A320 windshear sys

[captmilo]

hello !! In the a320 to get predictive windshear , one of the requirement is to have the atc on , so why is the atc needed to b on for predictive winshear to activate ????' ( for ref: fcom vol 1 ch -navigation ws sys part )

[TyroPicard]

So that the PWS switch only activates the wx radar transmissions when there is a reasonable chance that the a/c is taxying for T/O, and not just having an engine run?

[captmilo]

thnx . so basically the atc helps the wx radar o know dat shes taking off right ?? nd cud plz tell me where i cud find this written info ?? thank you
milo

[TyroPicard]

Nothing clever like that - merely my deduction. Four conditions for PWS to be on:
1. a/c below 2300 ft agl
2. PWS switch in AUTO
3. Either engine is running.

Now this might be the case on an engine run by a ground engineer - which would mean that the radar is transmitting even though the switch is OFF. This is undesirable.
So another condition - ATC on - is included. This implies there are pilots in the cockpit taxying out for take-off. Make sense?

[captmilo]

Hell Yeah , Also Did Some Research On It , Absolutely Does , Been Bugging Me For Days .... Thanks
Cheeers
Happy Lndigs

[aristoclis]

@Typicocard corr:TyroPicard

Why would the PWS switch be in auto position in the case on an engine run by a ground engineer? Shouldn't it be at off position, like the ATC switch?

[TyroPicard]

@Typicocard

Who?
TyroPicard wrote

Now this might be the case

Yes of course they should both be off. But how many times have you found a switch or pb in the wrong position after a hangar visit? Or after the previous crew got off? This is merely supposition on my part - a requirement to have two "we are going flying" switches on makes unwanted radiation effects less likely.

[aristoclis]

That's what happens with late night posts!

Although what you say makes sense, if I remember well WX radar (not PWS) operates on ground with switch on without other precondition (engine running). Suppose you (or engineer) forget this switch at on, many guys would be "illuminated" as well, wouldn't they? Why no extra protection here then?

[TyroPicard]

A very good question, and one that I am unable to answer....

[ALK A343]

Maybe because there is no cockpit indication of the predictive windshear being in auto, whereas with the weather radar you would get the tilt info and some kind of return on the ND. With the predictive windshear the only indication I recall is the amber ECAM MEMO when it is switched OFF during taxi. Off course this is only speculation on my part, there is nothing in the books.