Hey everyone,

I read something that stood out to me in this months AOPA. Obviously if other means are available to remove frost, then by all means use them. But in a pinch, this will work. Been there and done it. So I was interested in what info/insight some of your more sage members have on this topic. Here is the paragraph from the airticle. It's the "illegal" part that caught my eye.

You can safely take off with frost on the wings, as long as it’s polished to a smooth surface.

Myth. You should only take off with wings and other lifting surfaces completely free of frost. Though perhaps little known, since 1960 the FAA allowed airplanes operated under FAR parts 135 and 125—and certain airplanes operated under FAR Part 91—to take off with frost accumulations that were polished. This could be done via several means. A large swatch of burlap can take the fuzz off of frost, as can a credit card, or even a rope slid along the wing. Makeshift, yes, but it works.

But as of August 2008, the FAA changed its mind about polished ice, and now it’s illegal. The reasoning behind the decision is in a May 8 Notice of Proposed Rulemaking (docket number FAA-2007-29281; Notice No. 08-06). The NPRM cites 11 known accidents in which individuals attempted to polish frost smooth, yet crashed shortly after takeoff. From now on, it’s clean wings and tails for takeoff, period.

NASA Glenn researchers say that it’s leading-edge roughness that dominates frost effects on lift degradation, while roughness on the rest of the wing causes drag increases. Losses in lift can be as high as 30 percent, and 40-percent drag increases can occur at the same time. NASA Glenn also quotes Cessna Aircraft Company as saying its Caravans can experience a 35-percent increase in stall speed with 0.1 inch of frost accumulation.

Never have had a problem with "frost" degrading performance, but I was always pretty fussy about cleaning wings and using wing covers. Wonder if those guys involved in the "frost" accidents were just lazy and didn't do a good job of sweeping, or else flew into freezing mist/drizzle and accumulated a load of nasty in a big hurry.

Gump

I took off one time with only the smallest amount of frost on my Cessna 180 wings, thought no big deal, sun will melt it in an hour.
Well I barely cleared the trees and mushed out completely when I pulled back on yoke. I was alone and light, had I had passengers I think i would have been a burnt spot in the trees. Never ever will I make that stupid mistake again

I believe several of those accidents referred to in the article involved Cessna Caravans. The Caravan recently underwent a special airworthiness review for icing certification, and passed, but special training of crews is now required.

But the accidents cited in that NTSB document were ones where pilots didn't get ALL the ice off the surfaces prior to departure. This is harder to accomplish and verify if the surfaces are really high above your head, and you don't have a big ladder and good light to verify.

An easy mistake to make, but even a little bit of ice on most modern aircraft wings can precipitate a deeply moving religious experience, as Woody notes.

There are all sorts of stories from the olden days of Alaska, of pilots roping the wings down to smooth off frost. And that was fairly common practice back then. But consider the types and design of the wings of most of those airplanes. Most "modern" aircraft today have somewhat more critical wing designs, at least the ones that are carrying a lot of passengers. Leave a little frost on a Cub wing (or a Standard) and it might not be too big a deal. But leave that same percentage of frost on a newer Cessna wing.....who knows?

I think the article hits the nail right on the head. Get ALL the frost and ice off the wings before you go flying.

MTV

I took off in a 660 Thrush with several inches of snow all over it , but I did have several thousand more feet of runway than necessary and the hopper was empty so I was 5 or six thousand lbs. lighter than normal. Most all of it blew off on the T/O roll. I couldn't tell any difference at all.
I did it because the FBO told me I HAD to be de-iced and it cost $200 to move the truck 50 ft. and the fluid was $40 a gl.
I'm not saying do that of course, I ws just surprised that I couldn't tell any difference is all. We use the NACA 4412 airfoil which is supposed to be very tolerant of damage and things like ice.

The guy next to me in the tiedown area asked "how much frost can you have on your wings and still fly" I said I didn't know, I didn't want to be the guy to find out. He fired up his C-170 and drove it right off the end of the runway at Merrill Field into the mobile home park.