Predictive/Reactive Windshear (Airbus)

[steamd]

Hi Folks,
Could someone please explain to me in a nut shell, what is the difference between Predictive and Reactive windshear on the airbus??? Totally confused
Cheers :confused:

[Back Seat Driver]

The Predictive Windshear (PWS) function: (Surveillance system. ie WXR)
Detects windshears:
At least 10 s before a possible encounter
Between 0.5 nm and 5 nm in front of the aircraft
Triggers alerts.
The PWS function can detect and display up to 8 different windshears simultaneously.
The PWS function is available, if the PRED W/S button is set to AUTO, and:
If the WXR is operative, or at takeoff, if the WXR is OFF
In flight, if the aircraft is below 1 500 ft AGL.

REACTIVE WINDSHEAR DETECTION
A windshear alert triggers, when the aircraft encounters wind gradients during takeoff and landing, which could reduce the margin towards stall.
The windshear alert consists of:
A red windshear message displayed on both PFD.
It flashes during 9 s, then remains steady, as long as the windshear is detected.
An aural WINDSHEAR alert
Windshear
The reactive windshear detection is performed by the PRIMs

[steamd]

Your a champ.
Thankyou for the quick response. Prims?? or FACs:)

[Clandestino]

FACs on 320 family, PRIMs on 330/340. Not sure about the rest of the Airbi.

Predictive windshear works by comparing doppler shifts of radar returns so it will detect windshear only when there's liquid precipitation involved. However as strongest windshears are associated with areas of severe rainfall (or virga), it is quite useful.

[Graybeard]

Good description, Clandestino.

Forward Looking Windshear Detection is more descriptive than Predictive, as it detects what's there now, and not in the future. Yeh, I know, it predicts what you'll encounter soon.

Not only rainfall and virga, a good forward looking windshar weather radar will detect the blowing dust in Babylon.

GB

[Microburst2002]

Predictive windshear is, as the word implies, a prediction of windshear ahead. You will avoid it, if possible. If not, as below.

Reactive windshear is a detection of an actual windshear condition. You will call out "WINDSHEAR TOGA", advance thrust levers to TOGA and follow SRS orders, preferably wings level, without changing configuration until out of the WS. With AP ON, you can keep it on, but keep in mind it will disconnect if you reach angle of attack protection and alpha floor activates. You may need full aft sidestick.
Then, if height was near zero and you finally manage to start climbing, the call out is "pheeew"