POSITION  DIRECTION  RADAR SCAN  PAINT SWEEP  ANGLE (DEGREES)  TIME (SECONDS) 
SWEEP 1  L-R  BOTH WXR DATA UPDATED  BOTH WXR WITH ICON PAINTED  -90 TO +90  4 
SWEEP 2  R-L  UPDATED BOTH PWS DATA  BOTH PWS ICONS PAINTED  +90 TO -90  4 
SWEEP 3  L-R  BOTH WXR DATA UPDATED  ICON PAINTED BOTH WXR WITH  +90 TO -90  4 
SWEEP 4  R-L  BOTH PWS DATA UPDATED  BOTH PWS ICONS PAINTED  +90 TO -90  4 

WXR AND PWS SCAN PATTERN - APPROACH

COLLECTION = |45`
Antenna Scan During Weather and Windshear Operation Figure 8 (Sheet 2)
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POSITION  DIRECTION  RADAR SWEEP  PAINT SWEEP  (DEGREES) ANGLE  (SECONDS) TIME 
SWEEP 1  L-R  BOTH PWS DATA UPDATED  NONE  +60 TO -60  2 
SWEEP 2  R-L  BOTH PWS DATA UPDATED  NONE  +60 TO -60  2 
SWEEP 3  L-R  BOTH PWS DATA UPDATED  NONE  +60 TO -60  2 
SWEEP 4  R-L  UPDATED BOTH PWS DATA  NONE  +60 TO -60  2 

PWS ONLY SCAN PATTERN

Antenna Scan During Weather and Windshear Operation
Figure 8 (Sheet 3)

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 3)  A PWS caution is not generated if a PWS warning condition already exists.
 4)  The master caution and warning lights may be cancelled by pushing the lights to off.
 5)  The caution and warning messages from the WXR R/T are sent to the EFIS interface units where they are sent to the various display and aural flight deck units as shown on Figure 9.
Alert Prioritization
 1)  The PWS caution and warning aural alerts shown in Fig. 10 are prioritized by the enhanced ground proximity warning system (Enhanced GPWS) (AMM 34-46-00). This prioritization is used to prevent conflicting or simultaneous voice and visual alerting cues to the flight crew. The PWS inhibits the generation of PWS aural alerts when another aural alert is determined to be a higher priority.
 2)  The WXR R/T sends the Enhanced GPWS a PWS caution and a PWS warning status discrete along with the PWS aural alert on the hazard bus.
 3)  The WXR data bus 1 and 2 outputs from the WXR R/Ts are sent through the four terrain display relays shown on Fig. 4. These WXR data busses are disconnected when the GPWS has data that is of a higher prioriy than the PWS information on the WXR data busses.
 4)  A PWS discrete inhibit output from the WXR R/T to the traffic collision avoidance system (TCAS) is used to downgrade all resolution advisories (RAs) displayed on the PFDs and traffic advisories (TAs) displayed on the NDs and inhibits all aural alerts from the TCAS system. For more information about the TCAS system refer to AMM 34-45-00.
 5)  Right and left data busses 1 and 2 are sent from the right and left R/Ts normally through the unenergized contacts of the four terrain display relays. These output data busses are sent to the captain's and first officer's ND and the auxiliary EICAS display unit.
 6)  When the Enhanced GPWS determines that a higher priority alert than the PWS alert is present, the terrain relays are switched and the weather radar data is removed from the NDs and auxiliary EICAS display.
 7) The EFIS control panel has a terrain (TERR) switch to toggle between the GPWS terrain data and the WXR data bus information. a) When the WXR data is being displayed, pushing the TERR switch will remove the WXR data and display the terrain data. b) When the terrain data is displayed, pushing the TERR switch then the WXR switch on the EFIS control panel will again display the WXR data.
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