Frost question

jspilot

jspilot

Cleared for Takeoff
Joined
Oct 22, 2011
Messages
1,346
Display Name
Display name:
jspilot
Went flying this Sunday. Beautiful day but there was frost. As usual the FBO cleared off the wings and rudder and control surfaces but missed the front of the tail. I had the guy come back and clear it off but I was just wondering if this was actually required or was I being overly cautious? Obviously frost on a control surface or wings is a no go but the front of the tail had me confused. My concern was the frost may disrupt the air flow over the tail which could lead to less rudder authority but I’m honestly not sure.

This is flying in a 172.
 
Last edited:
I was thinking it was required to be cleared but that’s large / turbine aircraft. Probably wouldn’t be an issue for just the leading edge of a vert stab. But you’re PIC.
 
You did the right thing, no frost on wings tail, rudder, flaps or control surfaces. Get rid of it before you fly, don't get trapped into the how much is too much game. Any on those surfaces is too much.
 
jspilot said:
Went flying this Sunday. Beautiful day but there was frost. As usual the FBO cleared off the wings and rudder and control surfaces but missed the front of the tail. I had the guy come back and clear it off but I was just wondering if this was actually required or was I being overly cautious? Obviously frost on a control surface or wings is a no go but the front of the tail had me confused. My concern was the frost may disrupt the air flow over the tail which could lead to less rudder authority but I’m honestly not sure.

This is flying in a 172.
Click to expand...

I assume you are referring to the leading edge of the vertical stab, and not the leading edge of the horizontal tab. Both are lifting surfaces and need to have laminar flow in order to function properly. But if I were to pick one, I would say horizontal stab is more important since it can affect stall speed and pitch control. If unsure, clean all surfaces, which is exactly what you did.
 
You made the right choice. Honestly, in the vast majority of these types of situations there is no reason not to take the most conservative path.
 
What Sarangan said. Leading edge of the horizontal stabilizer is the most critical surface on an airplane. Actually the front-bottom side of the horiz stabilizer is probably most critical (the stabilizer provides a down force for controlled flight) except that surface doesn't get contaminated very often. But you don't want to be a test pilot when it comes to frost.:oops:.....

Good move.
 
Do you ever practice for a tailplane stall in a 172?

Yeah, me neither. Good move.
 
Other than scraping Frost and ice off, what else works well?? someone said RV antifreeze, but would that be applied using a weed sprayer??.. I am now living and flying in the snow zone, and parking outside as there are no hangers.... need to learn more about this condition.
 
Glenn D said:
Other than scraping Frost and ice off, what else works well?? someone said RV antifreeze, but would that be applied using a weed sprayer??.. I am now living and flying in the snow zone, and parking outside as there are no hangers.... need to learn more about this condition.
Click to expand...
I thought some people used the same fluid that goes into a FIKI system (TKS???) Maybe the RV stuff does the same job cheaper - I am curious as well?
 
If you use RV anti freeze in a weed sprayer (which I do occasionally) make sure to get an all metal sprayer can and heat the fluid on the stove right before you go to the airport. It’ll stay warm for the drive. Warm fluid is 100x better than cold fluid. And do it right before you’re ready to go so the motion of flight clears the fluid.

Good wing covers are way easier than spraying the wings!

Nothing clears the frost like sublimation. ;)
 
Glenn D said:
Other than scraping Frost and ice off, what else works well?? someone said RV antifreeze, but would that be applied using a weed sprayer??.. I am now living and flying in the snow zone, and parking outside as there are no hangers.... need to learn more about this condition.
Click to expand...

I think you've got covers in your future. Bruce's aren't cheap, but they'll work.
 
On days like this I’ll rub my hand on the vertical fin to knock down rough frost but I have no concern about smooth frost. To some extent that’s true for wings and horizontal as well, but there’s no frost under the covers in this picture.



F7AA860F-72DB-4800-BF64-B843B5729BD3.jpeg
 
Turn the frosted surfaces so they are exposed to the sun if it is out, after a half an hour or so they are usually frost free. In most cases, at least around here, the underside of wings generally don't get frosty.

Smooth frost, rough frost, no frost is good frost.
 
All should be cleared, also you should start with the pilots side wing, that way it’ll be the first that will show contamination and it’s the surface you should look at as a reference
 
Last edited:
Can you see the top of your Skywagon wing from the seat?

What frost you may miss dissipates very quickly in flight. So does clear ice, the kind that forms under wing covers as temps bob above and below freezing. Can't scrape that hard ice off and RV anti freeze barely touches it. It it's smooth? I fly it off.
 
Stewartb said:
Nothing clears the frost like sublimation. ;)
Click to expand...

Yes, it does.. :lol::lol:

For years in Alaska I did the frost polish with my glove and a push broom. But now the FAA wants the frost cleared, not just polished smooth any more.

One time in Bethel I spent an hour clearing ice and frost from the C-207. Then the NG heli parked next door took off and flew over our ramp covering everyone with frost again. :mad3: :incazzato:

Parking in a warm hanger is Ok to remove frost, just be sure the plane is dry when taking it out again so any water doesn't re-freeze in places where ice is not wanted..
 
Used to be, Part 135, all one had to do was polish the frost to smooth. That changed about 10 years ago.

Actually did do that a couple of times, always increased Vr 10 knots. Never had a problem.
 
as far as using RV antifreeze or just plain glycol, none of them have any separation speed rating, if you are using any of them, make sure its off/dry off any control surfaces.
 
Separation speed rating? What the heck is that?

Been using RV anti freeze for 25 years and it works great. Wait, make that 20 years. The first 5 years I used aircraft deicing fluid but found out RV stuff works just as well at a fraction of the price. It really is all about the fluid being heated.
 
Stewartb said:
Separation speed rating? What the heck is that?

Been using RV anti freeze for 25 years and it works great. Wait, make that 20 years. The first 5 years I used aircraft deicing fluid but found out RV stuff works just as well at a fraction of the price. It really is all about the fluid being heated.
Click to expand...
https://en.wikipedia.org/wiki/Deicing_fluid
speed at which the fluid will separate from the surface.
 
Thanks for the feedback guys. To clarify, I mean the front side of the vertical stabilizer. The horizontal stabilizer was cleared. The FBO line guy is a pilot too so my hunch is just oversight or rushing, but either way, glad I didn't just go for the flight!
 
Stewartb said:
Separation speed rating? What the heck is that?

Been using RV anti freeze for 25 years and it works great. Wait, make that 20 years. The first 5 years I used aircraft deicing fluid but found out RV stuff works just as well at a fraction of the price. It really is all about the fluid being heated.
Click to expand...

Why not just get type 1

I hear there are some not so friendly things in RV coolant.

Stewartb said:
Can you see the top of your Skywagon wing from the seat?

What frost you may miss dissipates very quickly in flight. So does clear ice, the kind that forms under wing covers as temps bob above and below freezing. Can't scrape that hard ice off and RV anti freeze barely touches it. It it's smooth? I fly it off.
Click to expand...

That was more from work, point is pick the part you’re going to reference and deice it first.
 
Not friendly things? What things? This stuff is intended for anti freeze in potable water systems.
 
jspilot said:
Thanks for the feedback guys. To clarify, I mean the front side of the vertical stabilizer.
Click to expand...

That area may not need any ice removal. For instance the King Air has deice boots everywhere except the front of the vert stab.

king_air_200_raisbeck.jpg
 
Clip4 said:
Once upon a time and not all that long ago the FAA said just polish the frost smooth.
Click to expand...

Yep, did that a lot in the olden days in the bush. Usually used a glove to knock off the ruff stuff and go. Never worried about frost under the wing because of cold soaked fuel.
 
Zeldman said:
Yep, did that a lot in the olden days in the bush. Usually used a glove to knock off the ruff stuff and go. Never worried about frost under the wing because of cold soaked fuel.
Click to expand...

Rather certain in the bush they still just polish the frost smooth.
 
I’d say the chances of bugs built up on the leading edge of a vert stab would have just as much effect.
 
Last edited:
Clip4 said:
Rather certain in the bush they still just polish the frost smooth.
Click to expand...

Lots of bent aluminum and gut piles in the bush too.

Wing covers or proper de ice, if you can’t afford covers and/or a backpack sprayer and some type 1 and hot water, you probably should just stick to your F150.
 
How many bush crashes were caused by frost? If you make such an assertion you must have some knowledge to back it up. ;)

It's fine to remove it all, obviously, but these attitudes that ANY frost is certain doom? Not true. Not even close. If you want to learn? Listen.
 
Stewartb said:
How many bush crashes were caused by frost? If you make such an assertion you must have some knowledge to back it up. ;)

It's fine to remove it all, obviously, but these attitudes that ANY frost is certain doom? Not true. Not even close. If you want to learn? Listen.
Click to expand...

How much icing time do you have?

Half the year I live in icing conditions, and
we launch into it at 3am from a deep sleep, so sorry I have nothing to learn from dumb pilot tricks, do I really need to run the NTSB search for people who got themselves killed playing with ice?
 
We aren't talking about ice. We're talking about frost. I park outdoors in Alaska. I have a fair bit of frost experience.
 
You must log in or register to reply here.
Back
Top