Windshear - Windshear Alert Levels and Locations
Figure 016A
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-during landing, below 50 ft AGL.
There should be no windshear caution alert (level 2) above
1200 ft.
The windshear caution alert is announced by:
-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 covers the events located within 5 NM from the aircraft, within +/- 30 deg. of 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 1500 ft. No aural or visual warnings are provided for this advisory alert: only the windshear icon is superimposed on the radar image. The weather radar transmits the windshear alerts following their detection order. A maximum of 8 events can be transmitted. Therefore, alerts of different levels can be generated simultaneously.
-------------------------------------------------------------------------------| 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
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R **ON A/C 303-399, 401-499,
(5) Windshear data displayed (Ref. table 2 below) (if the predictive windshear function is activated) (Ref. Fig. 014A)
(a)
Windshear indications The location of a windshear phenomenon is indicated to the crew by means of an icon superimposed on the radar image. This icon consists of alternating red and black arcs. For 10 NM range selection and above, yellow radial lines appear at the edges and start beyond the windshear event. These lines, superimposed on the radar image, continue to the edge of the display area to provide directional information for the event. The windshear data are always displayed even if the system selector switch on the radar control unit is set to OFF. The windshear switch on the radar control unit has to be set to AUTO. When on the radar control unit, the weather radar system selector switch is set to OFF and the windshear mode selector switch is set to AUTO, the green "PWS SCAN" indication is displayed on the bottom right-hand corner of the NDs instead of the tilt indication to inform the crew that the weather radar operates in windshear mode only.
(b)
Windshear alert (Ref. Fig. 015, 016A)
1_ Alert levels
There are three alert levels defined in function of event
seriousness and distance from the aircraft. The weather radar
provides the crew with visual and aural warnings which vary in
function of the level detected.
a Windshear warning alert (level 3)
_ This alert corresponds to the most dangerous phenomenons. It is generated for windshear events detected within +/-
0.25 NM from the longitudinal axis of the aircraft and
within +/- 30 deg. scan of the aircraft heading.
On the ground, the maximum range is 3 NM. In flight, the
maximum range is reduced to 1.5 NM.
During takeoff, level 3 covers ranges from 0 to 1.5 NM,
from 50 to 1200 ft Above Ground Level (AGL). During
landing, this coverage is from 1.5 to 0.5 NM, from 370 to
50 ft.
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b
_
c
_
Range reduction is a linear function of altitude: at 370
ft, range is equal to 1.5 NM and reaches 0.5 NM at 50 ft.
During takeoff, this warning is inhibited from the time the
aircraft attains 100 kts and until it reaches 50 ft AGL.
Level 3 warning is inhibited below 50 ft (in approach
phase) and above 1200 ft.
The windshear warning alert is announced by:
-an aural warning message: GO AROUND WINDSHEAR AHEAD in approach or WINDSHEAR AHEAD, WINDSHEAR AHEAD at takeoff, generated by the radar synthesized voice. 中國航空網 m.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：A320飛機維護手冊 AMM NAVIGATION 導航3(45)
