OK, so now how about ice?

[James_Dean]

Don't let this happen:

Where do you find clouds of lucite?


James Dean

 

[jesse]

I prefer to take off with no gas.

I like to takeoff with no oil, It's pretty cool listening to the engine SCREAM as metal rubs on metal. It's a good way to practice an engine failure.

 

[Pilawt]

And with the FAA, who will take the ticket of anyone they catch intentionally flying into what they call "known icing conditions" in an aircraft not equipped and certified for such flight. And the FSDO's up your way do not seem to have any "Northwest" exception to the rule

Ron, does FAA take the position that (visible moisture) + (forecast temp aloft of 0C to -40C) = automatic bust? The language in the Curtis decision ("[...] respondent should have known from the weather forecasts that there was a reasonable possibility he would encounter icing") seems to suggest it does.

I realize there was other evidence against Curtis (pireps, etc.), but this sounds like a new definition of what "is" is: "reasonable possibility" is the same as "known."

Likewise, does a "NO SIGNIF ICE EXP" comment in the weather briefing take it out of "known ice" category, assuming no pireps to the contrary? (Last year I flew from Portland to Seattle, forecast freezing level at 8,000 on the back side of a drying, dissipating front, "NO SIGNIF ICE EXP" in the briefing. I started picking up ice at 6,000, and got out of there quickly.)

-- Pilawt

 

[spiderweb]

Well, Ben you have to get out here in the midwest in the winter and do it in a K-ice bird...

I would love to!

 

[spiderweb]

OK, I'm sitting out here at FDK at the public computer. It is pretty obvious that it is a nice flying day, so I'll be off in about an hour. Thanks guys!

 

[SkykingC310]

So now it seems this has turned into a big joke. I want to apologize to everyone and say I AM SORRY. I've enjoyed reading the posts on this website and would like to continue participating. I will act more mature in the future. I feel priveledged to be a part of such an elite group, known as pilots, and I wish us all safe flying. Please accept my apology.

 

[SkykingC310]

I feel it necessary to describe my first experience with ice so that my point might be clarified. I was training for my instrument rating. I was fairly well into it and had been blessed, I believe, with many IFR training flights in actual conditions. Up to this point, the conditions had been such that icing was never a factor. One day, I arrived at the airport for a scheduled lesson with my instructor. We were planning on doing some local approaches. I would be wearing the hood this day because the ceiling was higher than we would be flying. Actually, the clouds were overcast at 6000. We would only be climbing to 4000. Now, understand this is in or around Portland, Oregon, where the terrain is nearly at sea level, so we had 6000 feet of VMC.

Anyway, as I presented a weather briefing to my instructor, I noted that the freezing level was sitting between 6500 and 7500. Pilot reports stated light rime ice climbing and descending through those altitudes in the area. To make a long story short, we requested, and were cleared, to climb in a holding pattern over the Battleground VOR. We were able to maintain 6000 in the hold and were in and out of the bases. No ice. We climbed and maintained 7000 in the hold. Yes ice. It did not accumulate very quickly at all. We stayed a while, knowing we were only 1000 feet above the bases and had another 6000 feet below that of warmer temperatures. The area around the Battleground VOR is flat with many open fields as well as many airports in case we had to land. The experience, for me, was very valuble. I was able to see and understand that even a trace of ice makes the airplane handle differently. As more ice accumulated, I had to add power to maintain altitude. At the point when full power was being used and holding altitude was becoming difficult, we asked for a descent and were in the clear in two minutes. As we flew home in VMC and temps above freezing, I got to watch the ice shed off. I enjoyed the flight because I was able to learn a valuble lesson in a safe manner, while at the same time, earning a respect for ice. Now I know what it can do and how quickly it can ruin your day and it's not just something I've read about.

Aircraft rental = $89/hr.
Instructor = $35/hr.
A safe lesson on in-flight icing = Priceless

 

[Greebo]

That's a good story, Adam, but I have to ask you a question:

How were you able to predict the rate at which ice would accumulate, and thus predict how long you could safely stay in icing conditions?

I'm willing to bet a steak dinner that you couldn't predict the accumulation rate. If so, that means you and your instructor entered conditions in which you added variables to your flight that were unpredictable, and more importantly, completely avoidable.

What would you have done had the rate of icing been faster than your ability to compensate?

What would you have done had ATC refused clearance to descend due to traffic below?

You say you know what ice can do - but how can you justify that statement when, as far as I can tell, there isn't a reliable way to predict how quickly ice can form?

 

[grattonja]

You have shared a salient and useful training story for us. And I do appreciate that. I lived to tell about my icing experience and so did you, so it is all good.

But there are what ifs to your experience. What if, while up at 7000 feet, your radios froze over? This is, I am told, not an uncommon occurrence when they get enough build up on them. Now you MUST decend, and can't call for clearance to descend, making this a circumstance where you have to (potentially) deviate from the regs. If you had an efc time that you could meet before too much ice built up, no problem. Ride to the efc and get out. If not, then you are a lost com, deviating from clearance situation, which means you have gone up into known icing and basically had an declarable situation in the eyes of the FAA. That would be, according to what Ron L tells us of enforcement actions, a likely bust.

This is just one "what if" I can come up with. Obviously there are others. While your learning experience was an excellent one for you, and ended up being without incident, I'm sure you can see how this can also end up poorly.

Ice is an incalculable. Even people who fly KI planes will say it is very difficult to predict when it will be there, how quickly it will build up and what it will do.

Again, in no way am I dissing you or your training story. It was great, and it is good to hear that people are learning real IFR flying lessons. I worry sometimes about folks who get the IR, never having been in actual, and don't go in actual until that first time when the weather is hard/low IMC, cold, convective, etc. That ain't the time to learn.

Thanks for sharing your experience.

Jim G

 

[Dave Siciliano]

Thanks Adam. It's nice to hear your story. As you can tell, lots of folks get worked up about this.

I've been in some icing conditions in a non K-ice plane but the conditions changed while I was in the air on a long cross country trip. I can see how getting some experieice can be very helpful so one doesn't panic. OTOH, I think we're all saying it sould be done in a calculated manner with lots of outs; preferrably in a K-ice plane. Some people have a different opinion. Some say, no foul, no harm, but, as you can see, many folks feel it shouldn't be messed with at all.

You have to deal with those conditions a lot out where you are. Sounds like you left some outs, but as been pointed out, it could have lead to problems. If your instructor did this with you, you should appreciate that he could have lost a lot if his calculations had been wrong. Also, there may be some things folks do that they don't publish in a public forum

 

[AirBaker]

I think one of the problems is not knowing how your plane handles ice until you've got it. How much ice can it carry? Do you need to get out of it at the first sign of it?

While it would be great to see it in a k-ice plane, I'd want to know what my tolerances are.

 

[Greebo]

I think one of the problems is not knowing how your plane handles ice until you've got it. How much ice can it carry? Do you need to get out of it at the first sign of it?

In other words, how willing are you to be a test pilot.

Me? Not very!!!

 

[AirBaker]

In other words, how willing are you to be a test pilot.

Me? Not very!!!

No offense Chuck, but the problem with this statement is that it has been done. It just isn't approved in the POH. True, the icing potential is an unknown, but the knowledge would still be helpful.

My guess is that my airplane has had ice on it before, I just haven't been around to see it. Maybe I just need a video of it.

 

[wsuffa]

Adam,

Thanks for posting that story so others might learn.

My learning encounter with ice was on a late spring day between Memphis and Martinsburg at FL190. I had climbed up there to get above a bunch of moderate cumulus that seemed to top out between 17,000 and FL180. Somewhere NE of Nashville, it changed to more of a cirrus layer, while the tops gradually increased until I was in them. Based on pireps, I figured I'd be out soon. After about 10 minutes, I started to pick up a bit of rime on the airframe, shortly thereafter it started to develop on the prop. I asked for lower, and ATC told me to wait 2 minutes to clear some air carrier traffic into BNA. The ice picked up rapidly, and it was obvious that waiting any longer than 2 minutes would necessitate the "E" word. Fortunately, I got clearance down to 17,000 (which put me well into the cloud) then 15,000, where I cleared the cloud layer. Incidentally, by the time I got down to 15,000, the overhead clouds dissipated, and it was clear above. No way could I have stayed at FL190 for that long.

At 15,000, the temperature was still low enough that the ice was not sublimating rapidly. It did come off the prop fairly quickly, but it was very slow to come off the airframe. I wanted lower, but by that time I was crossing one of the arrival procedures into CVG. No problem maintaining altitude, but the airspeed was down and more power was necessary. Finally got clearance down to 13,000, where the temp was right around freezing, and the ice sublimated fairly quickly.

It was a lesson in 1) how much water vapor there is, even at higher altitudes, 2) even with turbocharging, you can't always outrun it, 3) ice builds faster and takes a lot longer to sublimate than expected, and 4) don't expect ATC to be able to accomodate you immediately near arrival corridors. BTW, there were no icing pireps, nor was the usual icing airmet/sigmet in place.

 

[James_Dean]

No offense Chuck, but the problem with this statement is that it has been done. It just isn't approved in the POH. True, the icing potential is an unknown, but the knowledge would still be helpful.

My guess is that my airplane has had ice on it before, I just haven't been around to see it. Maybe I just need a video of it.

That is a deadly game you're willing to play.

I'm sorry for getting riled up about this, but being willing to get ice on my non-KI airplane almost killed me. You do what you will, but I've learned my lesson. IMO, all the knowledge you need is

1. Don't go into icing conditions.
2. If you violate rule #1 get out of icing conditions as soon as frickin' possible.

James Dean

 

[AirBaker]

That is a deadly game you're willing to play.

I'm sorry for getting riled up about this, but being willing to get ice on my non-KI airplane almost killed me. You do what you will, but I've learned my lesson. IMO, all the knowledge you need is

1. Don't go into icing conditions.
2. If you violate rule #1 get out of icing conditions as soon as frickin' possible.

James Dean

Just so I'm not misunderstood. I'm not going to go charging off into known icing. I'm not downplaying it's danger. I'm not looking to see exactly how much ice the Bo will carry.

 

[James_Dean]

Just so I'm not misunderstood. I'm not going to go charging off into known icing. I'm not downplaying it's danger. I'm not looking to see exactly how much ice the Bo will carry.

Fully understood. I'm just saying that sticking around in icing conditions to intentionally let it build to any level is not conducive to living very long.

The fallacy is that you will pick up 1/2" during your experiment and think you know how it will affect your performance. Trouble is that all ice is different. You might be ok with 1/2" of clear ice, but 1/2" of rime will cook your goose. You don't know. You can't know.

Again, I'm sorry for getting excited about this, but I still get sweat on my brow thinking about doing the quick calc of our rate of descent and distance to the airport wondering if we were going to make it.

James Dean

 

[Dave Siciliano]

I ran into freezing rain in a TN A-36 over El Paso on the way from Dallas to San Diego. There was a frontal system that had moved east faster than forecast; when it hit the mountains at El Paso, it blew warm air on top of cold and created the freezing rain.

As I crossed the mountains just west of El Paso, the MEA was 10,000 and there was traffic there. I was at 12,000 when hard rain began hitting the plane and immediately freezing. We had just finished checking with Flight Watch as we had seen the build ups ahead and been told the tops were around FL180 and that an inversion was present; no uplifting action was specifically mentioned, but we asked the briefer if it would be better to climb or descend if we ran into ice: the briefer raised her voice and said whatever you do, don't climb, that's where the worst activity will be.

We thought through that and couldn't understand it. It was colder lower and the warm air was higher. Tops were reported to be FL180 and we could occasionally see the tops. So, we decided to climb if we ran into ice; if that didn't work, a 180 would put us back over lower terrain behind us.

When the freezing rain hit, I called El Paso Approach and told them we were encountering icing and needed an immediate climb. They told us to stand by; we began a climb. Since I was only going to climb about 700 fpm in this plane, I wanted to get started. El Paso called back a couple minutes later as we were nearing 140. They said they saw us climbing and wanted to know where we'd level off. I asked for FL180 and they approved. They asked if we were still getting ice and I reported we were, but not as bad. About 155, the ice accumulations stopped and we continued the climb to FL180. At that level we were even with tops but could easily circumnavigate build ups and stay in the clear. Probably 50 miles farther west, the buildups dissipated. Seems the system just hit the mountains, pushed up in one area along the mountains. But for a short period of time, things were very challenging.

Looking back, the Bo will carry a lot of ice. We had over an inch on the leading edges and some on the prop we couldn't measure. Of course, had the icing been worst (accumulations faster) we might not be able to climb; then, the 180 would have been our alternative. This is a capable plane for a none de-ice system aircraft. The TN will take me up to FL250 and there is alternate air induction if icing clogs the air filter. The IO-550 gives more power than this plane came with.

This encounter is one of the reasons I moved to a K-ice plane. I fly long cross country flights where the weather can change substantially while I'm enroute. I go high where ice can be encountered year around. I wanted more time to deal with ice in the future than I had here. I had to begin climbing immediately. If the controller objected, I would have declared an emergency. In a K-ice plane, I could have waited a bit longer to make that decision.


Best,


Dave

 

[wsuffa]

We had just finished checking with Flight Watch as we had seen the build ups ahead and been told the tops were around FL180 and that an inversion was present; no uplifting action was specifically mentioned, but we asked the briefer if it would be better to climb or descend if we ran into ice: the briefer raised her voice and said whatever you do, don't climb, that's where the worst activity will be.

Dave

Dave, was that one of the same helpful Flight Watch briefers that sent you up over Little Rock on the way to Gaston's two years ago?

 

[Lance F]

This is one of those topics that recycles, and I am personally glad it does. My take, based on experience, is that ice in a non-KI aircraft is extemely dangerous. I don't think this can be over-reenforced.

I've posted my story before but to me it was quite instructive. It looked like a good April day in Atlanta area for some IMC practice: ceilings about 800', vis 5 miles+. The idea was to fly with an instructor about 40 miles to a towered field, shoot the ILS there a couple of times and then fly back to an NDB approach at my home field. We flew a 160hp C172. My official FSS briefing less than an hour before launch said no icing below 8000'

As we climbed from 3000 to the assigned 4000 in solid IMC, the temps started dropping kind of fast and sure enough we started picking up rime. Both parties on board started getting concerned as we were on a long downwind vector to the localizer. I wanted to ask for lower, but there was no getting a word in edgewise with Atlanta Center. I was concentrating 110% on flying the plane but there was a lot of nervousness in that cockpit. I only dared a quick look at the strut and main gear tire on my left. There was a lot of ice on them and the windscreen was totally iced over.

As we were being turned to intersect I was losing airspeed and couldn't hold altitude, but otherwise the plane handled ok. During the uncommanded descent and now on the localizer where it was ok to descend the ice started coming off, in some cases in pretty big pieces. By the time we broke out I could see through the windshield. Landed uneventfully w/o flaps and at a higher than normal airspeed. There was still plenty of ice on the plane.

It was probably good that I didn't look at the wings because the instructor told me the leading edges had built up a couple of inches of those horn looking things you see pictures of.

Took us two seconds to decide we weren't flying back to our home field that day.

Still scares me to think about it. Much longer in that stuff and that little 172 wouldn't have been flying any more. I keep my Mooney out of ice. Period.

As has been said above... ice is unpredictable. My advice...do not go into ice intentionally in a non-KI plane. Period.

 

[Greebo]

No offense Chuck, but the problem with this statement is that it has been done. It just isn't approved in the POH. True, the icing potential is an unknown, but the knowledge would still be helpful.

My guess is that my airplane has had ice on it before, I just haven't been around to see it. Maybe I just need a video of it.

I'm not offended, but I disagree that you can know the icing potential, because the potential for icing varies vastly depending on weather conditions. Thin clouds on a low humidity day at freezing temps can probably be trusted not to ice quickly - but what about high humidity days on days where the temp is dropping rapidly? How can you predict how fast the ice will accumulate.

You can't, as far as I know.

As a pilot, I'd rather limit the variables in my flight to what CAN be predicted at all possible times. You get less dead that way. And I can predict how much ice will build up only if I can keep the amount that will build up at 0.

 

[spiderweb]

Interesting. This post has become one of the best I've seen in awhile, with real hardcore aviation discussions. Even with my vote on the thread, it still only has two stars! Just goes to show you. . . .

And yes, I will continue to ask any question I want, without worry of star-rating. LOL!

 

[AirBaker]

You can't, as far as I know.

As a pilot, I'd rather limit the variables in my flight to what CAN be predicted at all possible times. You get less dead that way. And I can predict how much ice will build up only if I can keep the amount that will build up at 0.

I guess that is where the past experiences in icing comes into play.

You can keep that amount at zero... Just never fly in conditions even close to icing! As some of the stories have shown here, it does happen, even if it wasn't known icing.

Sorry... I'm trying to stop beating this horse...

 

[Dave Siciliano]

Dave, was that one of the same helpful Flight Watch briefers that sent you up over Little Rock on the way to Gaston's two years ago?

Uhh. You still remeber that, huh Bill. Thank goodness for the 396 now. Yes, IMO, this briefer was both inaccurate and out of bounds. I look at them being weather experts, not pilots. Just give me the facts (as Joe Friday used to say on Dragnet--Just the facts Maam!). She was giving opinions; don't do this or that. Didn't make sense to descend into colder air with an MEA I was close to the minimum on.

Dave

 

[Dave Siciliano]

This is one of those topics that recycles, and I am personally glad it does. My take, based on experience, is that ice in a non-KI aircraft is extemely dangerous. I don't think this can be over-reenforced.

I've posted my story before but to me it was quite instructive. It looked like a good April day in Atlanta area for some IMC practice: ceilings about 800', vis 5 miles+. The idea was to fly with an instructor about 40 miles to a towered field, shoot the ILS there a couple of times and then fly back to an NDB approach at my home field. We flew a 160hp C172. My official FSS briefing less than an hour before launch said no icing below 8000'

As we climbed from 3000 to the assigned 4000 in solid IMC, the temps started dropping kind of fast and sure enough we started picking up rime. Both parties on board started getting concerned as we were on a long downwind vector to the localizer. I wanted to ask for lower, but there was no getting a word in edgewise with Atlanta Center. I was concentrating 110% on flying the plane but there was a lot of nervousness in that cockpit. I only dared a quick look at the strut and main gear tire on my left. There was a lot of ice on them and the windscreen was totally iced over.

As we were being turned to intersect I was losing airspeed and couldn't hold altitude, but otherwise the plane handled ok. During the uncommanded descent and now on the localizer where it was ok to descend the ice started coming off, in some cases in pretty big pieces. By the time we broke out I could see through the windshield. Landed uneventfully w/o flaps and at a higher than normal airspeed. There was still plenty of ice on the plane.

It was probably good that I didn't look at the wings because the instructor told me the leading edges had built up a couple of inches of those horn looking things you see pictures of.

Took us two seconds to decide we weren't flying back to our home field that day.

Still scares me to think about it. Much longer in that stuff and that little 172 wouldn't have been flying any more. I keep my Mooney out of ice. Period.

As has been said above... ice is unpredictable. My advice...do not go into ice intentionally in a non-KI plane. Period.

Lance:

Don't want to knock a 172, but if I did get into icing conditions that would sure not be my first choice of planes to be in Not many options open othre than to turn around or make a descent. Couldn't climb much in that puppy if the ice accumulated much. Glad you're still around after that one!!

Dave

 

[Dave Siciliano]

Let's contrast flying the A-36 to the P-baron.

The Baron is fully booted, hot props has a hot plate, pitot, stall warning and fuel vent heat; ice light; antennas angled back to shed ice; alternative inlet air over the exhaust manifolds. Much more power--650 total v. 300 for the A-36 with a slightly better HP to weight ration. Much more stable platform. In this plane weekend before last, I challenged forecast icing conditions. Near zero C at my altitude; colder higher and lower. Inbetween layers. Short periods of time in the soup. Nexrad showed visible moisture. Radar showed low levels of precip. All icing reports were below us. Many reports of no ice at our level or above. The only icing PIREP near us was for a V-tail Bonanza (which we pretty much discounted as not being a K-ice aircraft).

Had we encounter more than light icing conditions, we could first turned west where the Nexrad and radar showed much lower levels of precip; climbed much higher where tops were in the low 20s or done a 180.

Probably wouldn't have done this in the A-36. If I couldn't get around it, above it or above freezing in the precip, would have stayed the night somewhere. The Baron let me challenge more likely conditions, and, in this case, I was able to continue home with little accumulation.

Dave

 

[SCCutler]

...and I read every one of these, hoping I learn all I ever know about ice from stories and publications.

Thanks, all, for posting.

 

[Ed Guthrie]

I think one of the problems is not knowing how your plane handles ice until you've got it. How much ice can it carry? Do you need to get out of it at the first sign of it?
(and)
While it would be great to see it in a k-ice plane, I'd want to know what my tolerances are. Just so I'm not misunderstood. I'm not going to go charging off into known icing. I'm not downplaying it's danger. I'm not looking to see exactly how much ice the Bo will carry.

Here's the short answer: There is no predicting ice accumulation rates. "Light" could in a blink of the eye become "severe" just as easily as "severe" could become CAVU. When we hit icing conditions we don't know what the next 10 seconds will bring even if we've been watching the same show for the past 20 minutes. Given that stark reality, and it is the reality, why do you care if your aircraft can handle 1/4" of ice or 5" of ice? You can't predict when the limit will be hit, so knowing the limit is useless trivia. IOW, "Do you need to get out of it at the first sign of it?" --- Absolutely! (and a few expletives I'll leave unwritten)

 

[Dave Siciliano]

Ed:

Since Ryan isn't on this Board, I'll step into his shoes for a minute and respectfully disagree. While I do agree with your general premise, there are times accumulation rates can reasonably be predicted. Of course, not in dramatically building systems, but there are times.

I've flown in stratus tops where the ceiling was very stable and the accumulation rate was very tame. Same thing in bottoms and in layers I could see through. You make an excellent point; there certainly are times the accumulation rate is completely unpredictable, but there are also times when rapid buildups are just not in the cards, but you know that. There are also times one can rapidly exit if there's a problem.

All that said, a C-172 isn't an aircraft I'd challenge much in.

In the TN A-36 I would take on a little more using Dr. Bruce's reasoning on having several outs. In the P-Baron, I'll take on a little more, but not rapidly building systems; large frontal systems (unless weak) or areas where there is rapidly rising warm air over cold air and I'm below.

This is an area where the exact circumstances must be measured, where experience and judgement make a difference as does the capability of the aircraft. Most of the GA aircraft the board members are flying here have very little tolerance to icing.

I am in agreement with your general advise, but you like to nit pic and seem to be missing your best counter point person

Dave

 

[gismo]

Don't let this happen:

looks like severe icing to me!

 

[Ed Guthrie]

While I do agree with your general premise, there are times accumulation rates can reasonably be predicted. Of course, not in dramatically building systems, but there are times.

While I understand and agree with your premise, for the record, a person who is asking "how much ice" has no clue what those predictable conditions would be nor what the range of variation within those predictable conditions might be. I'll stick with my advice, thank you.

 

[Dave Siciliano]

And I agreed with your "general" advise.

But still think I might have shut the other engine down with the winds that were given in the other post

 

[poadeleted20]

Ron, does FAA take the position that (visible moisture) + (forecast temp aloft of 0C to -40C) = automatic bust?

I don't think the temp range would be quite that inclusive, as the likelihood of icing drops significantly below -10C and very sharply below -20C, but their thinking doesn't seem to be far off that if circumstances bring a case to their attention.

The language in the Curtis decision ("[...] respondent should have known from the weather forecasts that there was a reasonable possibility he would encounter icing") seems to suggest it does.

No doubt that the forecast and reported conditions into which Curtis launched fit very squarely within those which most pubs suggest are highly conducive to icing.

I realize there was other evidence against Curtis (pireps, etc.), but this sounds like a new definition of what "is" is: "reasonable possibility" is the same as "known."

In Curtis' case, more like "high probability" than "reasonable possibility."

Likewise, does a "NO SIGNIF ICE EXP" comment in the weather briefing take it out of "known ice" category, assuming no pireps to the contrary?

Within certain limits, I would think so, but I'd keep in mind that visible moisture plus freezing temps generally equals structural ice, and if the OAT were -5C, I wouldn't fly into a cloud that had not been forecast to be there.

(Last year I flew from Portland to Seattle, forecast freezing level at 8,000 on the back side of a drying, dissipating front, "NO SIGNIF ICE EXP" in the briefing. I started picking up ice at 6,000, and got out of there quickly.)

You'd need more info to analyze this. What was the basis for the "NO SIGNIF ICE EXP"? Was the lowest cloud layer forecast to top out below the freezing level? Were no clouds forecast below the point where temps went below -20C or so? IOW, had conditions developed other than as originally forecast, and were the conditions which did develop of a sort that you should expect to be conducive to icing?

All that said, the FAA isn't out there checking to see who's flying on days when icing is likely. They pretty much rely on reports from ATC or accidents or other things like that. So if you don't have to declare an emergency to get out of predictable icing, and you don't crash with an ice-encrusted airplane, you're not likely to come to their attention (which is not to say you won't get snagged anyway, but it isn't likely). Nevertheless, it is a well-proven fact that even light icing can be lethal to aircraft not equipped for it, and even KI-certified aircraft may be brought down by icing that is forecast or reported as moderate to severe. Choose wisely.

 

[Richard]

WRT Dave's comments on accumulation rates knowing the type of wx (lift index, etc) is more important than knowing the airframe characteristics for picking up ice. A serious study of wx is a full time job.

I'm late to this thread so I apologize if this has already been covered, but WRT Chris' wanting to know how to tell the point of no return I'd say going from no ice to ice is the point. There has been a change (0 to >0) which indicates a trend. Is it gonna' get better? That's an unknown at that point. The question is not when but how to exit. Making a 180 is my best answer although in my only two icing events I made a descent into warmer. I don't fly KI a/c.

 

[AirBaker]

...why do you care if your aircraft can handle 1/4" of ice or 5" of ice? You

Ed, I think what you've said is good advice. My answer to the above is... I would not fly in IFR conditions even CLOSE to possible icing if my aircraft could only handle (figureatively) 1/4" of ice versus the 5"...

Knowing that I can handle 1/4" safely, gives me that chance to make the 180, ascend/descend, to get out of the ice. And to do so by choice.

 

[Greebo]

Here's the short answer: There is no predicting ice accumulation rates. "Light" could in a blink of the eye become "severe" just as easily as "severe" could become CAVU. When we hit icing conditions we don't know what the next 10 seconds will bring even if we've been watching the same show for the past 20 minutes. Given that stark reality, and it is the reality, why do you care if your aircraft can handle 1/4" of ice or 5" of ice? You can't predict when the limit will be hit, so knowing the limit is useless trivia. IOW, "Do you need to get out of it at the first sign of it?" --- Absolutely! (and a few expletives I'll leave unwritten)

Thanks Ed, that's my point exactly!

 

[gismo]

Instead, I continue to use forecast temperature soundings from the Rapid Update Cycle (RUC) model like the one below. This particular forecast tells me to expect freezing drizzle over KAMA. Along with the synoptic view, I can quickly assess the primary factors associated with icing which includes saturation (small dew point depressions) and slightly supercooled temperatures at any altitude and location in the US. This provides me with a much clearer picture of the usable and unusable altitudes along my route of flight. It is not always conclusive, but there are cases (as in the one below) where there's no doubt. I make sure all of my students (especially instrument students) get a good dose of training to recognize these very adverse events.

Scott, would you please explain what you mean by "small dew point depressions" and their significance here. Also from the RUC you posted would you agree that cruising at or above 10k MSL (700 mb) should be ice free even if there are clouds due to the lack of moisture (my guess would be that the cloud tops are lower anyway)? And finally, the soundings are great for analyzing departure and destination wx, but how do you go about interpolating in between for xc flight?

 

[Anthony]

Interesting. This post has become one of the best I've seen in awhile, with real hardcore aviation discussions. Even with my vote on the thread, it still only has two stars! Just goes to show you. . . .

Ben. Many of us forget about rep points and thread ratings, or we just don't give it much thought. This is an excellent thread! Thanks for initiating it as I have learned a lot.

 

[Pilawt]

All that said, the FAA isn't out there checking to see who's flying on days when icing is likely. They pretty much rely on reports from ATC or accidents or other things like that. So if you don't have to declare an emergency to get out of predictable icing, and you don't crash with an ice-encrusted airplane, you're not likely to come to their attention (which is not to say you won't get snagged anyway, but it isn't likely). Nevertheless, it is a well-proven fact that even light icing can be lethal to aircraft not equipped for it, and even KI-certified aircraft may be brought down by icing that is forecast or reported as moderate to severe. Choose wisely.

Good analysis, Ron. Thanks.
-- Pilawt

 

[Dave Siciliano]

Scott:

Any way you can look at what was going on Sunday before last over southern Missouri and northern Arkansas about 5:00 P.M.? That's what I flew through at 12,000 feet. Would love to have your perspective on what should have been there!

Dave