*
Yellow shows medium weather
*
Red shows heavy weather
* Magenta shows turbulence.
The WXR system detects and shows turbulence only to 40 NM.
WXR System Messages
The ND shows WXR system messages on three lines. Line 1 shows WXR mode messages. These are the messages that show on line 1:
*
WXR (weather precipitation mode)
*
TURB (turbulence mode)
*
WX+T (weather and turbulence mode)
*
MAP (manual gain)
*
TEST (test mode).
Line 2 shows the antenna tilt value set on the WXR panel. The tilt value is +15 degrees to -15 degrees.
Line 3 shows the manual gain selection made on the WXR panel. The message for manual gain selection is CAL.
When the flight crew does not make a manual gain selection, the WXR RT uses preset calibrated gain and no gain message shows.
All WXR system messages show in the color cyan.
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WXR SYSTEM -NORMAL DISPLAYS
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WXR SYSTEM -PREDICTIVE WINDSHEAR
General Description
Weather radar with predictive windshear (PWS) detects windshear ahead of the airplane. PWS uses doppler radar returns, inertial data and air data to detect windshear. If PWS detects a windshear condition, it alerts the flight crew with visual and aural annunciations.
System On/Off -Takeoff
PWS turns on automatically when the airplane is on the ground and one of these conditions exists:
*
An engine gets to takeoff thrust
*
The flight crews pushes the WXR button on an EFIS control panel or control display unit (CDU).
The WXR button on the EFIS CP does not turn off the PWS if the engines are at takeoff thrust. PWS turns off automatically when the airplane climbs above 2300 feet radio altitude.
System On/Off -Approach
PWS turns on automatically when the airplane descends below 2300 feet radio altitude. PWS turns off automatically when one of these conditions exists:
*
Airspeed is less than 60 knots
*
The airplane climbs above 2300 feet radio altitude.
If PWS is on and WXR is not selected on the EFIS CP or the CDU, all antenna sweeps search for windshear. If WXR is selected, the antenna uses one sweep to search for windshear and the other sweep to search for normal weather returns. PWS operation does not affect the WXR mode or range selected by the flight crew.
PWS Display
If PWS detects windshear, it makes a windshear symbol on the ND. The symbol is red and black bars. Yellow bars go from the edges of the symbol to the compass rose. The yellow bars help the crew to see the PWS symbol.
The ND mode selector must be in a correct mode for the windshear data to show. These are the ND modes that show windshear data:
*
Expanded APP
*
Expanded VOR
*
Expanded MAP
*
Centered MAP.
Windshear data does not show above 1200 feet radio altitude.
PWS Automatic Display Function
If PWS detects a windshear threat, weather data automatically shows on both NDs. Weather data automatically shows if these conditions exist:
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WXR SYSTEM -PREDICTIVE WINDSHEAR
*
PWS detects a windshear threat
*
Airplane altitude is less than 1200 feet
*
WXR is not selected on either EFIS CP or CDU
*
The ND mode selector is in a correct mode.
PWS Fail
These EICAS messages show for a PWS failure:
*
Status message -WINDSHEAR PRED
*
Advisory message -WINDSHEAR SYS.
There are no ND messages for a PWS failure.
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WXR SYSTEM -PREDICTIVE WINDSHEAR ALERTS
General Description
If PWS detects a windshear threat, it makes an alert. The alert may be a warning or a caution. The alert the crew receives depends upon these conditions:
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