WEATHER RADAR SYSTEM - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
The aircraft is equipped with the Collins Multiscan Weather Radar (WXR) transceiver with the Predictive Windshear System (PWS).This system is compatible with Electronic Instrument System (EIS) 1 and 2, and complies with Aeronautical Radio Incorporated (ARINC) characteristics 708A.
Multiscan is a radar function that displays all significant weather conditions at all ranges, at all aircraft altitudes, and at all times on a display that is essentially clutter-free, without the need for pilots to input tilt or gain settings. This function reduces pilot workload while enhancing weather detection capability.
The multiscan function determines the optimum tilt angle for the radar through monitoring of:

The aircraft altitude
The aircraft attitude
The aircraft position.

Two antenna scans are performed, each scan is optimized for a particular region in front of the aircraft. With the use of these 2 beams, the system is able to eliminate ground clutter efficiently and to emulate an ideal beam, which accounts for earth curvature and provide long range weather depiction. The upper beam detects the medium-range weather conditions and the lower beam detects the short and long-range weather conditions by automatically adjusting the tilt and gain. The information from the system is stored in a temporary database. When the Captain (CAPT) or the First Officer (F/O) selects a range, the WXR transceiver retrieves the appropriate information by merging the data and eliminates the ground clutter. The result is an optimized weather display for the flight crew to select the required range scale.

The WXR/PWS enables:

The detection and localization of atmospheric disturbances in the area defined by the antenna scanning (+/- 90° of the aircraft centerline and up to 320NM in front of the aircraft)
The detection of turbulence areas caused by precipitations up to a distance of 40NM
The presentation of terrain mapping information by the combination of the radar beam and the receiver gain orientation
The detection of a microburst windshear event in the area defined by the antenna scanning (+/- 60°).
The presentation of the windshear events within an area (+/- 30°) of the aircraft centerline and up to 5 NM in front of the aircraft.

NOTE: A microburst is a cool shaft of air like a cylinder, between 1000 and 3000 ft. When it encounters the ground (airflow velocity from 40 to 110 kts), the downward airflow is changed to horizontal flow (from 80 to 220 kts) at the base of the air shaft. There are two types of microburst, wet and dry.

Five color displays are used to show precipitation, turbulence and ground mapping to the crew.
The location of the windshear events is indicated by an icon (symbol consisting of alternating red and black arcs).
The aircraft is equipped with an X-band dual Collins WXR-2100 Multiscan Radar transceiver P/N 822-1710-202 with Predictive Windshear System (PWS). This system is compatible with Electronic Instrument System 1 and 2 (EIS1 and EIS2) and complies with ARINC Characteristics 708A.
Multiscan is a radar function that displays all significant weather at all ranges, at all aircraft altitudes, and at all times on a display that is essentially clutter-free, without the need for pilots to input tilt or gain settings. Multiscan reduces pilot workload while enhancing weather detection capability.
The Multiscan function optimizes weather detection and minimizes ground clutter. This function determines the optimum tilt angle for the radar through monitoring of:

The aircraft altitude above the terrain (RA and ADR information).
The aircraft position (IR information).
The terrain conditions in the area (information located in an interval "Reference table").

Two antenna scans are performed, each scan is optimized for a particular region in front of the aircraft. The upper beam detects medium-range weather and the lower beam detects short and long-range weather by automatically adjusting tilt and gain. The information is then stored in a temporary database. When the captain or the first officer selects a range, the weather radar transceiver retrieves the appropriate portions of the desired information, merges the data and then eliminates ground clutter. The result is an optimized weather display and the flight crew selects the range scale required.

In the following text, the abbreviation WXR/PWS is used.
The WXR/PWS enables:
Detection and localization of the atmospheric disturbances in the area defined by the antenna scanning: plus or minus 90 deg. of aircraft centerline and up to 320NM in front of the aircraft
Detection of turbulence areas caused by the presence of precipitations up to a distance of 40NM
Presentation of terrain mapping information by the combination of the orientation of the radar beam and of the receiver gain
Detection of a microburst windshear event in the area defined by the antenna scanning: plus or minus 60 deg.
Presentation of windshear events within an area plus or minus 30 deg. of aircraft centerline and up to 5NM in front of the aircraft.

NOTE: A microburst is a cool shaft of air, like a cylinder, between 1000 and 3000 ft. When it encounters the ground (airflow velocity from 40 to 110 kts) the downward moving airflow is translated to a horizontal flow (from 80 to 220 kts), at the base of the air shaft. Two types of microburst exist, wet and dry.

Five color displays are used to show precipitations, turbulence and ground mapping to the crew.
The location of the windshear events is indicated by an icon (symbol consisting of alternating red and black arcs).

** ON A/C NOT FOR ALL

2. Component Location

Weather Radar - Component Location ** ON A/C NOT FOR ALL

Weather Radar - Control and Indicating ** ON A/C NOT FOR ALL

Weather Radar - Component Location ** ON A/C NOT FOR ALL

Weather Radar - Control and Indicating ** ON A/C NOT FOR ALL

Weather Radar - Component Location ** ON A/C NOT FOR ALL

Weather Radar - Control and Indicating ** ON A/C NOT FOR ALL

The components of the weather radar system are located in the aircraft as follows:

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C NOT FOR ALL
1SQ1	XCVR-WEATHER RADAR, 1	109VU	121	34-41-33
3SQ	CTL UNIT-WEATHER RADAR	11VU	210	34-41-12
7SQ	DRIVE-WR ANTENNA		110	34-41-11
9SQ	MTG TRAY-WR XCVR	109VU	121	34-41-37
** ON A/C NOT FOR ALL
11SQ	ANTENNA-WEATHER RADAR	110AL	110	34-41-11
** ON A/C NOT FOR ALL
11SQ	ANTENNA-WEATHER RADAR		110	34-41-11
** ON A/C NOT FOR ALL
1SQ2	XCVR-WEATHER RADAR, 2	109VU	121	34-41-33

** ON A/C NOT FOR ALL

3. System Description

Weather Radar Block Diagram - Data Acquisition ** ON A/C NOT FOR ALL

Weather Radar Block Diagram - Control and Display ** ON A/C NOT FOR ALL

The WXR/PWS is composed of items closely associated with its operation such as peripherals supplying parameters, Electronic Flight Instrument System (EFIS) display units (DUs) or maintenance functions.

NOTE: The WXR image is shown on the CAPT and F/O Navigation Displays (NDs).
The NDs are connected to three Display Management Computers (DMCs) and to the CAPT and F/O EFIS control sections of the Flight Control Unit (FCU).

NOTE: The three Air Data/Inertial Reference Units (ADIRUs) give air data information to the WXR system. This data is used for the radar antenna stabilization and for the computations of the windshear function.

Weather Radar Block Diagram - Data Acquisition ** ON A/C NOT FOR ALL

Weather Radar Block Diagram - Control and Display ** ON A/C NOT FOR ALL

The WR/PWS is composed of items closely associated with its operation, such as peripherals supplying parameters, EFIS display units or maintenance functions.

NOTE: The weather radar image is shown on the CAPT and F/O Navigation Displays (ND).
The NDs are connected to the three Display Management Computers (DMC) and to the CAPT and F/O EFIS control panels of the FCU.

NOTE: The three ADIRUs give data information to the weather radar system. These data ensure the radar antenna stabilization and the computations of the windshear function.

A. General
The Weather radar system consists of:

A transceiver 1SQ1
A control unit 3SQ
An antenna drive 7SQ
An antenna 11SQ
A transceiver single mounting tray 9SQ with a wave guide.

The weather radar system, which complies with ARINC Characteristics 708A, consists of:

Two transceivers 1SQ1, 1SQ2,
A dual control unit 3SQ,
A dual antenna drive 7SQ,
An antenna plate 11SQ,
A transceiver dual mounting tray 9SQ with a wave guide switch.

(1) Weather radar transceiver
The transceiver is the heart of the WXR/PWS system. The additional necessary wiring and interfaces enable the transceiver to operate as a PWS system. The receiver signal is formatted into 1600-bit ARINC 453 words and sent to the DMCs.
The transceiver ensures the following functions:

Generation of very short intense pulses of microwave energy via an X-band wave guide to the antenna and the processing of their echoes (radio frequency signals) to obtain the desired information
Acquisition of data from the Radio Altimeters (RA1 and RA2) and other specific interfaces
Windshear event detection and generation of the appropriate signal
Built-In Test Equipment (BITE) function of the system.

(2) Weather Radar Transceiver
The receiver-transmitter is the heart of the WR/PWS system, the additional necessary wiring and interfaces enable the weather radar transceiver to operate as a PWS (WR/PWS).
The receiver-transmitter ensures the following functions:

Generation of the very short intense pulses of microwave energy via an X-band wave guide to the antenna, and the processing of their echoes (radio frequency signals) to obtain the desired information,
The receiver signal is formatted into 1600-bit ARINC 453 words and sent to the Display Management Computers (DMCs),
Acquisition of data from Radio Altimeters (RA1 and RA2) and other specific interfaces,
Windshear event detection and generation of the appropriate signal,
BITE function of the system.

(3) Weather radar control unit
The control unit generates a 32-bit (label 270) serial control word which describes the selected operating modes (1/OFF/2, WX, WX + T, TURB, MAP, PWS, GCS, MULTISCAN, GAIN and TILT).
The WXR/PWS receives one ARINC 429 bus coming from the control unit.
Moreover, the PWS function can be deactivated if the PWS does not operate correctly.

(4) WR antenna drive
The WXR/PWS has one antenna drive which is the interface of the transceiver to control and monitor the azimuth and elevation of the antenna.

(5) Weather radar antenna
The antenna is used for transmitting and receiving radar radio frequency signals.

(6) Transceiver mounting tray with a wave guide
The mounting tray allows to install the transceiver on the aircraft rack and connects the transceiver to the wave guide.

(7) Weather Radar dual Control Unit
The control unit generates a 32-bit (label 270) serial control word which describes the selected operating modes (1/OFF/2, WX, WX + T, TURB, MAP, PWS, GCS, MULTISCAN, GAIN TILT).
The WR/PWS receives one ARINC 429 bus coming from the control unit.
Moreover, the predictive windshear function can be de-activated if the PWS does not operate correctly.

(8) WR Antenna Drive
The WXR/PWS has one dual antenna drive which is the interface of each transceiver to control and monitor the azimuth and elevation of the antenna.

(9) Weather Radar Antenna
The antenna is used for transmitting and receiving radar radio frequency signals.

(10) Transceiver Dual Mounting Tray with a Wave Guide
It allows to install each transceiver on the aircraft rack and connects the activated transceiver to the wave guide.

(11) General Information
The WXR image is shown on the CAPT and F/O NDs. The windshear warning is shown on the CAPT and F/O Primary Flight Displays (PFDs) and on the upper Electronic Centralized Aircraft Monitoring (ECAM) DU. The NDs and PFDs are connected to the three DMCs and to the CAPT and F/O EFIS control sections of the FCU.
The parameters given by the ADIRUs to the WXR system are as follows:

The altitude and the True Airspeed (TAS) information (Ref. AMM D/O 34-13-00-00)
The attitude, ground speed, magnetic heading, true heading, east/west velocity, north/south velocity, track angle and drift angle (Ref. AMM D/O 34-14-00-00).
This data is used for the radar antenna stabilization and for the corrections of the Doppler mode (turbulence).

(12) General information

NOTE: The weather radar and windshear detection image (if the predictive windshear function is activated) is shown on the Captain and First Officer Navigation Displays (ND) and the windshear warning is shown on Captain and First Officer Primary Flight Displays (PFD) and on the upper ECAM DU. The NDs and PFDs are connected to the three Display Management Computers (DMC) and to the Captain and First Officer EFIS control sections of the FCU.

NOTE: If the Enhanced GPWS is operative, the WR image is replaced by the terrain image, on the Captain and First Officer NDs, during a terrain alert or a crew action.
More explanations are given in 34-48.

NOTE: The ADIRUs give to the weather radar system:

The altitude and the true airspeed (TAS) information (Ref. AMM D/O 34-13-00-00),
The attitude, ground speed, magnetic heading, true heading, E/W velocity, N/S velocity, track angle and drift angle (Ref. AMM D/O 34-14-00-00).
These data ensure the radar antenna stabilization and the corrections of the Doppler mode (turbulence).

B. Peripherals

(1) Digital serial data inputs
The transceiver receives digital serial data inputs from the following components:

(a) Radio Altimeter
The radio altimeter provides altitude information over two ARINC 429 bus inputs to the WXR/PWS (label 164).
This data is used for automatic activation of the windshear function.
The second bus is for redundancy.

(b) Air Data Reference (ADR)
Two ARINC 429 low-speed buses provide:

TAS data (label 210) used for velocity calculations
Altitude data (label 203) used for sensitivity time control calculations
Corrected altitude data (label 206).

Pitch (label 324) and roll (label 325) data for stabilization and control of the antenna
East/west velocity (label 367) and north/south velocity (label 366) used for velocity calculations
Ground speed (label 312) used for velocity calculations
Track angle (label 317) used for velocity calculations
True heading (label 314)
Magnetic heading (label 320)
ADIRU align mode (label 270).

NOTE: The main air data and heading altitude data are provided by the Air Data/Inertial Reference System (ADIRS).

(d) Centralized Fault Display Interface Unit (CFDIU)
The WXR/PWS communicates with the CFDIU low-speed ARINC 429 buses.

(e) EFIS control sections
Two ARINC 429 buses provide the CAPT and F/O range selection (label 271).
The transceiver receives one bus from the CAPT EFIS control section and another from the F/O EFIS control section.

(2) Digital serial data inputs
The transceiver receives digital serial data inputs from the following components:

(a) Radio Altimeter
The Radio Altimeter provides altitude information over two ARINC 429 bus inputs to the WR/PWS (label 164).
This data is used for automatic activation of the windshear function.
The second bus is for redundancy.

(b) Air Data Reference
Two ARINC 429 low-speed buses provide:

True airspeed data (label 210) used for velocity calculations
Altitude data (label 203) used for sensitivity time control (STC) calculations
Corrected altitude data (label 206).

Pitch (label 324) and roll (label 325) data for the stabilization and control of the antenna
East/west velocity (label 367) and north/south velocity (label 366) used for velocity calculations
Ground speed (label 312) used for velocity calculations and qualifiers C1, C2
Track angle (label 317) used for velocity calculations
True heading (label 314)
Magnetic heading (label 320)
Body longitudinal acceleration (label 331) used for qualifiers D1, D2.

NOTE: The main air data and heading altitude data are provided by the Air Data/Inertial Reference System (ADIRS).

(d) Centralized Fault Display Interface Unit (CFDIU)
The WR/PWS communicates with the CFDIU low-speed ARINC 429 buses.

(e) EFIS Control Section
Two ARINC 429 buses provide the CAPT and F/O range selection (label 271).
The receiver/transmitter receives one bus from the CAPT EFIS control section and another one from the F/O EFIS control panel.

(f) One ARINC 429 high-speed bus (Hazard) provides radar data to be recorded on the Flight Data Interface and Management Unit (FDIMU).

(g) One ARINC 429 high-speed bus (Hazard) provides radar data to the Enhanced Ground Proximity Warning System (EGPWS).

(3) Discrete inputs
The transceiver receives the following discrete inputs:

(a) Ground/flight signal and landing gear extended signal
These signals are provided by the Landing Gear Control and Interface Unit (LGCIU).

The ground/flight signal is used to determine the identifying flight phase for the BITE test.
The landing gear extended signal is used to determine transition from the landing mode to the takeoff mode, to identify a GO AROUND condition. In this case the appropriate aural message is generated.

(b) Qualifier B, C, D signals (new qualifier logic/qualifier A: ATC is no more used)
Two types of qualifier inputs are used to control automatic activation of the windshear function (B and C or B and D).

Qualifiers B: Two qualifier B inputs are used. These input signals are provided by the engine oil pressure sensors indicating when there is normal operating pressure.
Qualifier B1 is connected to engine 1 and qualifier B2 is connected to engine 2.
Qualifier B2 is for redundancy.
Qualifiers B1 and B2 are connected to the transceiver.
Qualifiers C: Two qualifier C inputs are used.
Qualifier C1: Ground speed (label 312 provided by IR bus from IR1) (valid when GS > 30Kts).
Qualifier C2: Ground speed (label 312 provided by IR bus from IR3) (valid when GS > 30Kts).
Qualifiers D: Two qualifier D inputs are used.
Qualifier D1: Body longitudinal acceleration (label 331 provided by IR bus from IR1) (valid when Nx > 0.07g for at least 0.5 seconds).
Qualifier D2: Body longitudinal acceleration (label 331 provided by IR bus from IR3) (valid when Nx > 0.07g for at least 0.5 seconds).

To automatically activate the windshear function, one of the qualifiers B and one of the qualifiers C or D have to be valid.

(c) Windshear function enable signal
This discrete input provided by the weather radar control unit through the AUTO/OFF switch, activates the windshear function. This discrete signal is also transmitted to the DMCs which use it for the logic of windshear messages displayed.

(d) Windshear BITE enable signal
This discrete input allows the WXR/PWS to manage the BITE windshear failures sent to the CFDIU.

(4) Discrete Inputs
Each transceiver receives the following discrete inputs:

(a) Ground/flight signal and landing gear extended signal. These signals are provided by the Landing Gear Control and Interface Unit (LGCIU).

Ground/flight signal is used to determine the identifying flight phase for BITE
Landing gear extended signal is used to determine transition from landing mode to takeoff mode to identify a GO AROUND condition. In this case the appropriate aural message is generated.

(b) Qualifiers B, C, D signals (new qualifier logic/qualifier A: ATC is no more used).
Two types of qualifier inputs are used to control automatic activation of the windshear function (B and C or B and D).

Qualifiers B: two qualifiers B inputs are used. These input signals are provided by the engine oil pressure sensors indicating when there is normal operating pressure.
The qualifier B1 is connected to engine 1 and the qualifier B2 is connected to engine 2.
The qualifier B2 is for redundancy.
Qualifiers B1 and B2 are connected to transceivers 1 and 2.
Qualifiers C: two qualifiers C inputs are used.
Qualifier C1: ground speed (label 312 provided by IR bus from IR1) (valid when GS > 30Kts).(Ref. asterisk below)
Qualifier C2: ground speed (label 312 provided by IR bus from IR3) (valid when GS > 30Kts).
Qualifiers D: two qualifiers D inputs are used.
Qualifier D1: body longitudinal acceleration (label 331 provided by IR bus from IR1) (valid when Nx > 0.07g for at least 0.5 seconds).(Ref. asterisk below)
Qualifier D2: body longitudinal acceleration (label 331 provided by IR bus from IR3) (valid when Nx > 0.07g for at least 0.5 seconds).
(*) For the second transceiver, C1 and D1 information is provided by IR2.

To automatically activate the windshear function, one of the qualifiers B and one of the qualifiers C or D have to be valid.

(c) Windshear function enable signal
This discrete input provided by the weather radar control unit through switch AUTO/OFF enables the windshear function. This discrete signal is also transmitted to the DMCs which use it for the logic of windshear messages displayed.

(d) Windshear BITE enable signal
This discrete input allows the WXR/PWS to manage the BITE windshear failures sent to the CFDIU.

(5) Outputs
The transceiver provides the following outputs:

(a) Displays
The WXR/PWS is connected to the DMCs by an ARINC 453 bus to transmit the weather radar data and the windshear data (if the PWS function is activated) on the data word of label 055.
All the weather and windshear data received by the DMCs are processed to display the weather radar image and the windshear events on the EIS display units.

1 The ND provides the following indications:

WXR image
Windshear events location for advisory, caution or warning alert
Windshear failures.

2 The PFD provides all the visual alerts for caution or warning alert.

NOTE: The Flight Warning Computers (FWC) and the Flight Data Interface Unit (FDIU) receive the WXR/PWS data through the DMCs. This data is used by the FWCs to display the windshear function failure and deactivation.
The FDIU records the windshear alert and failure.

(b) Centralized Fault Display System (CFDS)
The WXR/PWS is connected to the CFDS to transmit the following words:

Label 354: Line Replaceable Unit (LRU) identification Part Number (P/N) and Serial Number (S/N) (coded in ISO5)
Label 356: Fault message (coded in ISO5)
Label 377: Equipment identification.

(c) Audio mixing box (if the PWS function is activated)
An analog audio output allows to transmit the aural windshear alert (synthetic voice message) to an audio mixing box connected to the loud speakers.

(d) Enhanced Ground Proximity Warning System (Enhanced GPWS) (optional)
The Enhanced GPWS receives WXR/PWS alerts from WXR1 hazard bus and WXR2 hazard bus (when the second transceiver is installed) to determine the alert priorities.
The PWS alerts override a terrain display and revert to the WXR display with the corresponding windshear data.
The alert priorities between the WXR/PWS and the Enhanced GPWS have been defined as follows:
1- WXR/PWS Warning
2- WXR/PWS Caution
3- Terrain Warning
4- Terrain Caution
5- WXR/PWS advisory (no audio)
6- Terrain background (no audio).

(e) Flight Data Interface and Management Unit (FDIMU)
One ARINC 429 high-speed bus (hazard) provides radar data to be recorded in the FDIMU.

(6) Outputs
The transceiver provides the following outputs:

(a) Displays
The WR/PWS is connected to the DMCs by an ARINC 453 bus to transmit the weather radar data and windshear data (if predictive windshear function is activated) on the data word of label 055.
All the weather and windshear data received by the DMCs are processed to display weather radar image and windshear events by the Electronic Instrument System (EIS).

1 The Navigation Display (ND) it provides the following indications:

Weather radar image
Windshear events location for advisory, caution or warning alert
Windshear failures.

2 The Primary Flight Display (PFD) it provides all visual alerts for caution or warning alert.

NOTE: The Flight Warning Computers (FWC) and the FDIU receive WR/PWS data through the DMCs. These data are used by the FWCs to display windshear function failure and windshear function de-activation.
The FDIU records the windshear alert and failure.

(b) Centralized Fault Display System (CFDS)
The WR/PWS is connected to the CFDS to transmit the following words:

Label 354: LRU identification P/N and S/N (coded in ISO5)
Label 356: fault message (coded in ISO5)
Label 377: equipment identification.

(c) Audio Mixing Box (if predictive windshear function is activated)
An analog audio output allows to transmit the aural alert windshear (synthetic voice message) to an audio mixing box connected to loud speakers.

(d) Enhanced Ground Proximity Warning System (Enhanced GPWS) (optional)
The Enhanced GPWS receives WR/PWS alerts from WXR1 Hazard bus and WXR2 Hazard bus (when the second transceiver is installed) to determine the alert priorities.
Predictive Windshear alerts override a terrain display and revert to the WR display with the corresponding windshear data.
The alert priorities between the WR/PWS and the Enhanced GPWS have been defined as follows:
1- WR/PWS Warning,
2- WR/PWS Caution,
3- Terrain Warning,
4- Terrain Caution,
5- WR/PWS advisory (no audio),
6- Terrain background (no audio).

(e) Flight Data Interface and Management Unit (FDIMU)
One ARINC 429 high speed bus (hazard) provides radar data to be recorded on FDIMU.

(f) Windshear function enable signal
This discrete input provided by the radar control box through AUTO/OFF switch enables the windshear function. This discrete signal is also transmitted to the DMCs which use it for the logic of windshear messages displayed.

(7) Audio inhibit discrete signals
These discrete signals are used to indicate whether the aural alert output has to be active or not:

The PWS aural alerts (audio inhibit discrete input) are inhibited by the reactive windshear system and stall warning.
The PWS audio inhibit discrete output is used to inhibit other aural alerts generated by systems such as the Traffic Alert and Collision Avoidance System (TCAS) or the Ground Proximity Warning System (GPWS) or other FWC warnings.
This inhibition occurs each time there is a PWS aural alert.

(8) Audio Inhibit Discrete Signals (if predictive windshear function is activated)
These discretes are used to indicate whether the aural alert output has to be active or not:

Predictive windshear aural alerts (audio inhibit discrete input) are inhibited by the Reactive Windshear System and stall warning.
Predictive windshear audio inhibit discrete output is used to inhibit other aural alerts generated by systems such as: Traffic Alert and Collision Avoidance System (TCAS) or Ground Proximity Warning System (GPWS) or other FWC warnings.
This inhibition occurs each time there is a PWS aural alert.

(9) Pin Programming (PIN PROG)

Audio level program pins set the audio output level of the synthetic voice for windshear aural alert
Qualifier polarity PIN PROG: This PIN PROG indicates the validity of the signal for both qualifiers
CFDIU interface PIN PROG: This program is activated when the second WXR/PWS is installed on the aircraft
Caution alert audio program: Two PIN PROG are provided to select the type of windshear caution aural alert
The MONITOR RADAR DISPLAY synthetic voice is generated instead of the chime
The Windshear function is activated through PIN PROG.
The windshear function BITE sends a signal to the CFDIU when there is a failure of the PWS function.

(10) Pin Programming (if predictive windshear function is activated)

Audio level program pins set the audio output level of the synthetic voice for windshear aural alert.
SDI (Source Destination Identification Encoder) program pins encode the location of the WR/PWS unit on the aircraft when two transceivers are installed.
Qualifier polarity program pins: for both qualifiers, this pin program indicates the validity of the signal.
CFDIU interface program pins: when the second WR/PWS is installed on the aircraft, this program pin is activated. The WR/PWS can communicate with the CFDIU.
Caution alert audio program: two program pins are provided to select the type of windshear caution aural alert.
The MONITOR RADAR DISPLAY synthetic voice is generated instead of the chime.
Windshear function enable program pins is used to activate the windshear function.
Windshear function bite enable signal allows to send to CFDIU failure related to the predictive windshear function.

C. General Technical Characteristics
The WXR/PWS system is mainly used to detect and localize various types of atmospheric disturbances and windshear events in the area scanned by the antenna. The system shows the disturbance intensity through the use of colors which vary with the atmospheric precipitation rate.
The disturbances are shown to the crew members on the NDs with different colors:

Black, Green, Yellow and Red to quantify the precipitation rates
Magenta to represent the turbulence areas up to 40 NM.

The system can show the location of the windshear events via the NDs:
alternating black and red arcs depict the windshear event.
As the minimum display range is 10 NM, two yellow radials appear at the edges and start beyond the windshear event.

** ON A/C NOT FOR ALL

4. Power Supply
Energization of the system is done through 115VAC/400 Hz bus:

1XP via the sub-busbar 101 XP-C for the transceiver.

Energization of the weather radar control unit and the WXR antenna drive is done through the transceiver.
The power consumption of the transceiver is 145 W maximum.
Energization of the system is through a 115VAC/400 Hz bus:

1XP via the sub-busbar 101 XP-C for transceiver 1,
2XP via the sub-busbar 202 XP-A for transceiver 2.

Energization of the weather radar control unit and of the WR antenna drive is through the selected transceiver.
Consumption of the transceiver is 145 W maximum.
The system is supplied through this circuit breaker:

A. Circuit Breaker Table

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	COM NAV/RADAR/1	5SQ1	K13
** ON A/C NOT FOR ALL
121VU	COM NAV/RADAR/2	5SQ2	K14
** ON A/C NOT FOR ALL
121VU	COM NAV/RADAR/2	5SQ2	K14

** ON A/C NOT FOR ALL

5. Interface

A. Digital Interface
The weather radar data is transmitted via ARINC 429 and 453 buses in compliance with ARINC 708A.
The table below contains all the output parameters in digital form.

-------------------------------------------------------------------------------

| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

-------------------------------------------------------------------------------

-------------------------------------------------------------------------------

! 055 ! WXR DATA ! ! ! !1600!7.82! DIS! ! !

! ! ! ! ! ! ! ! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

! 270 ! CONTROL ! ! ! ! 32 !100 ! DIS! ! !

! ! WORD 1 ! ! ! ! ! ! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

! 271 ! CONTROL ! ! ! ! 32 !100 ! DIS! ! !

! ! WORD 2 ! ! ! ! ! ! ! ! !

!--------------!----------!------------!----!----!----!----!----!-----!-------!

! 356 ! Mainte- ! ! ! ! !100 !ISO5! ! !

! ! nance ! ! ! ! ! ! ! ! !

! ! message ! ! ! ! ! ! ! ! !

! ! word ! ! ! ! ! ! ! ! !

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(1) Control words (Labels 270 and 271)
The control words are transmitted to the control buses which connect the weather radar control unit to the transceiver.
Control word 1 (label 270) provides the following data:

Gain
Tilt angle
Selected mode
Stabilization (ON/OFF)
Scan angle (normal/reduced)
Anticlutter (ON/OFF) (optional)
Split function (Capt/Both/F/O) (optional).

Control word 2 (label 271) provides the following data:

Range
Anticlutter (ON/OFF) (optional)
The WXR selected on the EFIS control section (master/slave).

(2) Data word (Label 055)
The signals transmitted through the data bus line connect the WXR/PWS to the DMC and comply with the data word format (label 055) as defined by ARINC specification 708A (Appendix 15.2).
The data bus line transmits 190 data words per second. Each word is made up of 1600 bits sent on 1 Megabit/s frequency (ARINC specification 453) as per MANCHESTER II BI PHASE 2 format.

Weather Radar - Manchester II Biphase Format ** ON A/C NOT FOR ALL

The data word message includes mainly the radar return intensity and the windshear data.

-----------------------------------------------------------------------------

! BITS ! FUNCTION !

!----------!----------------------------------------------------------------!

! 1-8 ! Label 00101101 : 055 !

! 9-10 ! Control Accept !

! 11 ! Spare !

! 12 ! Windshear Caution !

! 13 ! Windshear Warning !

! 14 ! Turbulence Alert !

! 15 ! Tilt selection !

! 16 ! Anticlutter !

! 17 ! Sector Scan !

! 18 ! Stabilization Limits !

! 19 ! V2 on board !

! 20 ! Display Fault (not used) !

! 21 ! Calibration or Air Data Input !

! 22 ! Attitude Input !

! 23 ! Control or Heading Input !

! 24 ! Antenna !

! 25 ! R/T or Radio Altimeter !

! 26 ! Stabilization !

! 27-29 ! Mode !

! 30-36 ! Tilt Angle !

! 37-42 ! Gain !

! 43-48 ! Range !

! 49 ! Windshear External Input Fault !

! 50-51 ! Data Accept !

! 52-63 ! Scan Angle !

! 64 ! Windshear Failure !

! 65-1600 ! Range Bin Data !

-----------------------------------------------------------------------------

The WXR/PWS uses the "Space address usage" technology defined by the ARINC specification 708A for the transmission of information on the data bus lines. This is achieved by two different data bus lines, each associated with a control bus line from an EFIS control section of the FCU.
Data BUS 1 always transmits the data associated to the range selected on CAPT EFIS control section (side 1).
Data BUS 2 always transmits the data associated to the range selected on F/O EFIS control section (side 2).
The control and data bits of word label 055 are valid at any moment on both DATA BUSES, even if the range selected on sides 1 and 2 of the FCU are different.

** ON A/C NOT FOR ALL

6. Component Description

A. Weather Radar Transceiver FIN: 1-SQ-1 FIN: 1-SQ-2

Weather Radar - Architecture ** ON A/C NOT FOR ALL

Weather Radar Transceiver - Component Description ** ON A/C NOT FOR ALL

The weather radar transceiver with PWS is a completely solid-state airborne unit.
It contains:

(1) A power amplifier
A single 777.77 MHz multiplier drive signal is developed by the power amplifier. The power amplification of the transmit section is accomplished by splitting the power amplifier drive before recombining the signals into a single multiplier drive signal.

(2) A power multiplier
The power multiplier produces the 9333.24 MHz transmitter output signal from the single multiplier drive signal (from the power amplifier).
The multiplier drive signal is multiplied by 3 to produce a 2333.31 MHz signal. The 2333.31 MHz signal is then quadrupled to produce the 9333.24 MHz transmitter output signal.

(3) A duplexer/monitor
The transmitter output is coupled through a duplexer/monitor to the wave guide antenna feed through a 4-port circulator. The monitor circuits in the duplexer/monitor are used to monitor the output power level and develop a frequency loop error signal to correct the frequency level.
The monitor circuit also accepts a test signal which affects a portion of the reference signal to be injected into the receiver for the test calibration. The 4-port circulator also couples the Radio Frequency (RF) return from the wave guide antenna feed through the pre-amplifier to the receiver portion of the transceiver.

(4) A pre-amplifier
The pre-amplifier assembly performs the wave guide limiter functions (protects the mixer diodes from all high power pulses), contains a noise diode circuit and a 2-stage RF amplifier which provides +18dB of RF gain.

(5) A mixer
The mixer circuit processes the detected RF return signal by mixing it with the first local oscillator signal and amplifying the resultant intermediate frequency signal in the first intermediate frequency amplifier.
The first intermediate frequency amplifier provides 25dB amplification before the first intermediate frequency signal is applied to the second intermediate frequency amplifier.

(6) A second intermediate frequency amplifier
The second intermediate frequency amplifier completes the receiver amplification of the RF return signal. The output from the first IF is converted to 13.8888 MHz second IF signal by mixing it with the 152.77 MHz second local oscillator signal. The second IF signal is double-buffered and applied to a synchronous detector. The third local oscillator signal is phase-split to obtain one signal in phase with the transmitter frequency and one signal phase is shifted by 90°.

(7) A sampler
The sampler commands and controls the receive and transmit functions within the transceiver. A digital signal processor is used to control the transmitter timing and the receiver normalizer.

(8) A digital signal processor
The digital signal processor circuit card performs the weather processing, clutter identification, clutter filtering, velocity extraction and editing, hazard computation and hazard recognition algorithms. Command and control information is passed from the digital signal processor to the sampler through a dual port Random Access Memory (RAM).

(9) A Central Processing Unit (CPU)
Control of internal functions, antenna servo controls, monitoring of system operation and formatting the processed data is accomplished by the CPU. It uses a microprocessor and a stored program to execute the following major routines that control the transceiver and system operations:

Attitude routine, pitch and roll parameters for the stabilization routine
Stabilization routine, elevation position to the elevation maintenance routine
Scan maintenance routine, antenna scan drive
Elevation maintenance routine, antenna elevation drive control bus manager routine, determining correct control configuration
Problem control monitor routine, programming the internal data collection parameters of the transceiver
Data bus formatter routine, processing and assembling of the control message of serial data word which is sent to the EFIS.

(10) An input/output unit
All interface functions between the microprocessor of the CPU and the rest of the transceiver units in the system are provided by the input/output unit. The control word buses, digital and analog attitude buses, radio altitude inputs and discrete buses are connected to the multiplexer and shift register of the input/output unit. In addition, the input/output unit contains speech circuits for windshear hazard annunciation, the synchro-to-digital conversion circuits, discrete warning annunciation outputs, aural warning outputs and the remote turn-on circuits.

(11) A BITE monitor
The BITE monitor provides the BITE power supply voltages to the BITE functions and circuits, a power monitor for the detected transmitter output and an interconnect for various signals used throughout the transceiver.

(12) A power amplifier
A single 777.77 MHz multiplier drive signal is developed by the power amplifier. The power amplification of the transmit section is accomplished by splitting the power amplifier drive before recombining the signals into a single multiplier drive signal.

(13) A power multiplier
The power multiplier produces the 9333.24 MHz transmitter output signal from the single multiplier drive signal (from the power amplifier).
The multiplier drive signal is multiplied by 3 to produce a 2333.31 MHz signal. The 2333.31 MHz signal is their quadrupled to produce the 9333.24 MHz transmitter output signal.

(14) A duplexer/monitor
The transmitter output is coupled through a duplexer/monitor to the waveguide antenna feed through a 4-port circulator. Incorporated in the duplexer operation are monitor circuits to monitor the output power level and develop a frequency loop error signal for the correction of frequency chirp.
The monitor circuit also accepts a test signal which causes a portion of the reference signal to be injected into the receiver for test calibration. The 4-port circulator also couples the RF return from the waveguide antenna feed through the preamplifier to the receiver portion of the transceiver.

(15) A preamplifier
The preamplifier assembly perform the waveguide limiter functions (protects the mixer diodes from all high power pulses), contains a noise diode circuit and contains a 2-stage RF amplifier which provides +18dB of RF gain.

(16) A mixer
The mixer circuit processes the detected RF return signal by mixing it with the First local oscillator signal and amplifying the resultant Intermediate Frequency (IF) signal in the First IF amplifier.
The first IF amplifier provides 25dB amplification before the First IF signal is applied to the second IF amplifier.

(17) A second IF amplifier
The second IF amplifier completes the receiver amplification of the RF return signal. The output from the first IF is converted to the 13.8888 MHz second IF signal by mixing it with the 152.77 MHz second local oscillator signal. The second IF signal is double-buffered and applied to a synchronous detector. The third local oscillator signal is phase-split to obtain one signal in phase with the transmitter frequency and one signal phase shifted by 90 deg.

(18) A sampler
The sampler commands and controls the receive and transmit functions within the receiver-transmitter. A digital signal processor is used to control transmitter timing and receiver normalizer.

(19) A digital signal processsor
The digital signal processor circuit card performs the weather processing, clutter identification, clutter filtering, velocity extraction and editing, hazard computation and hazard recognition algorithms. Command and control information is passed from the digital signal processor to the sampler through a dual port RAM.

(20) A central processing unit
Control of internal functions, antenna servo controls, monitoring of system operation and formatting the processed data is accomplished by the central processing unit. It uses a microprocessor and a stored program to execute the following major routines that control the transceiver and system operations:

Attitude routine, providing pitch and roll parameters for the stabilization routine
Stabilization routine, providing elevation position to the elevation maintenance routine
Scan maintenance routine, providing antenna scan drive
Elevation maintenance routine, providing antenna elevation drive control bus manager routine, determining correct control configuration
Problem control monitor routine, programming the internal data collection parameters of the transceiver
Data bus formatter routine, processing and assembling the control message of the serial data word sent to the EFIS.

(21) An input/output unit
All interface functions between the microprocessor of the central processing unit and the rest of the transceiver and units in the system are provided by the input/output unit. Control word buses, digital and analog attitude buses, radio altitude inputs and discrete buses are all connected to the multiplexer and shift register of the input/output unit. In addition, the input/output unit contains speech circuits for windshear hazard annunciation, the synchro-to-digital conversion circuits, discrete warning annunciation outputs, aural warning outputs and remote turn-on circuits.

(22) A BITE/monitor
The BITE/monitor provides the BITE power supply voltages to BITE functions and circuits, a power monitor for the detected transmitter output and an interconnect for various signals used throughout the transceiver.

B. Weather Radar System

(1) Autotilt
The weather radar RDR-4B can operate in autotilt mode (automatic tilt angle): the use of the automatic tilt function is recommended in WX and TURB modes.

The autotilt function uses the terrain altitude information of the Enhanced GPWS. the Enhanced Ground Proximity Warning System (E-GPWS). Based on the aircraft altitude above the terrain and on terrain conditions in the area, the Enhanced GPWS determines the optimum tilt angle for the radar. This automatic tilt angle setting results in minimum ground clutter on the display while maintaining an optimum weather detection capability. One exception is the autotilt MAP mode, where the radar beam is intentionally aimed at the ground as a function of range.

NOTE: Manual tilt should be used when analyzing terrain and storm characteristics.

The autotilt function is integrated in the existing windshear submodes. On preparation for takeoff through 2300 feet, the weather scans alternate with the windshear scans. This occurs on approach, as well, below 2300 feet. The autotilt function controls the tilt only during weather scans. The windshear scan algorithm does not change with the autotilt functionality.

NOTE: When range settings are different (one display at a range of more than 80NM and the other display at a range of less than or equal to 80NM) the weather radar scans alternately to cover the different range settings.

The autotilt functionality is optimized for range settings less than or equal to 80NM (short range) and range settings more than 80NM (long range). If above 2300 feet AGL and if all displays are set to the same setting (either all short range or all long range), the weather display is updated in both directions clockwise (CW) and counterclockwise (CCW). If above 2300 feet AGL and if at least one display is on short range while the others are on long range, then the weather display is updated on alternate scans to account for the different autotilt settings required. Below 2300 feet AGL, the autotilt scans are based on short range tilt setting. There is no long range/short range alternate scanning in the windshear active region.

Weather Radar - Automatic Tilt Antenna Scan Pattern ** ON A/C NOT FOR ALL

The antenna scan is divided into five sectors/areas. The tilt angle displayed for each sector is calculated based on aircraft altitude, terrain height and range selection.

(2) Antenna Scan Pattern

Weather Radar - Manual Tilt/Automatic Tilt ** ON A/C NOT FOR ALL

Figure 009 shows the benefits of autotilt with manual tilt control: there can be over scan where the weather cells and the terrain are below the antenna beam and the display is blank, or under scan where the antenna scan is basically hitting the ground below the weather cells and the display contains only ground clutter. The integration of Enhanced GPWS and radar functionality (autotilt) provides a layer of protection against these extremes.

(3) Autotilt Selection
Automatic tilt is selected by setting the TILT (AUTO/MAN) switch to AUTO on the weather radar control unit (CON-4A/4B).
Switch to AUTO: Tilt setting for weather scans is automatic.
Switch to MAN: Tilt is controlled with the manual tilt control knob.

Pitch and roll information from the aircraft vertical gyros, tilt information from the manually set tilt control, azimuth angle information from the azimuth (scan) synchro transmitter, and elevation angle information from the elevation synchro transmitter, are processed by the stabilization microprocessor drive motor. The elevation drive motor repositions the antenna to maintain line-of-sight.

Also supplied by the R-T unit is the azimuth motor drive signal which drives the antenna through the oscillating 180 degrees of azimuth (scan).

NOTE: Manual TILT should be used when analyzing terain and when analyzing storm characteristics. selection of either manual or autotilt is done with selected control units. The RF signal (transmitted or received) is conveyed by a wave guide between the antenna and the transceiver. Energization of the antenna is 115VAC 400HZ throught the selected transceiver.

(4) Dual System Antennas

Weather Radar - Dual Redundant Motor Antenna Drive ** ON A/C NOT FOR ALL

To provide for dual system operation, the antenna contains redundant position synchro transmitters. Synchro transmitters B6 and B1 and associated with system 1; synchro transmitters B4 and B3 are associated with system 2. These redundant servo loops are interconnected through redundant antenna connectors (J3001, system 1) and (J3002, system 2) to the RDR-4B system. All circuitry commmon to a dual system is configured in such a way that either a Receiver-Transmitter unit, indicator, or synchro transmitter failure will not render the RDR-4B system inoperative.
A system tranfert switch on the CON-4B control panel applies power to the selected system and applies a switching voltage to a waveguide switch mounted on the R-T mounting base.

The waveguide switch transfert the antenna rf feed (waveguide) to the selected R-T unit. On the figure, sytem 1 is selected for operation by placing the System Transfert Switch (STS) on the CON-4B in the SYS 1 position. This energizes and initiates the switching necessary for system 1 operation.
For either dual or single system operation, motor B5 drives the antenna in azimuth movement and motor B2 drives the antenna in elevation position.

NOTE: The single system antenna is designed for use with one R-T unit. The function and components of the single system antenna are the same as the dual system antenna except that single synchros are used in lieu of redundant synchros and only on connector (J3001) is wired to electrical components in the antenna.

C. Weather Radar Antenna

Weather Radar - Antenna ** ON A/C NOT FOR ALL

The weather radar antenna is controlled in azimuth and elevation by the transceiver CPU. The decoded binary control data in the transceiver activates the antenna scan and elevation steeper motors through the corresponding power circuits. The indication of these positions is sent to the CPU for comparison. The RF signal (transmitted or received) is conveyed by a wave guide between the antenna and the transceiver. Energization of the antenna is 115VAC/400 Hz through the transceiver.

D. Weather Radar Control Unit
Part of the weather radar controls are grouped on the control unit (TILT control, system GAIN control, MODE selection control, MULTISCAN MAN/AUTO mode).
This data is digitized and monitored by a CPU to generate a control word which is sent to the transceiver through a control bus line.

E. Wave Guide
A wave guide assembly ensures the RF connection between the WR antenna drive and the WR transceiver mounting tray.
The wave guide assembly is made up of rigid and flexible parts which have a standard rectangular section (1 in. x 0.5 in.).
(1) Wave Guide
A wave guide assembly ensures the RF connection between the WR antenna drive and the WR transceiver mounting tray.
The wave guide assembly is made up of rigid and flexible parts which have a standard rectangular section (1 in. x 0.5 in.).
(2) Wave Guide Switch
The wave guide switch is integral with the mounting tray. It ensures switching of the RF signal from the antenna to the transceiver. Moreover control circuits recopy the wave guide switch position to avoid transmission on a closed wave guide.

** ON A/C NOT FOR ALL

7. Operation

A. Operation

(1) Weather radar modes
The weather radar system uses the principle of radio echoing. It works at a normal frequency of 9333 MHz. The peak power emitted is 120 W approx. The weather radar transceiver generates microwave energy in the form of electromagnetic pulses via an X-band wave guide to the antenna. When these pulses intercept an appropriate target, part of the energy is reflected to the weather radar antenna and then to the transceiver. For each case, the system uses a different mode of operation which allows to vary the scanning of the antenna, the timing of the pulses and the processing of the WXR returns and the PWS (if the function is activated). The electronic circuits of the transceiver measures the elapsed time between the transmission of the wave and the reception of the echo to determine the target distance (it takes around 12.36 s for the electromagnetic wave to travel out and back for each nautical mile of the target range).
The angular position of the target is detected by the angular position of the antenna in its azimuth scan. The quantity of energy reflected to the antenna is proportional to the target density and the different levels of atmospheric disturbances (see table 1 below) are shown on the displays by different colors.
The detection of the turbulence areas is based on the doppler phenomenon.

--------------------------------------------------------------------------

! LEVEL DETECTED ! PRECIPITATION RATE ! COLOR OF ECHOES !

!------------------------!-----------------------!-----------------------!

! Z1 < 20 dBz ! less than 1 mm/h ! black !

! 20 less than or equal ! from 1 to 4 mm/h ! green !

! to Z2 < 30 dBz ! ! !

! 30 less than or equal ! from 4 to 12 mm/h ! yellow !

! to Z3 < 40 dBz ! ! !

! 40 less than or equal ! 12 mm/h and above ! red !

! to Z4/Z5 < 50 dBz ! ! !

!------------------------!-----------------------!-----------------------!

! Turbulence ! 5 m/s ! magenta !

-------------------------------------------------------------------------!

Table 1: Color Correspondence Table

(2) Windshear Mode
In the WXR/PWS, the doppler mode determines the wind field ahead the aircraft.
By a mathematical treatment, the system determines the hazard factor (so-called "F factor") related to the danger of a windshear event.
A hazard factor which exceeds a value of 0.13 and within 5 NM ahead of the aircraft is considered as the presence of a dangerous event and a related windshear alert is generated. The display of windshear hazard consists of an icon of red and black bands superimposed on the radar returns. These events are dangerous during takeoff and landing maneuvers. The PWS mode is automatically activated below 2300 ft. on the radio altimeter and any one of the two qualifier inputs (QB and QC or QB and QD) is valid. These conditions enable the automatic windshear detection operation on the weather radar control unit even if the 1/OFF/2 switch is in the OFF position. The PWS/AUTO/OFF switch must be set to AUTO.
The windshear mode is transparent to the pilot until a windshear event is detected.
When a windshear event is detected, the system generates the appropriate annunciations (visual and aural) to the flight crew.
The WXR/PWS system generates a graphic symbol (icon) for the indication and display of the position of the windshear.
The windshear detection function can operate either with the WXR modes activated or deactivated.
When the radar is operating in the weather detection mode and the windshear is detected, no pilot intervention will be required.
When the radar is OFF and the windshear is detected, the radar operation changes automatically to WX+T mode (if the selected range is less than 60NM) or WX mode (if the selected range is more than 60NM) to display the weather and windshear icons.
The selected range does not change.
In the windshear mode, the TILT and GAIN are controlled automatically on the WXR/PWS for the scanning.
The TILT displayed on the NDs is always in accordance with the mode selected on the weather radar control panel.
When the weather radar transceiver fails, the amber message PRED W/S is displayed on the NDs associated with the amber messages:

NAV: PRED W/S DET FAULT on the upper ECAM DU
PRED W/S DET in the INOP SYS item of the STATUS page on the System Display (SD).

NOTE: The system has to reject echoes due to ground clutter or moving surface.

NOTE: In some cases, the pilot has to turn off the windshear mode (PWS/OFF/AUTO switch to OFF) for the following reasons:

When the aircraft is in a gate area or in a maintenance hangar to avoid radiation danger for persons
When nuisance aural alerts are generated.

NOTE: In order to ensure optimum performance for the predictive windshear function, the radome must be at least equal to class B category 1.

(3) Logic of scanning mode
The antenna scan pattern varies depending on the mode of operation.

(a) WXR scan pattern
In the WXR mode, the antenna performs a scan of 180° in azimuth and tilt (pitch) coverage of +/- 15°.
Stabilization limits are +/- 25° in the pitch axis and +/- 40° in the roll axis. The antenna scans the zone 15 times per minute with a beam opening of 3.6° in elevation and 3.5° in azimuth.
An antenna scanning is performed in 4 seconds with the transmission of 720 data words to the data bus lines.
When the two ranges selected on the EFIS control sections are identical, the radar images displayed on the NDs are refreshed for every 4 seconds.
On the contrary, when two different ranges are selected on the EFIS control sections, the images are refreshed for every 8 seconds.

(b) Weather and windshear scan pattern
When the system is placed in an alternate weather/windshear mode, the weather scan process is performed during the left-to-right scans and the windshear scan process is performed during the right-to-left scans. In this case, the antenna scans only an arc of +/- 60°.
The detected windshear targets are displayed only in the area +/- 30° from the aircraft centerline.
An antenna scanning is performed in 3 seconds and another 3 seconds are used to refresh data inside the CPU.
When the two ranges selected on the EFIS control sections are identical, the radar images displayed on the NDs are refreshed for every 6 seconds.
On the contrary, when two different ranges are selected on the EFIS control sections, the images are refreshed for every 12 seconds.

(c) Windshear scan pattern
The windshear scan is performed during the right-to-left scans and left-to-right scans.
The antenna scans only an arc of +/- minus 60°.
The detected windshear targets are displayed only in the area +/- 30° from the aircraft centerline.
When the two ranges selected on both EFIS control sections are identical, the radar images displayed on the NDs are refreshed for every 6 seconds.
On the contrary, when two different ranges are selected on the EFIS control sections, the images are refreshed for every 12 seconds.

NOTE: If the roll angle exceeds 28°, the windshear detection is no more active.

(4) Logic of scanning mode

WR/PWS - Logic of scanning mode ** ON A/C NOT FOR ALL

The antenna scan pattern varies depending on the mode of operation.

(a) Weather radar scan pattern
In weather radar mode, the antenna scans a 180 deg. in azimuth and has tilt (pitch) coverage of plus or minus 15 deg.
Stabilization limits are plus or minus 25 deg. in the pitch axis and plus or minus 40 deg. in the roll axis.
An antenna scanning is performed in 4 seconds, this causes the transmission of 760 data words at each antenna scanning.
The weather radar system features a 4-second constant refresh rate of the WX image whatever the ranges selected on the CAPT and F/O EFIS control sections of the FCU.

(b) Weather and windshear scan pattern, no detected windshear event
When the system is placed into alternate weather/windshear scan pattern and no windshear event is detected, the antenna scan pattern is as follows:

Clockwise weather scan with plus or minus 90 deg. of azimuth coverage and processing for weather
Counterclockwise windshear scan with full plus or minus 90 deg. of azimuth coverage, but with windshear processing limited to the plus or minus 45 deg. sector.
However, the WR/PWS have to update the refresh rate of the WX image to 12 seconds due to sharing of processing between windshear and radar.

(c) Weather and windshear scan pattern, with windshear event detected
When the system is placed into alternate weather/windshear scan pattern and the system detects a windshear event, the antenna scan pattern is as follows:

Clockwise weather scan, from minus 90 deg. to plus 90 deg.
Counterclockwise windshear scan, from plus 90 deg. to minus 45 deg., with windshear processing between plus 45 deg. and minus 45 deg.
The next clockwise scan is from minus 45 deg. to plus 45 deg. to validate windshear
The next counterclockwise scan is from plus 45 deg. to minus 90 deg. to validate windshear. No processing occurs between plus 45 deg. and minus 90 deg.
Clockwise WX scan, from minus 90 deg. to plus 90 deg.
The sequence is repeated as long as windshear event is detected. If a windshear event is not detected, the system reverts to the alternating weather/windshear scan pattern described above.
The refresh rate of the WX image is minimum 16 sesonds due to sharing processing between radar and windshear event detection.

(d) Windshear scan pattern
When the system operates in windshear mode only, the scan pattern is plus or minus 45 deg. azimuth coverage on both the clockwise and counterclockwise scans.
This mode occurs if the operator has placed the weather radar to OFF mode.
Windshear data are processed during both directions of antenna scanning.
In this case the windshear mode works transparent to the flight crew until a windshear event is detected.
The refresh rate of the display is 8 seconds.

(5) Radar multiscan mode
The multiscan mode manages the antenna beam tilts automatically. The antenna tilts are controlled for optimum weather detection during each phase of flight. This mode uses a low and high beam to examine short and long range, even while on the ground. Data for display is automatically selected from the upper beam, lower beam or both depending on the flight regime, clutter situation and optimum weather detection requirements.

NOTE: At each initial flight of the aircraft, the multiscan radar transceiver needs to be calibrated (each transceiver must be turned ON approximately for four minutes) during a short period in stable flight conditions. Before the initial calibration step, it is possible that the weather image shows an excessive ground clutter. If the initial calibration step is not performed or it is not completed, the multiscan radar transceiver will calibrate itself during the next flights.

(a) Cycle times
It is the total amount of time taken by the multiscan radar to scan for information during various modes of operation. It can vary between 6 and 12 seconds. The radar updates some portion of the weather, windshear (depending on the mode of operation) on every radar antenna scan. Therefore, a new data set is completed after every radar sweep. If you start from time zero, a complete new set of data is obtained from the radar at the end of each cycle.

NOTE: The display update rate (ref. Para. E.(4)(a)) is the actual information seen by the flight crew. The cycle time describes the function done by the multiscan in the background.

(b) Weather mode scan pattern
When the multiscan radar operates in the weather mode, only two radar scans are utilized. 4-second sweep is utilized for the high beam and 4-second sweep is utilized for the low beam. Therefore, the total cycle time is 8 seconds.

(c) Windshear mode scan pattern
The windshear mode is automatically activated below the altitude 2.300 ft. Above Ground Level (AGL). The time required for one radar sweep changes from 4 to 2.8 seconds due to the fact that the radar sweep changes from 180° to 120°. In the windshear mode, the first antenna scan (left to right) is utilized for the multiscan high beam. The second scan (right to left) is a windshear scan. The third scan (left to right) is utilized for the multiscan low beam. The fourth scan (right to left) is again a windshear scan. Thus, the total cycle time during the windshear mode is 11.2 seconds.

(6) Radar Multiscan mode
The Multiscan mode manages the antenna beam tilts automatically. The antenna tilts are controlled for optimum weather detection during each phase of flight. This mode uses a low and high beam to examine short and long range, even while on the ground. Data for display is automatically selected from the upper beam, lower beam or both depending on the flight regime, clutter situation and optimum weather detection requirements.

NOTE: At each initial flight of the Multiscan radar transceiver, the transceiver needs to be calibrated (each transceiver must be turned on for approximately four minutes) during a short period in stable flight conditions. Before the initial calibration step, it is possible that the weather image shows an excessive ground clutter. If the initial calibration step is not performed or is uncompleted, the Multiscan radar transceiver will calibrate itself during the next flights.

(a) Cycle times
Cycle time refers to the total amount of time that the Multiscan radar scans for information during various modes of operation of the radar. Total cycle time can vary between 6 and 12 seconds. The radar updates some portion of the weather, windshear (depending on the mode of operation) on every radar antenna scan. Therefore, a new data set is completed after every radar sweep. If you start from time zero, a completely new data set of information is obtained by the radar at the end of the one cycle.

NOTE: The display update rate (Ref. para. E.(4)(a)) is what the flight crew actually sees. Cycle time describes what Multiscan is doing in the background.

(b) Weather mode scan pattern

Weather Radar - Multisan Scan Pattern ** ON A/C NOT FOR ALL

When Multiscan operates in the weather mode only two radar scans are utilized. One four-second sweep is utilized for the high beam and one four-second sweep is utilized for the low beam. Therefore, the total cycle time is 8 seconds (Ref.Fig.010).

(c) Windshear mode scan patterm
The Windshear mode is automatically activated below 2.300 FT AGL. The time required for one radar sweep changes from 4 to 2.8 seconds due to the fact that the radar sweep changes from 180° to 120°. In windshear mode, the first antenna scan (left to right) is utilized for the Multiscan high beam. The second scan (right to left) is a windshear scan. The third scan (left to right) is utilized for Multiscan low beam. The fourth scan (right to left) is, again, a windshear scan. Thus, total cycle time during windshear mode is 11.2 seconds (Ref.Fig.010).

B. Pulse Duration and Range Timing

Weather Radar - Pulse Transmission Timing Diagram ** ON A/C NOT FOR ALL

This section provides the timing details for the transmitting and the processing of radar data.

(1) Epoch timing (non-windshear modes)
An epoch is the time interval in which a radial of radar data is processed. The time is equal to the size of the radar processing element in degrees divided by the antenna scan rate. The rate does not include any added dithering delays. The specifications for the range, element size, scan rate, and process epoch period are shown in table a.

-----------------------------------

! Range ! All ranges !

!----------------!----------------!

! Element size ! 0.375° !

!----------------!----------------!

! Scan Rate ! 45°/sec !

!----------------!----------------!

! Epoch ! 8.333 !

! Period ! +/- 5 µs !

-----------------------------------

Table a. Epoch Timing Table

(a) Transmitter pulse width values
The transmitter pulse widths are 6.0 and 20.0 µs. Accuracy of the pulse width is +/- 0.2 µs.

(b) Transmitter pulse pattern

Weather Radar - Windshear Transmit Pulse Pattern ** ON A/C NOT FOR ALL

The transmitter pulse pattern for all selected ranges are as follows: one 20 µs pulse and four 6 µs pulses will be transmitted during each epoch. The Pulse Repetition Frequency (PRF) for the 6 µs pulses is 1839Hz (543.83 µs).

Weather Radar - Pulse Transmission Timing Diagram ** ON A/C NOT FOR ALL

shows the non-windshear pulse pattern.

(2) Process epoch timing (windshear mode)
An epoch is the time interval in which a radial of radar data is processed. The process epoch timing is maintained by DSP1. The rate does not include any added dithering delays. The specifications for the element size, scan rate and process epoch period are shown in table b.

-----------------------------------

! Range ! All Ranges !

!----------------!----------------!

! Element Size ! 1° !

!----------------!----------------!

! Scan Rate ! 45°/sec !

!----------------!----------------!

! Epoch Period ! 22.975 µs !

-----------------------------------

Table b. Process Epoch Timing Table

(a) Transmitter pulse width
The transmitter pulse width is 2 µs for windshear mode.

(b) Transmitter pulse pattern
The pulse repetition frequency is 3000HZ (333.3333 µs) and a total of 64 pulses are transmitted per epoch.

(3) Range resolution/timing
The requirements for the range resolution and timing for the system are as follows:

(a) Windshear mode
The unit takes data samples out to a range of 5NM. Sixty-four samples are taken, the sample resolution is 150 meters +/- 6 meters. The receiver starts sampling 4.0 µs after the end of the transmit epoch.

(b) Non-windshear mode
The transceiver splits the radar return into two separate analog channels: in-phase (I) and quadrature (Q) channels. The transceiver simultaneously samples each channel by the number of times and data as shown in table c. The transceiver transmits the pulse by converting the radar return signal into digital format data. The receiver sampling starts at a time equivalent to a range of 0.5 NM after the end of the transmitter pulse.

------------------------------------------------------------------

! Pulse Width ! Sampled Range ! Number of Samples Taken !

!----------------!-------------------!---------------------------!

! 6 µs ! 41.424 NM ! 247 !

!----------------!-------------------!---------------------------!

! 20 µs ! 331.392 NM ! 504 !

------------------------------------------------------------------

Table c. Receiver Sample versus Range

The resolution of each individual sample is defined using the following equation:

Sample Length = [(range)/sample quantity]*K

Where:

range = sampled range

sample quantity = 512

K = 12.34 µs/NM (electromagnetic propagation constant)

The 512 range bins from the 40NM short range data set (6 µs transmit pulses) and the 512 range bins from the 320NM long range data set (20 µs transmit pulses) are interpolated/decimated to produce the final 256 data bin set suitable for the output at the selected range. The 256 range bins are then linearly expanded to fill the 512 ARINC 708A data bus range bins. The transceiver displays radar returns with a range accuracy of 5% or 1/2 NM whichever is larger.

(4) Receiver selectivity
Selectivity of the receiver filter bandwidth is controlled to match the current transmitter pulse length as shown in table d. The specified filter bandwidths listed are single-sided 3 dB bandwidths.

-----------------------------------------

! Pulse Width ! Filter !

!-------------------!-------------------!

! 2.0 µs ! 250 KHz !

!-------------------!-------------------!

! 6.0 µs ! 100 KHz !

!-------------------!-------------------!

! 20.0 µs ! 25 KHz !

-----------------------------------------

Table d. Receiver Selectivity versus Transmitter Pulse Width

(a) Display updates
Display updates occur at a minimum rate of two updates per 26.67 seconds, worst case with three problem cases selecting long range weather and windshear mode operating.

C. Controls and Indicating
The various system controls are grouped on the weather radar control unit and on the EFIS control sections of the FCU.
The radar image control on the NDs is achieved through the scale selector switches located on the CAPT and F/O EFIS control sections of the FCU.

(1) Weather radar control unit

Weather Radar - Control Unit ** ON A/C NOT FOR ALL

The face of the weather radar control unit includes the following controls:

(a) A mode selector switch, item 6, which enables the selection of the WX, WX+T, TURB or MAP function.

(b) A TILT selector switch, item 4, which enables the control of the antenna elevation.
The antenna position is shown in degrees (opposite to the notch on the switch):

either from 0 to 15° upwards (UP)
or from 0 to -15° downwards (DN).

(d) A SYS switch, item 7, with three stable positions 1/OFF/2, which enables the selection of transceiver 1 or 2 and the deactivation of the transceivers.

(e) A PWS/OFF/AUTO switch, item 5, which enables the selection of the windshear function.
The face of the control unit is provided with the integral lighting. The INTEG LT potentiometer enables the lighting adjustment. The potentiometer is located on panel 111VU, at the left aft section of the center pedestal 100VU.

(f) A GCS switch, item 3, which is activated in the multiscan AUTO mode (this is the default position). The GCS switch is never activated in the MAN mode.

(g) A MULTISCAN switch, item 2, which enables the selection between MAN and AUTO modes.

(2) EFIS control sections (on the FCU)

EFIS Control Sections and Lighting/Loudspeaker Control Panels ** ON A/C NOT FOR ALL

In this part, the controls related to the selection of WX and windshear modes are described.

(a) A mode selector switch, item 1, made up of a rotary switch enables the selection of the ROSE or ARC function for display of a WXR image on the CAPT and F/O NDs.
Windshear information is available in the ROSE and ARC modes.

(b) A scale selector switch, item 2, common to EFIS, Flight Management and Guidance System (FMGS) and radar systems, enables the selection of 10, 20, 40, 80, 160 or 320 operation ranges in NM for display of the WXR image on the CAPT and F/O NDs.
Windshear information is presented in the 10 NM minimum range and on other selected ranges. Moreover, yellow radial lines are displayed to indicate the windshear included location.

NOTE: In the ROSE or ARC mode, if the Captain or First Officer deactivates the FM data, the offside weather image will also be transferred on the ND. Only one scale selector switch can then control the WXR image display.

(3) Lighting/loudspeaker control panel
The CAPT and F/O lighting/loudspeaker control panels 301VU and 500VU which are connected to the CAPT and F/O NDs include the ND concentric potentiometers (item 3) for adjusting the brightness of the image displayed on the NDs. The outer knob of each potentiometer controls only the brightness of the radar image.

D. Utilization of Controls and Indicating

(1) Radar operation areas

Weather Radar - Radar Precaution Areas ** ON A/C NOT FOR ALL

Special precautions:
On the ground, on the weather radar control-unit, before you move the WXR/PWS control switch from position OFF to position 1 or 2 (in dual configuration) and select a DISPLAY mode different from OFF, make sure that, in an arc of +/- 135° degrees on the two sides of the aircraft centerline:

There are no persons and no large metal objects (for example a hangar) at less than 5 meters from the antenna that moves.
There is no fuel at less than 1.5 meters from the antenna that moves.
During maintenance, when you start the system test, make sure that there are no persons and no objects in the radome.

(2) Operation of the weather radar transceiver
The transceiver is always supplied in order to achieve maintenance function. On the weather radar control unit, after the selection of the WX function by the MODE selector switch, the SYS switch must be set to position 1 to operate the transceiver.

NOTE: No pre-heating time is necessary for the operation of the transceiver.

NOTE: When the aircraft is parked, the TEST mode on the Multipurpose Control & Display Unit (MCDU) must be preferably selected as a safety precaution.

On either EFIS control section of the FCU, the mode selector switch must be set to the ROSE or ARC position to obtain the image display on the corresponding ND.

NOTE: The transceiver is deactivated when the SYS switch on the control unit is set to the OFF position.

(3) Utilization of the weather radar control unit

Weather Radar - Control Unit ** ON A/C NOT FOR ALL

(4) Utilization of the weather radar control unit - mode selection (item 6)
The modes (WX, WX+T, TURB, MAP) are selected by placing the notch provided in the mode selector switch in front of the engraving of the modes.

WX
This mode corresponds to the normal operation in weather detection. It provides disturbances up to 320 NM.
The radar images are displayed on the NDs and are in four colors (black, green, yellow, red) and their intensity corresponds to the strength of the return signal.
WX+T
This mode corresponds to the operation in weather and turbulence detections.
All turbulent/non turbulent areas beyond 50 NM are displayed in the conventional black, green, yellow and red as in the WX.
TURB
This mode corresponds to the operation in turbulence detection.
Turbulence detection is limited to the first 50 NM regardless of the WXR range selected and displayed.
The turbulence area displayed on the NDs is in magenta.

NOTE: There is no detection of turbulence in clear sky.

MAP
This mode is only used for display of the ground map. A combination of transceiver gain, antenna position (TILT) and range selection enables the display of a larger area and the identification of major changes in the ground map (e.g, a sea cost, a lake, a mountain, an island, etc.)
The color display follows the color mentioned in the related table (see table 1 - Para. 7. A.).
If the image is too bright due to great reflection intensity, it can be dimmed by the GAIN potentiometer.

(5) Utilization of the weather radar control unit - system selection and start up: SYS switch (item 7)
This switch has three positions (1/OFF/2). It enables:

The selection and activation of transceiver 1 or 2 (if the second transceiver is installed)
The suppression of the radar image on the NDs, when the NDs are in the ROSE or ARC mode.

(6) Utilization of the weather radar control unit - GAIN control (item 1)
The GAIN control potentiometer enables the manual control of transceiver sensitivity in the WX, WX+T, TURB and MAP modes.
When the potentiometer is fully rotated clockwise, the MAX position provides maximum calibrated transceiver gain level (maximum receiver sensitivity). Counterclockwise rotation of the GAIN potentiometer decreases the gain towards the MIN position.
When the GAIN potentiometer is in the CAL position (no gain level), no indication appears in the lower right corner of the NDs.
When the GAIN potentiometer is in a position other than CAL, the MAN GAIN indication is displayed in white with EIS2 (MAN indication in green with EIS1).
In windshear mode, the gain control is automatic for WXR/PWS scanning.

(7) Utilization of the weather radar control unit - TILT control (item 4)
The TILT selector switch enables the variation of the antenna elevation angle in 1/4° steps on a non-linear scale graduated in degrees, within a range of +15° (UP) to -15° (DOWN) in relation to a horizontal plane defined by the stabilization system.
The TILT value selected on the weather radar control unit is displayed in cyan in the lower right corner of the ND in this form: MAN +/-XX.X°.
The antenna tilt fault is set:

If the elevation monitor detects a failure in the elevation drive.
If a red WXR ANT failure warning message is indicated in the lower right corner of the ND.

In windshear mode, the tilt is automatic for WXR/PWS scanning.
In windshear mode, the tilt indication on the NDs is replaced by the green PWS SCAN indication.

(8) Utilization of the weather radar control unit - PWS/OFF/AUTO switch (item 5)
When the PWS switch is in the AUTO position, the windshear detection is automatic if the altitude is lower than 2300 ft. and qualifiers A and B are valid. This automatic operation can be inhibited when the switch is in the OFF position.

(9) Utilization of the weather radar control unit - GCS switch (item 3)
The GCS function is activated in the multiscan AUTO mode. The GCS switch is spring-loaded to the AUTO position. Therefore, during normal operation, ground clutter is automatically removed from the display. If the display of ground clutter is required, the switch can be manually set to the OFF position at any time.
The GCS function is available in multiscan AUTO mode operation for the WX and WX+T modes. The GCS function is not active during MAP mode where terrain is being displayed. The GCS function is not available in the MAN mode of the multiscan operation.

(10) Utilization of the weather radar control unit - MULTISCAN switch (item 2)
The MULTISCAN switch is used to switch between MAN and AUTO modes. In the MAN position, all control operations are described in the MAN mode section. In the AUTO position, the system operates in the multiscan AUTO mode.

(11) Utilization of the weather radar control unit - TILT control value (item 3)
The TILT selector switches enable the variation of the antenna elevation angle in 1/4 deg. steps on a non-linear scale graduated in degrees, within a range of +15 deg. (UP) to -15 deg. (DOWN) in relation to a horizontal plane defined by the stabilization system.
This antenna elevation angle is displayed in cyan in the R lower corner of the ND and progresses in steps of 0.25 deg.
If the antenna position is different from the TILT selector switch position, a red ANT failure warning message replaces the TILT indication in the R lower corner of the ND. In windshear mode, the tilt is automatic and the tilt displayed on ND is always the selection on the radar control section although different in the antenna.
In the windshear position, the tilt control is automatic in the WR/PWS for the scanning. However, the tilt displayed on ND is in accordance with the one selected on the radar control unit.

(12) Utilization of the weather radar control unit - OFF/AUTO PWS switch (item 4)
In AUTO position, the windshear detection is automatic if altitude is lower than 2300 ft and qualifiers A and B are valid. This automatic operation can be inhibited when the switch is in the OFF position.

(13) Utilization of the weather radar control unit - MAN/AUTO TILT switch (item 6)
This mode is used to select between manual mode or autotilt mode.
In MAN position, all controls operate as described in the manual mode.
In AUTO position, the system operates in autotilt mode (automatic tilt and no action of the crew is necessary).

(14) Utilization of the EFIS control sections and lighting/loudspeaker control panels

EFIS Control Sections and Lighting/Loudspeaker Control Panels ** ON A/C NOT FOR ALL

(a) Mode selector switch (item 1)
This switch enables the image display on the corresponding ND whenever the ROSE or ARC mode is selected and the transceiver is supplied. In this case, the radar image is displayed in the background of the navigation image. If neither the ROSE or ARC mode is selected, the message W/S CHANGE MODE is shown on both NDs when there is a windshear alert. The pilot is advised to select the ARC or ROSE mode to see the W/S icon. The color depends on the W/S alert level.

(b) Scale selector switch (item 2)
This selector switch enables the display of the range selected for an optimum use of the radar image on the corresponding ND. For each of the following ranges: 10, 20, 40, 80, 160 and 320, four concentric range arcs are displayed respectively spaced 2.5, 5, 10, 20, 40 and 80 NM, when the mode selector switch is in the ARC position. Only 2 range arcs are displayed in the ROSE mode.
The windshear information is presented in the 10 NM range only. If a windshear alert is generated but the selected range is greater than 10 NM, the message W/S: SET RNG 10 NM is shown on the NDs. In this case, the pilot is advised to select the 10 NM range. The color depends on the W/S alert level.

(c) Radar image brightness control (item 3)
The ND potentiometer enables the adjustment of brightness and contrast of radar echoes in relation to the navigation image which is superimposed.
However, the adjustment range does not allow the total extinction of the image. The OFF position of the potentiometer corresponds to the minimum brightness and the BRT position corresponds to the maximum brightness.

NOTE: A photoelectric cell associated with each ND also adjusts the image brightness as a function of ambient light variations.

(15) Weather-radar data display on the NDs

In the figure, Details (A) and (B), the ROSE and ARC modes are shown on the ND for the radar image.
Messages give the crew information on the tilt and gain selected on the weather-radar control unit. Other messages show the failures that have an effect on the operation of the radar system. All these messages are shown in the lower right corner of each ND when you select the radar image.

NOTE: The tilt information and gain selection are shown on the NDs when there is the "NO FAILURE" warning message or when the TEST mode is not selected.

The different failures that can have an effect on the radar image are given in the decreasing order of importance. If more than one failure occurs, only the most important one is shown (ref. details (C) and (D) on the figure).
Two types of failures can have an effect on the radar system:

(a) Failures that cause the loss of the radar image.
These messages are shown in red:

- NO

WXR : shows an overheating of the DU

- WXR

R/T : shows a failure of the weather radar transceiver

- WXR

ANT : shows a failure of the weather radar antenna

- WXR

CTL : shows a failure of the weather radar control unit

- WXR

RNG : shows an error of comparison between the range

from the EFIS control section and the data copy received

on the DMC via the radar data bus.

(b) Failures that do not have an effect on the radar image.
These messages are shown in amber:

- WXR

WEAK : shows the loss of the transceiver calibration

- PRED

W/S : shows a failure of the windshear function

- WXR

ATT : shows an attitude failure from the ADIRU

- NO

AUTOTILT : shows a failure of the multiscan function

- WXR

STAB : shows the loss of the radar antenna stabilization

- WXR

TEST : shows the selection of the radar TEST mode.

(16) Weather radar data display on the NDs - operational message

Weather Radar - Data Displayed on the NDs ** ON A/C NOT FOR ALL

(operational message that does not affect the radar image)
The corresponding message is displayed in green instead of the TILT value:

- PWS : indicates that the weather radar operates in the windshear

SCAN mode only (weather radar SYS selector switch set to OFF and

PWS mode selector switch set to AUTO on the weather radar

control unit). On the ground, the qualifier logic has to be

satisfied.

(17) Windshear data display (refer to Table 2)

Windshear - Data Displayed on the NDs ** ON A/C NOT FOR ALL

(a) Windshear indications
An icon superimposed on the radar image shows the location of a windshear area to the crew.
This icon is made of alternating red and black arcs. For 10 NM range selection and above, yellow radial lines are shown at the edges and start beyond the windshear event. These lines are superimposed on the radar image and continue to the edge of the display area to give direction information about the windshear.
The windshear data is also shown when the SYS switch on the radar control unit is set to OFF and the PWS switch on the weather radar control unit is set to AUTO.

(b) Windshear alert

Windshear - Windshear Alert Ranges and Altitudes ** ON A/C NOT FOR ALL

Windshear - Windshear Alert Levels and Locations ** ON A/C NOT FOR ALL

1 Alert levels
There are three alert levels that are related to the event seriousness and to its distance from the aircraft. The Weather Radar (WXR) gives the crew visual and aural warnings which are in relation to the detected level.
Alerts are inhibited:

During takeoff, when the aircraft speed is 100 kts or more and the aircraft altitude is less than 50 ft Above Ground Level (AGL).

a Windshear warning alert (level 3)
This alert is for the most dangerous events.
It is given for windshear events detected in a range of +/- 0.25 NM from the longitudinal axis of the aircraft and in a range of +/- 30° in relation to the aircraft heading.
On the ground, the maximum range is 3 NM. In flight, the maximum range is 1.5 NM.
During the takeoff, when the aircraft speed is less than 100 kts, warnings and cautions are not inhibited. During the takeoff, when the aircraft speed is 100 kts or more and until the aircraft is 50 ft AGL, alerts are inhibited.
During takeoff, level-3 alerts are for ranges from 0 to 1.5 NM, and from 50 ft AGL to 1200 ft AGL. During the landing, this coverage includes ranges from 1.5 to 0.5 NM, and from 370 ft AGL to 50 ft AGL.
The range reduction is a linear function of the altitude. At the altitude of 370 ft AGL, the range is 1.5 NM, and at the altitude of 50 ft AGL the range is 0.5 NM.
Level 3 warnings are not inhibited when the aircraft speed is between 0 kts to 100 kts and at the altitude is from 50ft to 1200ft AGL.
The windshear warning alerts are given as follows:

An aural warning message: GO AROUND WINDSHEAR AHEAD in approach or WINDSHEAR AHEAD, WINDSHEAR AHEAD at takeoff, given by the radar synthesized voice
A visual warning: red W/S AHEAD message on the PFD.

On the PFD, level-3 alerts have display priority.
The weather radar transceiver must determine if the aircraft takes off or lands to give the applicable aural warning message "GO AROUND, WINDSHEAR AHEAD" or "WINDSHEAR AHEAD, WINDSHEAR AHEAD".
The GEAR UP discrete input controls the change between the GO AROUND, WINDSHEAR AHEAD aural warning message and WINDSHEAR AHEAD, WINDSHEAR AHEAD aural warning message.

b Windshear caution alert (level 2)
This level includes the events detected in a region from 0.5 to 3 NM, in a range of +/- 30° in relation to the aircraft heading but outside the windshear warning-alert region (level 3).
This caution alert is inhibited during landing, below 50 ft AGL.
Level 2 cautions are not inhibited when the aircraft speed is between 0 kts to 100 kts and at the altitude is from 50ft AGL to 1200ft AGL.
There should be no windshear caution alert (level 2) above 1200 ft.
The windshear caution alert is announced is given as follows:

An aural warning: MONITOR RADAR DISPLAY
A visual warning: amber W/S AHEAD message on the PFD.

c Windshear advisory alert (level 1)
This level is for events in a range of 5 NM from the aircraft, and +/- 30° in relation to the aircraft heading but outside the windshear warning and caution-alert regions (levels 2 and 3).
There should be no windshear advisory alert (level 1) above 1200 ft AGL.
No aural or visual alerts are given for this advisory alert, only the windshear icon is superimposed on the radar image.
The WXR transmits the windshear alerts in relation to their detection sequence. It is possible to transmit a maximum of eight events. Thus, alerts of different levels can occur at the same time.

-------------------------------------------------------------------------------

! ALERTS ! PFD ! ND ! AURAL WARNING !

!-------------!-----------------!-------------------!-------------------------!

! Advisory ! ! windshear icon ! !

!-------------!-----------------!-------------------!-------------------------!

! Caution ! W/S AHEAD ! windshear icon ! MONITOR !

! ! (AMBER) ! ! RADAR DISPLAY !

!-------------!-----------------!-------------------!-------------------------!

! Warning ! W/S AHEAD ! windshear icon ! during takeoff: !

! ! (RED) ! ! WINDSHEAR AHEAD !

! ! ! ! WINDSHEAR AHEAD !

! ! ! ! during landing: !

! ! ! ! GO AROUND !

! ! ! ! WINDSHEAR AHEAD !

-------------------------------------------------------------------------------

Table 2: Windshear Data Displayed

(18) Windshear warning display (Ref. table 3 below)

Messages Displayed on ND and Upper ECAM DU ** ON A/C NOT FOR ALL

(a) Windshear flags on NDs
When a windshear fault occurs, an amber PRED W/S message comes into view. The radar image remains available if this fault does not affect the radar modes or the detection function.
A detected fault is displayed when:

The aircraft is on the ground or the flap and slat control lever is in a position different from 0.
The PWS AUTO/OFF switch on the radar control unit is set to AUTO (the fault message is not displayed when the switch is set to OFF).

(b) Warning display on the upper ECAM DU
A detected windshear fault is indicated by the following amber messages:

NAV: PRED. W/S DET FAULT on EWD

PRED. W/S DET on SD INOP SYSTEM area.
This message is associated to the indications presented on the NDs.
When the PWS AUTO/OFF switch is set to OFF on the weather radar control unit, a green or amber PRED W/S OFF memo message is presented to the crew.
The color of this message depends on the flight phases.

-------------------------------------------------------------------------------

! ! UPPER ECAM DU ! ND ! AURAL WARNING !

!-------------!-----------------!-------------------!-------------------------!

! PWS ! NAV: ! PRED W/S ! Single chime !

! SYSTEM ! PRED. W/S DET ! (AMBER) ! !

! FAULT ! FAULT ! ! !

! ! (AMBER) ! ! !

!-------------!-----------------!-------------------!-------------------------!

! PWS ! PRED. W/S OFF ! ! !

! AUTO/OFF ! (GREEN or AMBER)! ! !

! SWITCH ON ! ! ! !

! CONTROL ! ! ! !

! UNIT IN ! ! ! !

! OFF ! ! ! !

! POSITION ! ! ! !

-------------------------------------------------------------------------------

Table 3: PWS INOPERATIVE - Warning Data Displayed

(19) Record in the Flight Data Interface Unit (FDIU)
The FDIU receives the following PWS data through the DMCs:

W/S caution alert (level 2)
W/S warning alert (level 3)
W/S AUTO/OFF
W/S internal fault
W/S external fault
DMCs/FWCs PWS pin program status.

This data, except the PWS PIN PROG status, is transmitted only from the DMCs if the DMCs/FWCs PWS PIN PROG is valid (grounded).

E. Reconfiguration Switching

Weather Radar - Control and Indicating ** ON A/C NOT FOR ALL

In normal configuration, the weather radar transceiver receives the altitude information from its corresponding ADIRU.
In case of ADIRU1 failure, the pilot can select the altitude information from ADIRU3.
This selection is through the AIR DATA selector switch installed on panel 8VU, on the center pedestal.

** ON A/C NOT FOR ALL

8. Test

A. BITE Description

(1) General
The BITE facilitates maintenance on in-service aircraft. It detects and identifies a failure related to the system.
The BITE of the WXR/PWS is situated in the radar transceiver and functions through two ARINC 429 low-speed buses (an input bus from the CFDIU and an output bus to the CFDIU).
The BITE:

Transmits permanently WXR system status and its identification message to the CFDIU
Memorizes the failures which occurred during the last 63 flight legs
Monitors data inputs from the various peripherals (EFIS control section, ADIRUs, RAs)
It transmits the result of the tests performed and self-tests to the CFDIU
Can communicate with the CFDIU through the MCDU menus
Acquires the general maintenance parameters (UTC, date, aircraft ident) and command codes from the CFDIU.

The PWS interface with the CFDIU is composed of:

An ARINC 429 low speed bus from the CFDIU.
The data sent by the CFDIU are:

---------------------------------------------------------

! LABEL ! PARAMETER ! FORMAT !

---------------------------------------------------------

! 125 ! UTC ! BCD !

! 155 ! AIRCRAFT CONFIGURATION 1 ! DISC !

! 156 ! AIRCRAFT CONFIGURATION 2 ! DISC !

! 227 ! COMMAND ! DISC !

! 260 ! DATE ! BCD !

! 301 ! AIRCRAFT IDENT ! ISO !

! 302 ! AIRCRAFT IDENT ! ISO !

! 303 ! AIRCRAFT IDENT ! ISO !

---------------------------------------------------------

An ARINC 429 low speed output bus to the CFDIU:
The data sent to the CFDIU are:

---------------------------------------------------------

! LABEL ! PARAMETER ! FORMAT !

---------------------------------------------------------

! 354 ! LRU IDENTIFICATION ! ISO !

! 356 ! FAULT MESSAGES ! ISO !

! 377 ! EQUIPMENT IDENTIFICATION ! BCD !

---------------------------------------------------------

The BITE can operate in two modes:

* Normal mode: It continuously reports the failures of all

classes depending on the maintenance flight phase

* Interactive mode: It provides an interactive dialog with

an operator using a MCDU.

NOTE: The WXR/PWS complies with specification ABD0048, Issue C.

(2) Normal mode
During the normal mode, the BITE monitors cyclically the status of the WXR/PWS. It transmits its information to the CFDIU during the concerned flight.
In case of fault detection, the BITE stores the information in the fault memories. These items of information are transmitted to the CFDIU by an ARINC 429 message with label 356.

(3) Interactive mode
The interactive mode can only be activated on the ground and through the line key adjacent to the RADAR 1 indication presented on the SYSTEM REPORT/TEST/NAV page of any of the MCDU.
This mode enables communication between the CFDIU and the BITE of the weather radar transceiver by means of the MCDU.

Weather Radar - Maintenance Test Procedure - Access to the RADAR Page ** ON A/C NOT FOR ALL

The interactive mode is composed of:

LAST LEG REPORT

Weather Radar - Maintenance Test Procedure - Sub-menus (Sheet 1) ** ON A/C NOT FOR ALL

This report contains the fault messages related to the external or internal failures (class 1 and 2) recorded during the last flight leg.
The following tables give the list of the failure messages which can be reported and indicate the failure class assigned to them as defined by the CFDIU standard.

-------------------------------------------------------------

! Reported Internal Failures !

!-----------------------------------------------------------!

! MESSAGE ! CLASS ! ATA !

-------------------------------------------------------------

! WXR1 (1SQ1) ! 1 ! 34-41-33 !

! WXR ANTENNA (11SQ) ! 1 ! 34-41-11 !

! WXR CTL PNL (3SQ)/WXR1 (1SQ1) ! 1 ! 34-41-12 !

! WXR MOUNTING TRAY (9SQ) ! 1 ! 34-41-37 !

-------------------------------------------------------------

! Reported External Failures !

!-----------------------------------------------------------!

! MESSAGE ! CLASS ! ATA !

-------------------------------------------------------------

! ADIRU1 (1FP1) ADR BUS/WXR1 (1SQ1) ! 3 ! 34-12-34 !

! ADIRU3 (1FP3) ADR BUS/WXR1 (1SQ1) ! 3 ! 34-12-34 !

! ADIRU1 (1FP1) IR BUS/WXR1 (1SQ1) ! 1 ! 34-12-34 !

! ADIRU3 (1FP3) IR BUS/WXR1 (1SQ1) ! 1 ! 34-12-34 !

! ADIRU1+3 (1FP1+3)/WXR1 (1SQ1) ! 1 ! 34-12-34 !

! QUALIFIER B1/2/WXR1 (1SQ1) ! 1 ! 79-33-11 !

! QUALIFIER C1/2/WXR1 (1SQ1) ! 1 ! 34-12-34 !

! QUALIFIER D1/2/WXR1 (1SQ1) ! 1 ! 34-12-34 !

! FCU (2CA) CP-L BUS/WXR1 (1SQ1) ! 1 ! 22-81-12 !

! FCU (2CA) CP-R BUS/WXR1 (1SQ1) ! 1 ! 22-81-12 !

! CFDIU (1TW)/WXR1 (1SQ1) ! 3 ! 31-32-34 !

! RA1 (2SA1)/WXR1 (1SQ1) ! 3 ! 34-42-33 !

! RA2 (2SA2)/WXR1 (1SQ1) ! 3 ! 34-42-33 !

! RA1 (2SA1)+RA2 (2SA2)/WXR1 (1SQ1) ! 1 ! 34-42-33 !

! GPWC (1WZ)/WXR1 (1SQ1) ! 1 ! 34-48-34 !

! POWER SUPPLY INTERRUPT ! 1 ! 24-00-00 !

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NOTE: Failure of one radio altimeter is a class 3 failure whereas it becomes a class 1 failure when two radio altimeters are faulty.

PREVIOUS LEGS REPORT
Weather Radar - Maintenance Test Procedure - Sub-menus (Sheet 1) ** ON A/C NOT FOR ALL
This report contains the fault messages related to the external or internal failures (class 1 and 2) recorded during the previous 63 flight legs.
LRU IDENTIFICATION
Weather Radar - Maintenance Test Procedure - Sub-menus (Sheet 1) ** ON A/C NOT FOR ALL
Allows to display the P/N, the S/N and the SW/N of the equipment.
GND SCANNING
Weather Radar - Maintenance Test Procedure - Sub-menus (Sheet 2) ** ON A/C NOT FOR ALL
It provides the failure information according to the monitoring and fault analysis during flight.
The WXR/PWS peripheral monitoring and internal cycle tests are used to detect transient failures.
By pressing the line key adjacent to the failure message, the operator is allowed to the corresponding Trouble Shooting Data (TSD). The peripheral monitoring and WXR/PWS internal cyclic tests are used to detect transient failures.
TROUBLE SHOOTING DATA (TSD)
Weather Radar - Maintenance Test Procedure - Sub-menus (Sheet 2) ** ON A/C NOT FOR ALL
Provides correlation parameters and snapshot data concerning the failure displayed in the LAST LEG REPORT and PREVIOUS LEGS REPORT.
CLASS 3 FAULTS
Weather Radar - Maintenance Test Procedure - Sub-menus (Sheet 3) ** ON A/C NOT FOR ALL
Allows to display the class 3 faults recorded during the last flight leg.
GROUND REPORT
Weather Radar - Maintenance Test Procedure - Sub-menus (Sheet 3) ** ON A/C NOT FOR ALL
Allows to present the class 1, 2 or 3 internal failures detected on ground.
These failures are different from those displayed on the LAST LEG REPORT and CLASS 3 FAULTS.
By pressing the line key adjacent to the failure message, the operator is allowed to access the corresponding TSD.
TEST
Weather Radar - Maintenance Test Procedure - Sub-menus (Sheet 4) ** ON A/C NOT FOR ALL
Weather Radar - Maintenance Test Procedure - Sub-menus (Sheet 5) ** ON A/C NOT FOR ALL
Weather Radar - Maintenance Test Procedure - Sub-menus (Sheet 6) ** ON A/C NOT FOR ALL
Allows a check of the correct operation of the WXR/PWS on ground.
This test can be performed by:
Either selecting the test function on the Liquid Crystal Display (LCD) of the weather radar transceiver
Or through the CFDS by selecting the test function on the RADAR 1 main menu page of the MCDU.
At the end of the BITE TEST, the test pattern comes into view.
Weather Radar - Test Pattern ** ON A/C NOT FOR ALL

NOTE: If a failure of the windshear system is detected during the BITE TEST, the windshear flags come into view.
If the failure does not affect the radar mode, the test pattern stays available.
If the failure affects the radar mode, nothing is shown.

All the information displayed on the MCDU during the BITE TEST configuration can be printed by the printer (Ref. AMM D/O 31-35-00-00).

[Rev.10 from 2021] 2026.04.02 06:23:20 UTC