Flying with frost on the plane

birdus

birdus

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Jay Williams
Does anyone here have any friends who have flown with frost on the plane? I'm just wondering how significant an effect it actually has on how the plane flies. For example, if a Luscombe owner (other than me) were to fly with frost on the plane, would it stall at, say, 55 instead of 48? Would the aforementioned Luscombe owner (not me) even notice a difference?
 
Ok. Well.

One, I live in Arizona, this is really never a thing. Move on now if you want an actually knowledgeable reply :)

You're still reading. Okay, well, that's on you. You want a number in knots for how much difference it's going to make?? There's so much detailed measuring and *Science* that goes into that that's never going to happen, just file it under "frost makes my airplane likely to kill me" and move on.

Oh, and to answer your first question more specifically -- no, I have no living friends who have flown with frost on the plane.

Good luck...
 
deyoung said:
no, I have no living friends who have flown with frost on the plane.
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How many friends of yours have died because they flew with frost on their planes?
 
Is it a particularly good idea? No. Can it be done? Absolutely.

I worked for an operator whose idea of de-icing airplanes involved us flying them around until all the frost sublimated off before we took pax onboard.

Glycol is expensive you know!
 
My C150 takes off faster (and by faster I mean sooner and higher climb rate) with some patchy frost on its wings at max gross in winter (negative density altitude) than it does with one person at 90 degrees in summer (2400’ density altitude). Since it is impossible to have a hot day on a day with frost, I am relatively unconcerned about light frost on the rough non laminar old Cessna wing.

I do keep a bottle of RV glycol on hand to spray down the winds and tail for heavy frost, but I don’t wait till it is completely totally done before flying.
 
birdus said:
How many friends of yours have died because they flew with frost on their planes?
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How would you know if they had?
 
Yes, it will probably fly. Yes, you would get to wear your cool “test pilot” jacket.
 
Crap... is it that bad in the Pacific Northwest? It's 80 here in North Carolina now. It is June, after all.
 
birdus said:
How many friends of yours have died because they flew with frost on their planes?
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None of my friends, they know better. Frost changes the laminar flow and structure of the wing. Go back and re-read your PPL manuals.
 
As for most things, the answer is "it depends." But there should be no doubt that a frost coating can only decrease the efficiency of the wing. Will it be enough to cause an accident? Who knows, depending on the exact coverage and characteristics of the frost, and airplane loading, etc. What is happening is you are lowering your safety margins, perhaps to the point of the plane being unflyable. Basically, flying with frost on the wings is right up there with flying over-gross, loading out of CG limits, "stretching" your fuel, and descending below minimums on approach without having the runway environment in sight. Possible? Sure. Smart? Nope.
 
When I first started flying in Alaska, the accepted frost procedure was to polish the frost on the wings with a glove covered hand. Only the frost on top of the wing. It was perfectly acceptable to have frost on the bottom of the wing. Then load up and go.

Now the required procedure is to remove all frost before flight.
 
135 used to allow polishing the frost, and we did it numerous times in the King Air. Mostly when our PAX were in town and arriving late after dinner. We always gave an extra 10K for Vr. But then, a King Air has a big fat gentle airfoil
 
Tantalum said:
This probably is in the camp of "how many drinks can I have and still drive home"
The safe rule is "none" whether that's drinks or ice.
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Yes; a good % of frosted-wings flights probably turn out just fine. (I've done it before the new guidelines.)
But think of this; if you have clean wings you know you will never be in an accident report in which the NTSB blames your choice to leave with known contamination.
Easy choice for me.
 
birdus said:
Does anyone here have any friends who have flown with frost on the plane? I'm just wondering how significant an effect it actually has on how the plane flies. For example, if a Luscombe owner (other than me) were to fly with frost on the plane, would it stall at, say, 55 instead of 48? Would the aforementioned Luscombe owner (not me) even notice a difference?
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Part 135 pilots are required by regulation (135.227) to remove all frost, snow, or ice from the airframe before takeoff. Are the lives of paying passengers more valuable than those of your passengers? I have always considered frost to be a gazillion stall fences, creating drag not only on the lifting surfaces but also on the rest of the airframe. It is not a question of stall speed but of lift vs drag. A possibly apocryphal story is that of a pilot in Sweden who cleaned off one wing and, after being distracted, forgot to clean the other wing. If the story is true, he rolled on initial climbout.

Being a card-carrying coward, I had a long and successful career in the ice-laden Pacific Northwest by being sure that no frost was anywhere on the airplane.

Bob Gardner
flyingron said:
Crap... is it that bad in the Pacific Northwest? It's 80 here in North Carolina now. It is June, after all.
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They brought the SST to the northwest for its icing certification tests. With moist Pacific air hitting the Cascades and rising, the west slopes experience some really nasty stuff. ATC uses "ice avoidance vectors" upon request...they head you west over the lowlands west of Puget Sound and have you climb above the freezing level before turning east toward the Cascades. I would guess that similar conditions exist over on the coast, where those same winds hit the Olympic Mountains...but traffic over there is almost nonexistent.

Bob
 
Do you want to be a test pilot without any planning beforehand? Be my guest, but don't ask me to join you.

And I fly in the PNW. I'll put it more succinctly than Bob, "I am chicken. I am chicken!"
 
deyoung said:
Ok. Well.

One, I live in Arizona, this is really never a thing. Move on now if you want an actually knowledgeable reply :)

Good luck...
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My condolences. I am third generation Arizonan and have seen frost on wings many times because I live in the good part of the state. FIY the all time low in Arizona is lower that the all time low in Anchorage Alaska.
 
Here's what AC 120-58 has to say about frost on the wings:

"Test data indicate that ice, snow, or frost formations having a thickness and surface roughness similar to medium or coarse sandpaper on the leading edge and upper surface of a wing can reduce wing lift by as much as 30 percent and increase drag by 40 percent."
 
The one or two times this has come up for me I just grabbed a towel/t-shirt/whatever I had and rubbed as much of it off as I could.
 
Odds are nothing will happen, but if something does, The FAA isn’t gonna be too thrilled.
 
Bugs. What about bugs? I've had my prop end up feeling like it is covered with sandpaper from all the bugs while flying in and out of grass strips in farm country. How many bugs can you have on the wing before it's a problem? They seem to build up on the leading edge the most.
 
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Capt. Geoffrey Thorpe said:
Bugs. What about bugs? I've had my prop end up feeling like it is covered with sandpaper from all the bugs while flying in and out of grass strips in farm country. How many bugs can you have on the wing before it's a problem? They seem to build up on the leading edge the most.
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Bug splat leading edge wings and props, cleaned off at fuel stop PA-23-150 same power setting same conditions after takeoff at cruse +10 kts more.
 
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birdus said:
Inconclusive. There were a number of things that could've contributed to the crash. Very interesting, though!
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Final report should be out in a few months.

Cheers
 
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