What if you can depart within 7 minutes?

Those rules of thumb apply to 121 more than 135/91 at smaller class D & G airports. As a previous poster stated Type I often has 5-20 minute hold over times, that is more than enough time to depart from the airports business jets operate from. When I did charter, I would typically de-ice (Type I) about 5-10 times a year and anti-ice (Type IV) twice.

Five minutes is “more than enough time”? Do you realize your HOT starts at the beginning of fluid application? Unless you’re deicing a 172 from a cherry picker on the runway it ain’t happening. And at TEB, forget about it.

Geez, people, if you can’t stand in front of the boss and be proud of your decision to spend some of his money to keep him (and more importantly, you) safe then seek employment elsewhere.

There are a ton of variables, and the advantage to being on this side of the fence is that you can make a logical decision, vs flying for an airline and having to do everything by the book. There are advantages to both.

WWYD if the ATIS is reporting freezing rain, its 0*, and nothing is sticking to the airplane cause its nice and warm cause you just pulled it out of the hangar? Coat the airplane in $10k worth of de-ice fluid, or fire her up and go?

Freezing rain? Jet in a heated hangar? 0F?

You get a splash of Type I since you'll get some precip on the airplane after pulling out, and Type 4 because you're in freezing rain.

But since you were in a hangar, you won't need dozens if not hundreds of gallons of Type I to get contamination off the airframe prior to applying Type IV.

At my previous job, at home base in a similar circumstances, we would spray Type IV on wings/tail in the heated hangar, load up in the hangar, pull out, fire up and go. Total time from exiting the hangar to wheels-up, maybe 5-6 minutes.

No contamination on the airframe in a heated hangar so no need for Type I...and spraying the Type IV yourself, you could ensure complete coverage on critical surfaces without totally wasting fluid and/or creating a GIGANTIC mess.

Different ways to SAFELY skin this cat...but if the jet is outside covered in frozen stuff, you're gonna need a lot of Type I to get it off regardless.

You can flame me if you want, but this type of thinking is why the Corporate accident rate is as high as it is.

Oh yeah? What is the last corporate jet to crash due to ground icing that was flown by a professional crew?

Challenger Montrose with Dick Ebersol?

So 14 years ago, and it was an airplane very sensitive to freezing precip. Quite the high accident rate.

I’ve been on both sides of the fence multiple times. After I first worked for a company that had an FAA approved ground icing program and went back to 91 to run a flight department I always asked myself...if it was a good idea then, why wouldn’t it be a good idea now? If the only variable was money I spent that stuff like it was growing on the trees.

And to answer your question...if it’s freezing rain I’m spraying the Type IV even if the airplane is steaming or I’m canceling the trip. Up to the boss. Since I don’t have a chart for calculating the thermal retention of aluminum I have no idea how long I have before the freezing rain starts to stick. A good friend once told me, “don’t write the first line of the accident report.” You wanted logic, that’s as logical as it gets in my opinion.