I need help understanding Icing

RyanB

RyanB

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Icing is a subject that i have not had great understanding of. I do understand that you can only pick up ice while flying through a cloud, but how do VFR pilots get caught in icing conditions? During preflight planning for cross countries as I call the wx briefer they give out the freezing level. I understand this is the level where if visible moisture were present the temps are cold enough to freeze and rain falling through this level could freeze and stick to your wings. I just read about an A36 on approach to land that had ice form on the wings and he lost control of it. So how is ice avoided and how do you know if you could pick it up or not, if flying VFR.

Thanks
-Ryan
 
You can be beneath clouds and pick up freezing rain in the form of clear icing. Either moisture lifted to a freezing level or rain falling from a temperature inversion. That's why you'll see it's common for some aircraft to require anti-icing devices to be on in temps 4-5 degrees or less and in visible moisture. Personally never had icing form above 0 degrees but it can happen.
 
Velocity173 said:
You can be beneath clouds and pick up freezing rain in the form of clear icing. Either moisture lifted to a freezing level or rain falling from a temperature inversion. That's why you'll see it's common for some aircraft to require anti-icing devices to be on in temps 4-5 degrees or less and in visible moisture. Personally never had icing form above 0 degrees but it can happen.
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But that can only happen while the OAT is below freezing or while in the freezing level?
 
Or flying in FZRA, FZBR, etc. fly below freezing, under a inversion, get rain that sticks.

Anytime its near freezing and there is visible precip.

You can look at the airmets for ice, PIREPS, temps aloft and TAFs, etc. All else fails call a briefer.

Keep in mind things arnt always as advertised, keep a eye on the OAT (should be part of your scan for most GA IFR folks), if you're gettin near the danger zone keep a eye on your struts, tires, temp probe sticking out, etc for ice buildup, don't be afraid to ask for lower, don't be afraid to TELL them you're in ICE and TELL them what you need/want.
 
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Also remember for carburetor icing, the temperature does not have to be below freezing to get icing.
 
James331 said:
don't be afraid to TELL them you're in ICE and TELL them what you need/want.
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Not disagreeing with you, but I have lost track of how many people have said 'just ask for lower- never tell ATC that you are picking up ice because the FAA will come after you!'

Has anyone ever heard of the FAA going after someone for making an ice PIREP in a non-FIKI airplane?
 
Ryanb said:
But that can only happen while the OAT is below freezing or while in the freezing level?
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Not necessarily. Aerodynamic cooling can occur a few degrees above freezing. The airflow goes over a curved surface and cools as it's static pressure is reduced. For instance, the UH-60 requires pitot heat and anti-ice to be on during conditions of visible moisture with temps 4 C or below. Like I said, I've flown in rain above 0 degrees before and haven't noticed any significant accumulation but it can happen.
 
Fearless Tower said:
Not disagreeing with you, but I have lost track of how many people have said 'just ask for lower- never tell ATC that you are picking up ice because the FAA will come after you!'

Has anyone ever heard of the FAA going after someone for making an ice PIREP in a non-FIKI airplane?
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D White brought that up a long time ago. He was flying a Mooney picking up icing and ATC asked if he was FIKI. He was wondering if they asked that to report him. I just laughed reading that. They don't care about reporting that. They wanted to know if he was good for FIKI to best handle his situation. Like I always say, ATC reports PDs that affect their separation or things that are automatically sent out such as TARP "snitch patch" alerts.
 
Fearless Tower said:
Not disagreeing with you, but I have lost track of how many people have said 'just ask for lower- never tell ATC that you are picking up ice because the FAA will come after you!'

Has anyone ever heard of the FAA going after someone for making an ice PIREP in a non-FIKI airplane?
Click to expand...

Even if they did come after you, which is unlikely, Id rather have to pay my way out of it then lawndart the plane.

Priorities (in order)
Skin
Tin
Ticket
 
Don't fly in precipitation when the surface temp of your aircraft is less 0C. Unless its below -25C.

Don't fly in conditions favorable for icing. When you figure out all of the possible conditions let the rest of us know.

What is there you need to know? Icing happens when precipitation or large moisture drop clouds encounter surface temps below freezing. . . stay out of it unless you have de- or anti-ice.
 
If it happens in VFR it is freezing rain, but in a cloud, above freezing (they say about 34 degrees F or so is ideal), it is possible to get ice from "supercooled droplets of water". This liquid water IS lower temperature than freezing because it descended from above where it is colder. The air that it is in now is above freezing. The water stayed liquid and did not freeze (yes that is possible). Water CAN be below freezing and still be liquid. The plane flies through it and disrupts whatever is keeping it from freezing, and presto, the liquid water turns into ice (on your wings).

The opposite is NOT true. If water is above freezing it cannot be ice. But water CAN be below freezing and stay in liquid state (Not be frozen).
 
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Fearless Tower said:
Has anyone ever heard of the FAA going after someone for making an ice PIREP in a non-FIKI airplane?
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Like McFly said, ATC doesn't want to rat you out for stuff like that. If it interferes with their job, then yes. In that instance, they are just trying to help.
 
I was cruising along IMC at 11k (non-FIKI). ATC needed me at 13k for a few miles due to MEA on the airway.

Started slowly picking up ice, but was not worried since it was only for a few miles and I was headed back down.

Told ATC and they were really helpful. They were actually more worried than I was, I think. When I got to a certain point they gave me a vector that corresponded with the airway and cleared me lower. I suspect their MVA was lower than the MEA on that segment.

Anyhow, very helpful, no issues.
 
Take the ' freezing level ' charts with a grain of salt. Rarely do I see them actually being anywhere close to accurate. It's fine for pre-flight planning especially in an airplane that doesn't have ice protection, and by ALL MEANS look at them!, but Pireps and Airmets are about the best tools you can use to help get an idea of where the ice is. You can have sub-zero temps near the surface and +10c at 3,000agl with a temp inversion, as an example, a freezing level chart would show the freezing level starting at the surface. Airframe ice CAN still form if the indicated OAT/RAT/TAT is above 0c.

Ryanb said:
Icing is a subject that i have not had great understanding of. I do understand that you can only pick up ice while flying through a cloud, but how do VFR pilots get caught in icing conditions? During preflight planning for cross countries as I call the wx briefer they give out the freezing level. I understand this is the level where if visible moisture were present the temps are cold enough to freeze and rain falling through this level could freeze and stick to your wings. I just read about an A36 on approach to land that had ice form on the wings and he lost control of it. So how is ice avoided and how do you know if you could pick it up or not, if flying VFR.

Thanks
-Ryan
Click to expand...
 
hkyplr18 said:
Take the ' freezing level ' charts with a grain of salt. Rarely do I see them actually being anywhere close to accurate. It's fine for pre-flight planning especially in an airplane that doesn't have ice protection, and by ALL MEANS look at them!, but Pireps and Airmets are about the best tools you can use to help get an idea of where the ice is. You can have sub-zero temps near the surface and +10c at 3,000agl with a temp inversion, as an example, a freezing level chart would show the freezing level starting at the surface. Airframe ice CAN still form if the indicated OAT/RAT/TAT is above 0c.
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I know you know this, but just because there are no PIREPS doesn't mean there is no ice.

Another trick, keep a eye on your trim indicators, if your trim is all off compared to where it normally is for that phase of flight, you might have some ice. Also if you're using autopilot, take it off once and a while and feel the plane.


Here's a good manual on air and ground icing, vis in snow, made by our Canadian friends, worth a read, good tables and even a little quiz in the back.

https://www.tc.gc.ca/Publications/en/tp10643/pdf/hr/tp10643e.pdf


Here's a FAA AC on it. The Canadian one is a little better, but this covers some areas the canada one doesn't.

http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_91-74A.pdf
 
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Fearless Tower said:
Not disagreeing with you, but I have lost track of how many people have said 'just ask for lower- never tell ATC that you are picking up ice because the FAA will come after you!'

Has anyone ever heard of the FAA going after someone for making an ice PIREP in a non-FIKI airplane?
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In a conversation with the then-Assistant Administrator for Certification and Regulation, he told me that the FAA would seek administrative action ONLY if a pilot reported picking up ice and failed to take action to get out of the icing conditions. Even FIKI airplanes don't get a free pass...all they buy is more time to escape the conditions. As I recall, the certification standard in stratus clouds is 26nm (beyond that you are a test pilot) and in convective conditions the standard is 3.8 nm with the same caveat.

Unless the controller is a pilot, chances are that s/he has no clue about the icing certification status of a given aircraft model. And they hate paperwork with a passion.

Controllers react positively to the words "ice" or "icing," and will do what is necessary to get you out of the icing conditions. Saying nothing is foolhardy.

Bob Gardner
 
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