radar is operated such that ground targets are affecting REACT, they could cause REACT to provide invalid indications.

Any target detected inside a cyan area is automatically forced to a magenta color indicating maximum severity. Figure 5- 28 shows the same storm with REACT OFF and with REACT ON.

PRIMUSr 880 Digital Weather Radar System

Shadowing

An operating technique similar to the REACT blue field is shadowing. To use the shadowing technique, tilt the antenna down until ground is being painted just in front of the storm cell(s). An area of no ground returns behind the storm cell has the appearance of a shadow behind the cell. This shadow area indicates that the storm cell has totally attenuated the radar energy and the radar cannot show any additional targets (WX or ground) behind the cell. The cell that produces a radar shadow is a very strong and dangerous cell. It should be avoided by 20 miles.

WARNING

DO NOT FLY INTO THE SHADOW BEHIND THE CELL.

Turbulence Probability

The graph of turbulence probability is shown in figure 5- 29. This graph shows the following:

DThere is a 100% probability of light turbulence occurring in any area of rain.

DA level one storm (all green) has virtually no chance of containing severe or extreme turbulence but has between a 5% and 20% chance that moderate turbulence exists.

DA level two storm (one containing green and yellow returns) has virtually no probability of extreme turbulence but has a 20% to 40% chance of moderate turbulence and up to a 5% chance of severe turbulence.

DA level three storm (green, yellow, and red radar returns) has a 40% to 85% chance of moderate turbulence, a 5% to 10% chance of severe turbulence, and a slight chance of extreme turbulence.

DA level four storm (one with a magenta return) has moderate turbulence, a 10% to 50% chance of severe turbulence, and a slight to 25% chance of extreme turbulence.

WARNING

THE AREAS OF TURBULENCE MAY NOT BE ASSOCIATED WITH

THE MAXIMUM RAINFALL AREAS. THE PROBABILITIES OF

TURBULENCE ARE STATED FOR THE ENTIRE STORM AREA,

NOT JUST THE HEAVY RAINFALL AREAS.

PRIMUSr 880 Digital Weather Radar System

Although penetrating a storm with a red (level three) core appears to be an acceptable risk, it is not. At the lower end of the red zone, there is no chance of extreme turbulence, a slight chance of severe turbulence, and a 40% chance of moderate turbulence. However, the radar lumps all of the rainfall rates between 12 mm to 50 mm per hour into one group - a level three (red). Once the rainfall rate reaches the red threshold, it masks any additional information about the rainfall rate until the magenta threshold is reached. A red return covers a range of turbulence probabilities and the worst case must be assumed, especially since extreme, destructive turbulence is born in the red zone. Therefore, once the red threshold is reached, the risk in penetration becomes totally unacceptable.

Likewise, once the magenta threshold is reached, it must be assumed that more severe weather is being masked.

Probability of Turbulence Presence

in a Weather Target

Figure 5- 29

PRIMUSr 880 Digital Weather Radar System

Turbulence Detection Theory

The PRIMUS?? 880 Digital Weather Radar uses a turbulence detection technique called Pulse Pair Processing (PPP). The PPP technique used in the new PRIMUS?? 880 Digital Weather Radar is adapted from the proven technique used in the earlier PRIMUS?? Weather Radars.

In the turbulence detection mode of operation, the PRIMUS?? 880 Digital Weather Radar transmits about 1400 pulses per second with a power of 10 kW. The pulse pair processor compares the returns from successive pulses to determine the presence of turbulence (i.e., the return from pulse one is compared to the return from pulse two, pulse two???s return is compared to pulse three???s, and so on). Since the processor is comparing the returns from two subsequent pulses (a pair), it was given the name pulse pair processor.

To perform the comparison, the radar first divides the selected range into 128 equal parts with each part called a range bin. The radar compares the return data in each range bin for the first pulse with the return data in each range bin for the second pulse. For example, the data returned from pulse one in range bin 34 is compared to the data returned from pulse two in range bin 34. This process continues throughout the entire area covered by the radar (all range bins) and a turbulence decision is made for each range bin. When turbulence is detected in any bin, the color of that bin is made white.

The return data being compared is the total return vector (TRV). TRV is the vector sum of the return from each raindrop contained within the range bin. In other words, the first pulse TRV of range bin 34 is compared to the TRV for pulse two in range bin 34. A total return vector is shown in figure 5- 30.

In the simplified example of figure 5- 30, the range bin contains five raindrops of equal size that are at slightly different ranges. The amplitudes of the returns from the raindrops (vector length) are identical because all the drops are equal in size, but the phase (vector rotation) of the individual returns varies because of the variation in the range of the raindrops. The radar does not see the individual returns, rather it sees the total return vector which is the vector sum of the returns from all the individual raindrops. In reality, the range bin could contain thousands and thousands of raindrops which means that a longer chain of vectors are summed, but the result is still one total return vector.

PRIMUSr 880 Digital Weather Radar System

With the very short time between radar pulses when in the turbulence mode (one pulse every .0008 second), little or no turbulence results in little or no change in the size or position of the raindrops. This results in little or no change in the individual returns from each raindrop and a commensurate little or no change in the total return vector. Therefore, when there is little or no difference between two subsequent total return vectors in the same range bin, there is little or no turbulence in that range bin. This is illustrated by comparing figures 5- 30 and 5- 31.

If turbulence is present in the precipitation, there is a significant change in the raindrop size and/or position between the subsequent radar pulses. This difference results in a change in the individual return vectors from each raindrop and a commensurate change in the total return vector. Therefore, if there is a significant difference between pairs of total return vectors for the same range bin, that bin contains turbulence and is displayed in white. This is illustrated by comparing figures 5- 30 and 5- 32.

The presence of turbulence is detected by comparing the amplitude of subsequent total return vectors.

To measure raindrop motion, the turbulence detection circuitry measures the raindrop motion directly toward and away from the antenna. Raindrop motion that is perpendicular to the antenna does not produce any doppler effect and cannot be measured by the turbulence detection circuitry. For this reason, there can be areas of turbulence not detectable by radar, or the displayed areas of turbulence can change from antenna scan to antenna scan as the turbulence throws the raindrops in various directions.

WARNING

AREAS OF TURBULENCE CAN NOT ALWAYS BE

DETECTED BY THE RADAR.

PRIMUSr 880 Digital Weather Radar System

TURBULENT

AD- 17727- R1@

Turbulent

Figure 5- 32

Turbulence Detection Operation

With the radar in the WX mode and with 50 miles or less range selected, pushing the TRB switch turns on the turbulence detection mode. Areas of detected turbulence are displayed in soft white, as shown in figure 5- 33. Soft white is a high contrast shade of white that has a slight gray appearance.

Weather Display With Turbulence

Figure 5- 33

If any range greater than 50 miles is selected, turbulence detection turns off and remains off until 50 miles or less is reselected. Similarly, if any mode other than WX is selected, turbulence detection turns off.

PRIMUSr 880 Digital Weather Radar System

Mode annunciation for the turbulence detection mode is the /T legend that is added to the WX annunciation. The resultant annunciation is WX/T for weather and turbulence. The color bar legend on the dedicated radar indicator includes a T within a soft white square whenever turbulence detection is turned on. EFIS/MFD does not have a color bar legend.

The PRIMUS?? 880 Digital Weather Radar measures the motion of raindrops to determine areas of turbulence. The radar must detect precipitation before it can detect turbulence. It cannot detect clear air turbulence.

WARNING

THE PRIMUS?? 880 DIGITAL WEATHER RADAR CAN ONLY DETECT

TURBULENCE WITHIN AREAS OF PRECIPITATION. IT CANNOT DE-

TECT CLEAR AIR TURBULENCE.

The turbulence detection threshold is moderate turbulence. That is, any area of raindrop motion that is detected as moderate, severe, or extreme turbulence is displayed in white. Areas shown as turbulent are at least moderate turbulence and can be severe, extreme, or combinations of the three levels of turbulence. All three must be avoided.

Turbulence is most accurately measured within ? 30_ of straight ahead. Turbulence measurements outside this area experience reduced accuracy. The reduced accuracy results from the effects of the antenna scan angle and aircraft motion. Levels of turbulence are described in the Airman???s Information Manual and are shown in figure 5- 34.

PRIMUSr 880 Digital Weather Radar System

Turbulence Levels

(From Airman???s Information Manual)

Figure 5- 34

Hail Size Probability

Whenever the radar shows a red or magenta target, the entire storm cell should be considered extremely hazardous and must not be penetrated. Further support for this statement comes from the hail probability graph shown in figure 5- 35. The probability of destructive hail starts at a rainfall rate just above the red level three threshold.

Like precipitation, the red and magenta returns should be considered as a mask over more severe hail probabilities.

By now, it should be clear that the only safe way to operate in areas of thunderstorm activity is to AVOID ALL CELLS THAT HAVE RED OR

MAGENTA RETURNS.

PRIMUSr 880 Digital Weather Radar System

Hail Size Probability

Figure 5- 35

Spotting Hail

As previously stated, dry hail is a poor reflector, and therefore generates deceptively weak or absent radar returns. When flying above the freezing level, hail can be expected in regions above and around wet storm cells found at lower altitudes. The hail is carried up to the tropopause by strong vertical winds inside the storm. In large storms, these winds can easily exceed 200 kt, making them very dangerous. Since the core of such a storm is very turbulent, but largely icy, the red core on the radar display is weak or absent and highly mobile. The storm core can be expected to change shapes with each antenna scan.

PRIMUSr 880 Digital Weather Radar System

On reaching the tropopause, the hail is ejected from the storm and falls downward to a point where it is sucked back into the storm. When the hail falls below the freezing level, however, it begins to melt and form a thin surface layer of liquid detectable by radar. A slight downward tilt of the antenna toward the warmer air shows rain coming from unseen dry hail that is directly in the flightpath, as shown in figure 5- 36. At lower altitudes, the reverse is sometimes true; the radar may be scanning below a rapidly developing storm cell, from which the heavy rain droplets have not had time to fall through the updrafts to the flight level. Tilting the antenna up and down regularly produces the total weather picture.

Using a tilt setting that has the radar look into the area of maximum reflectivity (5000 to 20,000 ft) gives the strongest radar picture. However the tilt setting must not be left at this setting. Periodically, the pilot should look up and down from this setting to see the total picture of the weather in the flightpath.

Often, hailstorms generate weak but characteristic patterns like those shown in figure 5- 37. Fingers or hooks of cyclonic winds that radiate from the main body of a storm usually contain hail. A U shaped pattern is also (frequently) a column of dry hail that returns no signal but is buried in a larger area of rain that does return a strong signal. Scalloped edges on a pattern also indicate the presence of dry hail bordering a rain area. Finally, weak or fuzzy protuberances are not always associated with hail, but should be watched closely; they can change rapidly.

DRY HAIL

BEAM IN

DOWNWARD

TILT POSITION

WET HAIL

AND RAIN

AD- 12059- R1@

Rain Coming From Unseen Dry Hail

Figure 5- 36

PRIMUSr 880 Digital Weather Radar System

AD- 35713@

Familiar Hailstorm Patterns

Figure 5- 37

The more that is learned about radar, the more the pilot is an all- important part of the system. The proper use of controls is essential to gathering all pertinent weather data. The proper interpretation of that data (the displayed patterns) is equally important to safety and comfort.

This point is illustrated again in figure 5- 38. When flying at higher altitudes, a storm detected on the long- range setting can disappear from the display as it is approached. The pilot should not be fooled into believing the storm has dissipated as the aircraft approaches it. The possibility exists that the radiated energy is being directed from the aircraft antenna above the storm as the aircraft gets closer. If this is the case, the weather shows up again when the antenna is tilted downward as little as 1_. Assuming that a storm has dissipated during the approach can be quite dangerous; if this is not the case, the turbulence above a storm can be as severe as that inside it.

PRIMUSr 880 Digital Weather Radar System

OVERFLYING A STORM

HAIL

AD- 12061- R1@

Overshooting a Storm

Figure 5- 38

Another example of the pilot???s importance in helping the radar serve its safety/comfort purpose is shown in figure 5- 39. This is the blind alley or box canyon situation. Pilots can find themselves in this situation if they habitually fly with the radar on the short range. The short- range returns show an obvious corridor between two areas of heavy rainfall, but the long- range setting shows the trap. Both the near and far weather zones could be avoided by a short- term course change of about 45_ to the right. Always switch to long range before entering such a corridor.

PRIMUSr 880 Digital Weather Radar System

Azimuth Resolution

When two targets, such as storms, are closely adjacent at the same range, the radar displays them as a single target, as shown in figure 5- 38. However, as the aircraft approaches the targets, they appear to separate. In the illustration, the airplane is far away from the targets at position A. At this distance, the beam width is spreading. As the beam scans across the two targets, there is no point at which beam energy is not reflected, either by one target or the other, because the space between the targets is not wide enough to pass the beam width. In target position B, the aircraft is closer to the same two targets; the beam width is narrower, and the targets separate on the display.

AD- 35705@

Azimuth Resolution in Weather Modes

Figure 5- 40

PRIMUSr 880 Digital Weather Radar System

RADOME

Ice or water on the radome does not generally cause radar failure, but it hampers operation. The radome is constructed of materials that pass the radar energy with little attenuation. Ice or water increases the attenuation making the radar appear to have less sensitivity. Ice can cause refractive distortion, a condition characterized by loss of image definition. If the ice should cause reverberant echoes within the radome, the condition might be indicated by the appearance of nonexisting targets.

The radome can also cause refractive distortion, which would make it appear that the TILT control was out of adjustment, or that bearing indications were somewhat erroneous.

A radome with ice or water trapped within its walls can cause significant attenuation and distortion of the radar signals. This type of attenuation cannot be detected by the radar, even with REACT on, but it can, in extreme cases, cause blind spots. If a target changes significantly in size, shape, or intensity as aircraft heading or attitude change, the radome is probably the cause.

PRIMUSr 880 Digital Weather Radar System

5When flying at high altitudes, tilt downward frequently to avoid flying above storm tops.

Studies by the National Severe Storms Laboratory (NSSL) of Oklahoma have determined that thunderstorms extending to 60,000 ft show little variation of turbulence intensity with altitude.

Ice crystals are poor reflectors. Rain water at the lower altitudes produce a strong echo, however at higher altitudes, the nonreflective ice produces a week echo as the antenna is tilted up. Therefore, though the intensity of the echo diminishes with altitude, it does not mean the severity of the turbulence has diminished.

NOTE: If the TILT control is left in a fixed position at the higher flight levels, a storm detected at long range can appear to become weaker and actually disappear as it is approached. This occurs because the storm cell which was fully within the beam at 100 NM gradually passes out of and under the radar beam.

6When flying at low altitudes rotate tilt upward frequently to avoid flying under a thunderstorm.

There is some evidence that maximum turbulence exists at middle heights in storms (20,000 to 30,000 ft); however, turbulence beneath a storm is not to be minimized. However, the lower altitude may be affected by strong outflow winds and severe turbulence where thunderstorms are present. The same turbulence considerations that apply to high altitude flight near storms apply to low altitude flight.

7Avoid all rapidly moving echoes by 20 miles.

A single thunderstorm echo, a line of echoes, or a cluster of echoes moving 40 knots or more will often contain severe weather. Although nearby, slower moving echoes may contain more intense aviation hazards, all rapidly moving echoes warrant close observation. Fast moving, broken to solid line echoes are particularly disruptive to aircraft operations.

8Avoid, the entire cell if any portion of the cell is red or magenta by 20 NM.

The stronger the radar return, the greater the frequency and severity of turbulence and hail.

Severe Weather Avoidance Procedures

Table 5- 12 (cont)

PRIMUSr 880 Digital Weather Radar System

9Avoid all rapidly growing storms by 20 miles.

When severe storms and rapid development are evident, the intensity of the radar return may increase by a huge factor in a matter of minutes. Moreover, the summit of the storm cells may grow at 7000 ft/min. The pilot cannot expect a flightpath through such a field of strong storms separated by 20 to 30 NM to be free of severe turbulence.

10Avoid all storms showing erratic motion by 20 miles.

Thunderstorms tend to move with the average wind that exists between the base and top of the cloud. Any motion differing from this is considered erratic and may indicate the storm is severe. There are several causes of erratic motion. They may act individually or in concert. Three of the most important causes of erratic motion are:

1.Moisture Source. Thunderstorms tend to grow toward a layer of very moist air (usually south or southeast in the U.S.) in the lowest 1500 to 5000 ft above the earth???s surface. Moist air generates most of the energy for the storm???s growth and activity. Thus, a thunderstorm may tend to move with the average wind flow around it, but also grow toward moisture. When the growth toward moisture is rapid, the echo motion often appears erratic. On at least one occasion, a thunderstorm echo moved in direct opposition to the average wind!

2.Disturbed Wind Flow. Sometimes thunderstorm updrafts block winds near the thunderstorm and act much like a rock in a shallow river bed. This pillar of updraft forces the winds outside the storm to flow around the storm instead of carrying it along. This also happens in wake eddies that often form downstream of the blocking updraft

10 3. Interaction With Other Storms. A thunderstorm that is (cont) located between another storm and its moisture source may cause the blocked storm to have erratic motion.

Sometimes the blocking of moisture is effective enough to cause the thunderstorm to dissipate.

Severe Weather Avoidance Procedures

Table 5- 12 (cont)

PRIMUSr 880 Digital Weather Radar System

Three of the most common erratic motions are:

1.Right Turning Echo. This is the most frequently observed erratic motion. Sometimes a thunderstorm echo traveling the same direction and speed as nearby thunderstorm echoes, slows, and turns to the right of its previous motion. The erratic motion may last an hour or more before it resumes its previous motion. The storm should be considered severe while this erratic motion is in progress.

2.Splitting Echoes. Sometimes a large (20- mile or larger diameter) echo splits into two echoes. The southernmost echo often slows, turns to the right of its previous motion, and becomes severe with large hail and extreme turbulence.

If a tornado develops, it is usually at the right rear portion of the southern echo. When the storm weakens, it usually resumes its original direction of movement. The northern echo moves left of the mean wind, increases speed and often produces large hail and extreme turbulence.

3.Merging Echoes. Merging echoes sometimes become severe, but often the circulation of the merging cells interfere with each other preventing intensification. The greatest likelihood of aviation hazards is at the right rear section of the echo.

Severe Weather Avoidance Procedures

Table 5- 12 (cont)

PRIMUSr 880 Digital Weather Radar System

AD- 15560- R1@

Typical Hook Pattern

Figure 5- 42

The hooks are located at the right rear side of the thunderstorm echo???s direction of movement (usually the southwest quadrant).

The hook is not the tornado echo! A small scale low pressure area is centered at the right rear side of the thunderstorm echo near its edge. The low usually ranges from about 3 to 10 miles in diameter. Precipitation is drawn around the low???s cyclonic circulation to form the characteristic hook shape. Tornadoes form within the low near hook. According to statistics from the NSSL, almost 60 percent of all observed hook echoes have tornadoes associated with them. A tornado is always suspected when a hook echo is seen.

A hook can form with no tornadoes and vice versa. However, when a bona fide hook is observed on a weather radar, moderate or greater turbulence, strong shifting surface winds, and hail are often nearby and aircraft should avoid them.

PRIMUSr 880 Digital Weather Radar System

There are many patterns on radar that resemble hook echoes but are not associated with severe weather. Severe weather hook echoes last at least 5 minutes and are less than 25 miles in diameter. The favored location for hook echoes is to the right rear of a large and strong cell, however, in rare cases tornadoes occur with hooks in other parts of the cell.

AVOID V- NOTCH BY 20 MILES

A large isolated echo will sometimes have the configuration that is shown in figure 5- 43. This echo is called V- notch or flying eagle although some imagination may be needed by the reader to see the eagle. V- notch echoes are formed by the wind pattern at the leading edge (left front) of the echo. Thunderstorm echoes with V- notches are often severe, containing strong gusty winds, hail, or funnel clouds, but not all V- notches indicate severe weather. Again, severe weather is most likely at S in figure 5- 43.

V- Notch Echo, Pendant Shape

Figure 5- 43

PRIMUSr 880 Digital Weather Radar System

AVOID PENDANT BY 20 MILES

The pendant shape shown in figure 5- 44, represents one of the most severe storms - the supercell. One study concluded that, in supercells:

D The average maximum size of hail is over 2 inches (5.3 cm)

D The average width of the hail swath is over 12.5 miles (20.2 km)

D Sixty percent produce funnel clouds or tornadoes.

The classic pendant shape echo is shown in figure 5- 44. Note the general pendant shape, the hook, and the steep rain gradient. This storm is extremely dangerous and must be avoided.

STORM MOTION

AD- 35706@

The Classic Pendant Shape

Figure 5- 44

PRIMUSr 880 Digital Weather Radar System

AVOID STEEP RAIN GRADIENTS BY 20 MILES

Figure 5- 45 shows steep rain gradients. Refer to the paragraph, Interpreting Weather Radar Images, this section, for a detailed explanation of weather images.

Rain Gradients

Figure 5- 45

AVOID ALL CRESCENT SHAPED ECHOES BY 20 MILES

A crescent shaped echo, shown in figure 5- 46, with its tips pointing away from the aircraft indicates a storm cell that has attenuated the radar energy to the point where the entire storm cell is not displayed. This is especially true if the trailing edge is very crisp and well defined with what appears to be a steep rain gradient.

When REACT is selected, the area behind the steep rain gradient fills in with cyan.

PRIMUSr 880 Digital Weather Radar System

20 10

AD- 22161- R1@

Crescent Shape

Figure 5- 46

Line Configurations

AVOID THUNDERSTORM ECHOES AT THE SOUTH END OF A

LINE OR AT A BREAK IN A LINE BY 20 MILES

The echo at the south end of a line of echoes is often severe and so too is the storm on the north side of a break in line. Breaks frequently fill in and are particularly hazardous for this reason. Breaks should be avoided unless they are 40 miles wide. This is usually enough room to avoid thunderstorm hazards.

The above two locations favor severe thunderstorm formation since these storms have less competition for low level moisture than others nearby.

PRIMUSr 880 Digital Weather Radar System

AVOID LINE ECHO WAVE PATTERNS (LEWP) BY 20 MILES

One portion of a line may accelerate and cause the line to assume a wave- like configuration. Figure 5- 47 is an example of an LEWP. The most severe weather is likely at S. LEWPs form solid or nearly solid lines that are dangerous to aircraft operations and disruptive to normal air traffic flow.

Line Echo Wave Pattern (LEWP)

Figure 5- 47

The S indicates the location of the greatest hazards to aviation. The next greatest probability is anywhere along the advancing (usually east or southeast) edge of the line.

PRIMUSr 880 Digital Weather Radar System

Additional Hazards

TURBULENCE VERSUS DISTANCE FROM STORM CORE

The stronger the return, the further the turbulence will be encountered from the storm core at any altitude. Severe turbulence is often found in the tenuous anvil cloud 15 to 20 miles downwind from a severe storm core. Moreover, the storm cloud is only the visible portion of a turbulent system whose up and down drafts often extend outside of the storm proper.

TURBULENCE VERSUS DISTANCE FROM STORM EDGE

Severe clear- air turbulence can occur near a storm, most often on the downwind side. Tornadoes are located in a variety of positions with respect to associated echoes, but many of the most intense and enduring occur on the up- relative- windside. The air rising in a tornado can contribute to a downwind area of strong echoes, while the tornado itself may or may not return an echo. Echo hooks and appendages, though useful indexes of tornadoes, are not infallible guides.

The appearance of a hook warns the pilot to stay away, but just because the tornado cannot be seen is no assurance that there is no tornado present.

Expect severe turbulence up to 20 NM away from severe storms; this turbulence often has a well- defined radar echo boundary. This distance decreases somewhat with weaker storms that display less well- defined echo boundaries.

The last section of this manual contains several advisory circulars. It is recommended that the pilot become familiar with them.

PRIMUSr 880 Digital Weather Radar System

GROUND MAPPING

Ground mapping operation is selected with the GMAP button An example of ground map display is shown in figure 5- 49. Turn the TILT control down until the desired amount of terrain is displayed. The degree of down- tilt will depend upon the type of terrain, aircraft altitude, and selected range. Tables 5- 13 and 5- 5 show tilt settings for maximal ground target display at selected ranges.

Ground Mapping Display

Figure 5- 49

For the low ranges (5, 10, 25, and 50 NM), the transmitter pulsewidth is narrowed and the receiver bandwidth is widened to enhance the identification of small targets. In addition, the receiver STC characteristics are altered to better equalize ground target reflections versus range. As a result, the preset gain position is generally used to display the desired map. The pilot can manually decrease the gain to eliminate unwanted clutter.

PRIMUSr 880 Digital Weather Radar System

6.Maximum Permissible Exposure Level (MPEL)

Heating and radiation effects of weather radar can be hazardous to life. Personnel should remain at a distance greater than R from the radiating antenna in order to be outside of the envelope in which radiation exposure levels equal or exceed 10 mW/cm2, the limit recommended in FAA Advisory Circular AC No. 20--68B, August 8, 1980, Subject: Recommended Radiation Safety Precautions for Ground Operation of Airborne Weather Radar. The radius, R, to the maximum permissible exposure level boundary is calculated for the radar system on the basis of radiator diameter, rated peak--power output, and duty cycle. The greater of the distances calculated for either the far--field or near--field is based on the recommendations outlined in AC No. 20--68B. The advisory circular is reproduced without Appendix 1 in Appendix A of this guide.

The American National Standards Institute (ANSI), in their document

ANSI C95.1--1982, recommends an exposure level of no more than 5 mW/cm2.

Honeywell recommends that operators follow the 5 mW/cm2 standard. Figure 6--1 shows MPEL for both exposure levels.

MPEL Boundary

Figure 6--1

PRIMUSr 880 Digital Weather Radar System

7.In- Flight Troubleshooting

The PRIMUS?? 880 Digital Weather Radar System can provide troubleshooting information on one of two formats:

D Fault codes

D Text faults.

The selection is made at the time of installation. This section describes access and use of this information.

If the fault codes option is selected, they are shown in place of the tilt angle. The text fault option provides English text in the radar test pattern areas.

Critical functions in the receiver transmitter antenna (RTA) are continuously monitored. Each fault condition has a corresponding 2- digit fault code (FC). Additionally, a fault name, a pilot message, and a line maintenance message are associated with each fault condition.

Faults can be accessed on the ground, or while airborne. The following conditions indicate that fault information is being displayed:

D Display, indicator, or RTA malfunction

D FAIL annunciation on weather indicator or EFIS display.

If the feature TEXT FAULTS is enabled, the radar test pattern area will display plan English text fault information. If it is not enabled, only the fault code is shown (one at a time) on the indicator or EFIS display.

PRIMUSr 880 Digital Weather Radar System

NOTES: 1. FC installations with a radar indicator can display stored faults for the current power- on cycle and nine previous cycles. Installations with radar displayed on the electronic flight instrument system (EFIS) do not display stored faults.

2.In FC installation, that use a radar indicator, when the storage memory is full, the indicator fault storage deletes the oldest power- on fault codes to make room for the newest.

3.In EFIS installations, some weather failures are only annunciated with an amber WX.

4.In EFIS installations, with TEXT FAULTS enabled, the fault codes are also presented as part of the FAIL annunciation (e.g., FAIL 13).

Test Mode With TEXT FAULTS Enabled

Upon entering test mode, the most recent fault is displayed, cycling to the oldest fault in the eligible list of faults. Upon reaching the last fault an END OF LIST message is displayed. To recycle through the list again, exit and re- enter TEST mode.

PRIMUSr 880 Digital Weather Radar System

8.Honeywell Product Support

The Honeywell SPEXR program for corporate operators provides an extensive exchange and rental service that complements a worldwide network of support centers. An inventory of more than 9,000 spare components assures that the Honeywell equipped aircraft will be returned to service promptly and economically. This service is available both during and after warranty.

The aircraft owner/operator is required to ensure that units provided through this program have been approved in accordance with their specific maintenance requirements.

All articles are returned to Reconditioned Specifications limits when they are processed through a Honeywell repair facility. All articles are inspected by quality control personnel to verify proper workmanship and conformity to Type Design and to certify that the article meets all controlling documentation. Reconditioned Specification criteria are on file at Honeywell facilities and are available for review. All exchange units are updated with the latest performance reliability MODs on an attrition basis while in the repair cycle.

For more information regarding the SPEX program, including maintenance, pricing, warranty, support, and access to an electronic copy of the Exchange/Rental Program for Corporate Operators, Pub. No. A65--8200--001, you can go to the Honeywell web site at: http://www.avionicsservices.com/home.jsp

PRIMUSr 880 Digital Weather Radar System

CUSTOMER SUPPORT

Honeywell Aerospace Online Technical Publications

Web Site

Go to the Honeywell Online Technical Publications Web site at https://pubs.cas.honeywell.com/ to:

D Download or view publications online D Order a publication

D Tell Honeywell of a possible data error in a publication.

Customer Response Center (CRC)

If you do not have access to the Honeywell Online Technical Publications Web site, send an e--mail message or a fax, or speak to a person at the CRC:

Also, the CRC is available if you need to:

D Identify a change of address, telephone number, or e--mail address D Make sure that you get the next revision of this guide.

PRIMUSr 880 Digital Weather Radar System

Appendix A

Federal Aviation Administration

(FAA) Advisory Circulars

NOTE: This section contains a word- for- word transcription of the contents of the following FAA advisory circulars:

D AC 20- 68B

D AC 00- 24B.

SUBJECT: RECOMMENDED RADIATION SAFETY

PRECAUTIONS FOR GROUND

OPERATION OF AIRBORNE WEATHER

RADAR

Purpose

This circular sets forth recommended radiation safety precautions to be taken by personnel when operating airborne weather radar on the ground.

Cancellation

AC 20- 66A, dated April 11, 1975, is cancelled.