Originally Posted by
viper548
Not sure what you're looking for here but type 1 has to be applied before type 4.
Only if the airframe is contaminated, or your deice program requires it.
You won't see it in the airline world, but it is completely acceptable to spray a clean aircraft in a hanger with Type IV before pulling out into active precip.
A number of part 91 operators have procedures in place for this process, which is not prohibited by FAA or by deice fluid manufacturers and in no way whatsoever compromises the safety of flight.