BTD wrote: ↑Sun Mar 03, 2024 4:11 pm It will definitely run off. Not instantly, but over a couple of mins the coverage won’t be sufficient on flaps and slats if precip is falling. I’ve had to go back to spray because the wind blew off the type 4 well before the high time limit.

Thats why you leave the flaps/slats up until just before takeoff.

I believe most type 4 fluids have a shear value of 85kts. I guess gravity would affect these numbers and certainly precip, but the precip is covered by HOT tables. If in doubt, spray again.

There's a whole set of type 4 HOT charts for flaps extended. The times are lower than flaps up. Operational simplicity can be great if the lower holdover time is still sufficient.
Modifying SOP is above my pay grade. I do what I'm told and follow the correct HOT charts.