snippercr

I am trying to remember my instrument rules and sadly I am not sure the nature of icing conditions (maybe because I trained over a summer and stupidly didnt pay too much attention to icing).

If you are flying in an aircraft that says flight into known icing conditions is prohibited (IE most small GA aircraft), is that basically flight in the clouds above freezing level or only when there is an air/sigmet out for icing? I want to do some IFR time building and the cold midwest weather keeps the clouds nice and low so I can get some actual time. However, it also means the freezing level is always at the surface.

Thanks!

Edit: I think I found my answer here with a very good article: http://www.ifr-magazine.com/defining...n_faa_ifr.html

Basically: NO - flight into IMC with temp at or below freezing consitutes "known" icing conditions and in an aircraft prohibited for said flight, it would be a operational violation.

Ewfflyer

Icing is, and will be for a long time a "gray" area. The only actual "Known" icing is from Pireps. There's prediction info etc..., but it's not always accurate, and covers vast areas. I'm not saying it's good/smart/safe to attempt flying is (0)-(-10) temps and in clouds with a single-engine, small GA plane, because it isn't. Something with more horsepower, prop-protection at a minimum, and speed, usually is more apt to handle these adverse conditions.

snippercr

the question started off more as a safety thing, then I started wondering about the legality of it. I was worried about going into clouds and actually getting ice, now I know its just plain illegal which will keep me VFR for a while. it sticks cause now I have constant easy to access 1000 feet cigs with often low vis that Id just love to jump into and get some actual. Oh well, this is aviation.

rickair7777

It's not illegal to fly into conditions which might be conducive to icing, even in a non-ice airplane.

If icing was forecast, it's still technically not "known icing" but you could get in trouble if you got iced up and had to declare an emergency.

A PIREP is considered known icing.

I'm not advocating flight into possible icing, but a little light rime in the cloud tops is very common and is not likely to harm most GA aircraft. Cessnas can carry a lot of ice and still fly. I mention this so that if you do get into a light light rime at the freezing level you don't panic and do something silly (or dangerous). First order of business is to get out of the icing, then evaluate how much is still stuck to the airplane, and how that will affect the performance for the remainder of the flight. A precautionary landing at a nearby airport might be a good idea if it doesn't melt by itself.

iahflyr

How do you determine the freezing level?

Lets say it is 15 degrees C at the surface. Do you just use the standard lapse rate of -2 degrees C per 1,000ft, or is there actually a forecast freezing level that you can be forecasted? How do you get this information (either online or can you get it from a FSS briefing).

iflyjets4food

question answered...

there's a chart that has it depicted along with many other things, but I don't recall what it was called. Airmets should give you the freezing level as well.

patton33

i use www.aviationweather.gov

There is a freezing level product there although in lieu of that and airmets, nothing wrong with using a winds aloft or pireps.

Niner

Instructing in Western New York the only way to fly in the winter is to go in the clouds when its below freezing. Just be smart about it and you'll be ok. If there are a lot of PIREPS for icing stay on the ground but if there aren't any then go up and see if you get any ice. I usually just file to an initial approach fix for an approach at our airport and shoot a couple approaches there. That way if you pick up ice you can just call it quits after one. Just make sure you always leave yourself an out.

SongMan

I got couple questions of my own and tought I would ask on this thread instead of starting a new one since it's about icing.

-Why would you climb intead of decending when you encounter icing?

-How can you get icing on a below freezing(32F or less) condition when all the moisture is already frozen? ex;How can you get moisture on the wing to create icing when all the moisture is already frozen before making a contact with the wing?

Sorry for such a elemantary questions. Just never really understood icing either.

Thanks!

the King

1. There's a possibility of a temperature inversion or potentially climbing to VMC when the clouds and freezing level are low. Not guaranteed, but possible. The #1 priority is to get out of the ice. If you are IMC and have no way to tell where the ground is, best bet is to climb. No one has ever collided with the air.

2. Water droplets can actually be cooled below freezing without turning to ice. This phenomenon is called super-cooled water droplets. The water has nothing to freeze on since it is suspended in the air. But if it is super-cooled, the moment it touches something (wings) it will freeze. Below -20 degrees it is highly unlikely there is anything liquid, but between 0 and -20, you have to beware of the potential for ice.