Is icing a risk with non visible moisture?

Mohamed Ahmed

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Hello,

Few days ago in GA we had low temperature up to freezing. On the day of my flight that I canceled, temp was 2c and dew point was m1c, but humidity was 80%. I canceled my flight for fear of icing. Next few days, a friend of mine told me that he always flying in this conditions.

My question is was I exaggerating my concerns and no icing can happen unless it is visible moisture (IMC)?


Thank you
Mohamed
 
My question is was I exaggerating my concerns and no icing can happen unless it is visible moisture (IMC)?

Correct. If you’re in clear air, you won’t get any structural icing. The flip side to that is carburetor ice, which can occur in clear air if the atmospheric conditions are favorable.
 
The flip side to that is carburetor ice, which can occur in clear air if the atmospheric conditions are favorable.
And they were very favorable. Only a three-degree spread.

If he was carbureted, that is.

carbice.gif.7037f1ad4a8f57849b8d861aebcba6d6.gif
 
Hello,

Few days ago in GA we had low temperature up to freezing. On the day of my flight that I canceled, temp was 2c and dew point was m1c, but humidity was 80%. I canceled my flight for fear of icing. Next few days, a friend of mine told me that he always flying in this conditions.

My question is was I exaggerating my concerns and no icing can happen unless it is visible moisture (IMC)?
It's the "IMC" in your question which leads me to respond.
"Visible moisture" is not necessarily IMC. I picked up ice last year on a hazy, humid, cold day last winter with a good 6-8 miles visibility.
 
I just started carrying around that carb ice chart and check it before the flight. Too many instances of carb ice causing issues and I am flying a 150 with the carb ice prone o-200. But in cold temperatures the little engine actually has enough power to fly with carb heat on during cruise if necessary. I always put it on under 2100 rpm, but will check the chart and use it on anything under full power if I’m close to that red area.
 
It's the "IMC" in your question which leads me to respond.
"Visible moisture" is not necessarily IMC. I picked up ice last year on a hazy, humid, cold day last winter with a good 6-8 miles visibility.

That was my concern as well. Is there is a way to make good judgement for go/no go in these conditions?


Thank you
Mohamed
 
That was my concern as well. Is there is a way to make good judgement for go/no go in these conditions?


Thank you
Mohamed
It likely won't accumulate very quickly if it's not IMC. While you can get it outside of IMC I would still fly but keep an eye on it. If you notice ice forming, then you are in known ice and must get out of it. Most likely by landing.
 
Few days ago in GA we had low temperature up to freezing. On the day of my flight that I canceled, temp was 2c and dew point was m1c, but humidity was 80%. I canceled my flight for fear of icing. Next few days, a friend of mine told me that he always flying in this conditions.

My question is was I exaggerating my concerns and no icing can happen unless it is visible moisture (IMC)?

Yes, you need visible moisture for icing. It does not have to be IMC, though, low visibility (ie mist) can cause it as well, but that is visible moisture. I've iced up a Super Cub in those conditions:

IMG_0611.png IMG_0612.png

But, "high humidity" won't do it, regardless of the FAA's misguided former take on the subject, which is thankfully no longer in effect.
 
80% humid clear air won't be a problem. You need 100% humidity - that is visible moisture. Clouds, fog, mist, drizzle or freezing rain if you want ice. When its cold, snow is generally not a problem, just stay below the cloud it comes out of. Flew for 3 hrs in the snow last Friday night, not even a trace of ice.
 
That was my concern as well. Is there is a way to make good judgement for go/no go in these conditions?


Thank you
Mohamed
Low temperature/dew point spread coupled with relatively low visibility is a clue. Checking conditions at other nearby airports can also help with the decision. Forecasts - what's predicted now and in the near future? Watch METAR over time. Clear at your base, but clouds forming at another airport nearby can be a telltale clue. Is this one of those days in which you can look out the window and see clouds forming and unforming almost minute to minute? Remember, 80% humidity on the ground does not necessarily mean 80% at altitude. And it can change with direction and terrain.

When it happened, we were on a local flight. We cut the flight short and landed. On a longer flight, I would first try changing altitudes or direction. This kind of thing can be very localized. Ultimately, divert and land, just as with encountering any othe in-flight condition beyond your and your airplane's capabilities.

It's what being PIC is all about.
 
Fortunately, that particularly moronic answer to a question which should not have been asked was never actual policy.

Hello midlifeflyer,

Thank you for your detailed reply, but I disagree about the “to a question which should not have been asked”. Any question can be asked. There are no bad questions, and good pilots always learning.


Thank you
Mohamed
 
Hello midlifeflyer,

Thank you for your detailed reply, but I disagree about the “to a question which should not have been asked”. Any question can be asked. There are no bad questions, and good pilots always learning.


Thank you
Mohamed
Normally that's true, but in this case, the question was was asking for a legal interpretation from the FAA to hopefully get something different than what the FAA had been saying for many years, not asking a question for the purpose of learning.
 
Hello midlifeflyer,

Thank you for your detailed reply, but I disagree about the “to a question which should not have been asked”. Any question can be asked. There are no bad questions, and good pilots always learning.


Thank you
Mohamed

Actually there are bad questions. Especially when the answer goes completely against regulations and unless you want to fight the FAA in court over it, where the FAA is also the judge and jury, you're bound by the answer. Personally, I ignore a lot/all of CC interpretations that are against the regulations. But there are bad questions.
 
Actually there are bad questions. Especially when the answer goes completely against regulations and unless you want to fight the FAA in court over it, where the FAA is also the judge and jury, you're bound by the answer. Personally, I ignore a lot/all of CC interpretations that are against the regulations. But there are bad questions.

Again, I don’t believe that there are any bad questions. There are always bad answers.

If the question is against basic logic or physics (not just regulations that can change), we need to redirect the question to the right path, side pilots can learn and we properly share what we learned. If someone believes that he/she offended by the question, I suggest not to answer or better just block the user who ask bad questions.

For the rest of the pilots: PLEASE DISREGARD NEGATIVE NARRATIVES. There are NO bad questions, but sometimes bad answers from who cannot properly address your questions.


Thank you
Mohamed
 
There are bad questions Mohamed, but I don't think the posters are talking about your question.
 
Hello midlifeflyer,

Thank you for your detailed reply, but I disagree about the “to a question which should not have been asked”. Any question can be asked. There are no bad questions, and good pilots always learning.


Thank you
Mohamed
You might not have the experience to understand the history of the comment. There are activities which pilots have done for decades, certain of legality. Then someone gets the idea of asking the FAA Chief Counsel's office, which is, more or less, the final word of the FAA's technical legal position on the subject. They get an unexpected answer which is contrary to what had been standard operating practice and understanding.

The one about "known icing" is an infamous example. The FAA's attitude toward enforcement has always been (summarizing), if you enter icing conditions which were forecast or reported by other pilots, pick up ice, don't use an exit strategy , and cause a problem, we are going to nail you. Worked well for years. Then, a pilot wrote to the Chief Counsel for a "clarification," which came down to, if the temperatures are low and the humidity is high, you are in violation even if you never get a trace of frost. It caused quite a hubbub and the Chief Counsel eventually retracted the interpretation, even taking the unusual step of pre-publishing the replacement for public comment. The replacement was basically what everyone already knew before the question was ever asked.

It's not the only example.

And it's not about "the only bad question is the one not asked" as part of the learning process. It's about asking for an official interpretation when it's completely unnecessary.

And there definitely are bad questions.My all time favorite was a guy defending himself in court on an assault charge. Brilliantly cross-examining the victim, he asked, "How could you identify me? Your back was turned when I hit you!"
 
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Again, I don’t believe that there are any bad questions. There are always bad answers.

If the question is against basic logic or physics (not just regulations that can change), we need to redirect the question to the right path, side pilots can learn and we properly share what we learned. If someone believes that he/she offended by the question, I suggest not to answer or better just block the user who ask bad questions.

For the rest of the pilots: PLEASE DISREGARD NEGATIVE NARRATIVES. There are NO bad questions, but sometimes bad answers from who cannot properly address your questions.


Thank you
Mohamed

I was referring to the questions asked of the Chief Counsel's office, not the questions asked here. Generally most of the questions asked here are pretty good. Unless it's logging question....:eek:
 
There are bad questions Mohamed, but I don't think the posters are talking about your question.

I understand that Paul, but I’m concerned about spreading the culture of not asking for fear of public shaming. In aviation, good pilots can stop asking good questions and it may just kill them.

We all know that some questions can be answered by google or defy logic, but in my opinion, we should still share our inputs.


Thank you
Mohamed
 
I understand that Paul, but I’m concerned about spreading the culture of not asking for fear of public shaming. In aviation, good pilots can stop asking good questions and it may just kill them.

We all know that some questions can be answered by google or defy logic, but in my opinion, we should still share our inputs.
Not too much to worry about. That's not what anyone here was referring to when talking about bad questions.
 
I told this story here before...but can't find it...

I was flying southeasterly over NE AR one cold winter day, near Jonesboro. It was severe clear. I looked down and saw the front of my wheel pant covered with white. It was easy to see because the top 1/2 of the pant is dark blue. I puckered a bit and studied the strut's and wing's leading edges. I couldn't see any buildup on them (but, of course, they are white). I was high, 7500' IIRC, so I just kept an eye on things and kept on going.

The white "ice" on my wheel pants sublimated slowly...over 15 minutes or so...again, IIRC...it's been quite a while ago now.

Ice? I'm not sure, but I certainly picked up something in the clear air. And it looked like friggin' ice to me!!
 
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I told this story here before...but can't find it...

I was flying southeasterly over NE AR one cold winter day, near Jonesboro. It was severe clear. I looked down and saw the front of my wheel pant covered with white. It was easy to see because the top 1/2 of the pant is dark blue. I puckered a bit and studied the strut's and wing's leading edges. I couldn't see any Hilda's up on them (but, of course, they are white). I was high, 7500' IIRC, so I just kept an eye on things and kept on going.

The white "ice" on my wheel pants sublimated slowly...over 15 minutes or so...again, IIRC...it's been quite a while ago now.

Ice? I'm not sure, but I certainly picked up something in the clear air. And it looked like friggin' ice to me!!


Well that's what happens when you surf the cloud tops! :D
 
Hello midlifeflyer,

Thank you for your detailed reply, but I disagree about the “to a question which should not have been asked”. Any question can be asked. There are no bad questions, and good pilots always learning.

Just in case it wasn't clear already, he wasn't talking about your question, or asking questions in general. He was talking about someone asking the FAA's Chief Counsel about icing, and they gave an answer that was not consistent with reality... But that answer carries the weight of the FAA, so it had to be complied with, at least in theory. Post 21 has the details.

It's always OK to ask questions of your fellow pilots, CFIs, etc... But think really hard before you ask the FAA, because they don't always get the answers right. Remember, it's lawyers writing the answers there, not pilots.
 
Got some ice in VMC, at 9.5K; noticed it on the top of the tires of the 172 I was flying. Not much, for sure, and it built slowly. No clue if there was any on top of the wings - it just surprised me that it occurred clear of clouds and precip. I had to up there quite a while, but it was mire interesting than worrisome.
 
I just started carrying around that carb ice chart and check it before the flight. Too many instances of carb ice causing issues and I am flying a 150 with the carb ice prone o-200. But in cold temperatures the little engine actually has enough power to fly with carb heat on during cruise if necessary. I always put it on under 2100 rpm, but will check the chart and use it on anything under full power if I’m close to that red area.

I fly a C-140 with the 0-200s sister the C85 whom shares the same carb ice tendencies... Like many things in flying we must channel certain fears into healthy respects if that fear if its a legitimate one, carb ice is one. I have a policy the carb heat is on during warming up the engine and on all through the run up... turning it off is the second to last thing on my checklist prior to take off... the quick burst of carb heat to check its functionality is not enough imho... The engine is running the same basic way it is in the pattern where you would never think of being without carb heat...

I think running it full time at cruise is overkill myself, but I make it a practice to hit it full on periodically for a few mins at a time, usually coinciding with seeing a great off airport landing spot... Just what makes sense to me...
 
Frost(ice forming directly from water vapor) can certainly occur in clear air if you fly from below freezing area to a warm, humid area.

It should be very brief though
 
Seems to me as if a low time pilot with little knowledge is dismissing what is posted by two high time CFIs, one of which is an attorney well versed in such matters. This site certainly keeps me amused.
 
Got some ice in VMC, at 9.5K; noticed it on the top of the tires of the 172 I was flying. Not much, for sure, and it built slowly. No clue if there was any on top of the wings - it just surprised me that it occurred clear of clouds and precip. I had to up there quite a while, but it was mire interesting than worrisome.

Uhhh... That doesn't sound like icing to me. The top of the tires would be about the last place you would see ice if it were something that had happened in flight.
 
Seems to me as if a low time pilot with little knowledge is dismissing what is posted by two high time CFIs, one of which is an attorney well versed in such matters. This site certainly keeps me amused.

What are you talking about? I don't see anyone being dismissed except when the OP thought, in post 18, that the CFI attorney was calling his question stupid in post 14. (Hint: He wasn't, he was talking about the idiot that asked the Chief Counsel's office for the official interpretation of "known icing" and got a reply that, while it may have sounded great to a lawyer, didn't have much to do with the reality of piloting, or physics.)
 
Seems to me as if a low time pilot with little knowledge is dismissing what is posted by two high time CFIs, one of which is an attorney well versed in such matters. This site certainly keeps me amused.
He wasn't. And I can't speak for anyone else, but I'm not particularly high time.
 
Seems to me as if a low time pilot with little knowledge is dismissing what is posted by two high time CFIs, one of which is an attorney well versed in such matters. This site certainly keeps me amused.

@DutchRoller no one is dismissing anything. We all values the inputs and experience sharing. This is priceless.


Thank you
Mohamed
 
Uhhh... That doesn't sound like icing to me. The top of the tires would be about the last place you would see ice if it were something that had happened in flight.
Yet there it was. . .warm(er) tire condensing mositure from the air, then freezing at altitude? Or some other phenomena - whatever the mechanism, it produced little snow cones on both tires that had originally left the ground dry.
 
Yet there it was. . .warm(er) tire condensing mositure from the air, then freezing at altitude? Or some other phenomena - whatever the mechanism, it produced little snow cones on both tires that had originally left the ground dry.

I'm not sure what phenomenon you witnessed, but it's not consistent with airframe icing in the traditional sense. If you're picking up ice, it'll be on the leading edges, and it would have to be fairly severe to end up on the tires because it accumulates first and fastest on the smallest-diameter curves. Sounds like you were flying a Cessna if you could see the tops of the tires, and the best place to look for icing on a Cessna is usually the fuel vent tube. On my Mooney, I look at the stall strips and the little shield just inboard of the nav/strobe lights. Cherokee types, use the OAT probe, etc.

Also, for the tire to be condensing moisture from the air, it would need to be colder, not warmer. I have no explanation for what you saw.
 
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