737ng Pws
 

G'day All,

Question regarding 737NG predictive windshear system.
Scenario....Aircraft parked at the gate....IRS aligned....engines shut down....WXR on both EFIS control panels NOT selected.
1 thrust lever is advanced until config horn is heard.
Will this allow the radar to begin to scan ?

Weather radar automatically begins scanning for ws when thrust levers are set for takeoff even with engine off or IRS not aligned.
I think the TL position for take-off config warning is less than take-off thrust , so it may not start if you stop there, but if you go to take-off thrust position it will start scanning.

but will it begin to scan even when the WXR is not selected?
the manual states that the pws is activated by pressing the WXR switch on the EFIS panel and will begin the scan 12 seconds after the application of takeoff thrust.....

Short answer - YES.
Once either thrust lever is advanced beyond 53 degrees the PWS will be activated. However if you only advance 1 at a time, the PWS will only be ON momentarily and thus not creating a safety hazard for ground personnel.