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machten
27th Oct 2006, 16:52
Can anyone explain what Predictive Windshear Alerting is and how does it work. I've only heard of windshear warning through EGPWS. Is this something based on radar/lidar? Couldn't find anything through the search function.

FullWings
27th Oct 2006, 19:59
As I understand it, the predictive bit of the EGPWS uses Doppler returns from the normal weather radar to pick up any strong vertical motion ahead. It can only do this if there are some radar-reflective particulates in the air in question, like rain, dust, etc.

On the fit I fly with, you get things like: "Monitor Radar Display!" and "Windshear Ahead!" and it draws a pretty picture on the NAV display showing where it has detected the shear. Clever stuff.

I think the 'reactive' windshear detection is part of the GPWS and is based on change of wind component... "Windshear! Windshear!"

FlapsOne
27th Oct 2006, 20:58
Predictive windshear is a function of radar, not EGPWS.
Reactive windshear is an EGPWS function.

FullWings
28th Oct 2006, 09:31
Predictive windshear is a function of radar, not EGPWS.
You're right that you need radar for it to work. I'm not sure as to whether it lives in the same box as the EGPWS: these things tend to get lumped together in manuals for brevity...
Reactive windshear is an EGPWS function.
I think you might find that this feature existed in some GPWS units before EGPWS came on the scene, as you don't need position data (which many of the EGPWS features require) for reactive WS protection.

TolTol
28th Oct 2006, 11:58
Boeing 737NG manuals say that predictive windshear is produced by weather radar, reactive windshear is produced by the EGPWS (or GPWS with no forward looking terrain feature).

JackOffallTrades
30th Oct 2006, 01:10
Are any Airbuses fitted with predictive windshear? I've only seen it on a Boeing.