Lingering in icing

[hais]

Why is that bad?

A. Likelihood of encountering severe icing?

B. Eventually your FIKI will be overwhelmed even if the conditions do not change?

C. Not tested as part of certification?

D. Other reason?

[Pinecone]

Why would you want to linger in icing???????????

[hais]

1 hour ago, Pinecone said:

Why would you want to linger in icing???????????

I'm trying to understand which one of the above is the reason as to why that's a bad idea.

[larrynimmo]

Ice builds up to the point that the plane gets too heavy, and you lose aerodynamic lift…

essentually you will stop flying 

[N201MKTurbo]

There is a lot to consider. The weather mostly. Remember you are depending on a non-redundant system. If it quits, can you get out of the ice, or land before the ice is a problem? What is the rate of accumulation? Is it consistent or variable? 
 

I would use the anti- icing to find an altitude with no or very little accumulation instead of flying constantly at an altitude where it is accumulating ice. 

[N201MKTurbo]

The worst thing I ever had to do with ice was landing with an iced over windshield. The only view of the outside world is through the little window. That’s kind of weird.

[irishpilot]

Icing isn't always predictable and what is forecast to be light or moderate icing, can turn severe pretty quick. Clear ice can build rapidly and depending on conditions, a pilot can't escape. With icing, you have four options: 1) keep flying in it, 2) descend, 3) climb, or 4) turn around.

Environmentals will drive what is possible, and a pilot's ability to interpret real-time info will raise the success of choosing the right option.

Lastly, if you don't have experience with icing, keep your GO/NO GO decisions very conservative and turn around if you get into unexpected icing and don't know how large the area is. With my Bravo I never planned to fly into known icing, and used it when temps dropped within range. TKS must be used preemptively vs reactively like boots.

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[M20F]

Always assume something is going to break.  I generally try to find VMC for the same reasons.  Much better to be 2kts slower 2000ft above a layer than 2kts faster in it. 
 

[Fly Boomer]

7 hours ago, hais said:

Why is that bad?

Also, there is SLD ice which can overwhelm your ice protection pretty quickly:

https://www.ctsys.com/sld-icing-avoid-avoid-avoid/

[Ragsf15e]

Define “lingering”…. 
I don’t plan to cruise in it.  Look for clear air or -20c or colder air so that you’ll be out of icing conditions in cruise.  However, there’s times during descent and vectors to approach where you’ll have to “linger”.  The TKS should already be on, you should have pireps and forecasts, and you should have an out option planned - up, down, turn around?  You’ll need to assess type and rate of accumulation and decide if you can continue with the approach sequence or tell the controller what you need to do different.  Just because you’re picking up light rime during radar vectors to final (say on downwind) doesn’t mean you need an emergency climb out of it and divert.  The tks keeps the flying surfaces pretty clear when used properly, working correctly, and not moderate+.

[Fly Boomer]

25 minutes ago, Ragsf15e said:

The tks keeps the flying surfaces pretty clear when used properly, working correctly, and not moderate+.

Best summary I have seen.

[Fly Boomer]

27 minutes ago, Ragsf15e said:

you should have an out option planned - up, down, turn around

Nice, succinct list of options.

[Marauder]

Icing isn't always predictable and what is forecast to be light or moderate icing, can turn severe pretty quick. Clear ice can build rapidly and depending on conditions, a pilot can't escape. With icing, you have four options: 1) keep flying in it, 2) descend, 3) climb, or 4) turn around.

Environmentals will drive what is possible, and a pilot's ability to interpret real-time info will raise the success of choosing the right option.

Lastly, if you don't have experience with icing, keep your GO/NO GO decisions very conservative and turn around if you get into unexpected icing and don't know how large the area is. With my Bravo I never planned to fly into known icing, and used it when temps dropped within range. TKS must be used preemptively vs reactively like boots.

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^^ This. I remember flying back to my home base in Buffalo years ago. I was on a Victor airway with a Cherokee ahead of me and at the same altitude. The next thing I heard was the guy in the Piper declaring an emergency and saying he couldn’t maintain altitude. When queried by the controller he said he was instantly iced over. He made it out of the icing and landed at a nearby airport.

So, there I am wondering if I am going to run into the same stuff. I was young and dumb and as most young and dumb pilots, decided that “if he got out, my superior piloting skills and my trusty Mooney steed could handle it”. I flew into the same area and picked up absolutely nothing. Then on a flight a few weeks later, I picked enough icing in a thin stratus layer I was climbing through that made me older and smarter.

The point is that icing is unpredictable. I learned you don’t linger in the clouds in the winter, especially in places like Buffalo. You also become more of a student of weather to understand the Skew-t and available info from sources like ADDS. And I’m sure the guys flying the known ice planes are still cautious about any icing since they can still encounter stuff like SLD that can overwhelm an anti-icing system on our class of plane.


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[kortopates]

2 hours ago, Marauder said:

The point is that icing is unpredictable. 
 

The #1 thing to understand is what Chris says above and how unpredictable includes the highly variability of icing conditions you can encounter. Icing is not at all uninformedly distributed since the water content in clouds can be highly variable. As Chris described, even Pireps a few minutes ago may not be indicative of the conditions you'll encounter due to the highly variable nature. The insidious aspect of icing is that you have no idea whether you could be only a few minutes away from not being able to maintain altitude from getting an instantaneous coating of thick ice and heading down. Way too many dead pilots that waited too long before attempting an exit strategy only to find themselves in worse conditions and loosing control.

Although its been mentioned options are turn around, climb or descend; you really only have the options your pre-flight planning planned for to include and that your equipment allows. For example climbing is not generally a realistic option in NA aircraft, nor is turning around after the pilot "lingered" in it for too long, leaving only down that may not have an airport to reach before finding terrain.

Some excellent ground training on icing is available here: https://aircrafticing.grc.nasa.gov/  

[jaylw314]

10 hours ago, hais said:

I'm trying to understand which one of the above is the reason as to why that's a bad idea.

The only time icing causes problem instantaneously is if you get hit by hailstones.

Otherwise, problems from structural icing always requires icing + time.  The problem is, you don't know if it could be seconds, minutes or hours.

So "lingering" is asking for trouble, because you're giving it the 'time' part of the equation.  If you never give it enough time, you'll never get run into problems.

[Danb]

Chris mentioned icing in Buffalo,Johnny Z North Dakota, icing knows moisture and temperature. I encountered nasty icing conditions in the summer the las test was last month. Many icing encounters in the summer seems to be clear and or mixed ice as the top of the cumulus clouds hold the most moisture. Be cognizant all year round when determining the potential for ice. Mine weren’t forecast nor had notams, other than the ones I left. When climbing over or trying to stay on top me wary of the outside temps. They drop quite a bit while your busy trying to stay clear of storms. Learning skew t log is of tremendous help in the summer for icing, clouds turbulence etc.

 

[hais]

Looks like everyone agrees it is because one might encounter severe conditions. 

Assuming your equipment doesn't fail : what happens to unprotected surfaces after a "very long exposure" : will the airplane accumulate enough weight to cause drag/weight problems? 

To clarify: this question is not geared towards decision making or planning. It is geared towards understanding the mechanics of what happens.

[Fly Boomer]

10 minutes ago, hais said:

will the airplane accumulate enough weight to cause drag/weight problems? 

Tail stall.  Lawn dart.

[kortopates]

see the Nasa icing course above.
you were also tested on this in both the private pilot and instrument written exams.


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[Danb]

As Paul mentioned it involves all four forces of flight are compromised negatively. Increased drag, reduced lift, increased weight reduced thrust. 
 

 

[Ragsf15e]

Well to be fair, he said “unprotected surfaces”. The TKS can keep light icing clear on protected surfaces.  So the prop and wings in general stay clean.  In fact, in light (and moderate) icing almost all accumulation is on leading edges of wings, prop, and windshield which are all protected.  

Now I’m not advocating sitting in icing indefinitely, but without moderate + icing and enough time to overcome the system, she’s not going to fall out of the sky.

Watch the nasa video or just look at where tks/boots are.  Icing forms on leading edges.  As it gets to moderate or severe or sld, it starts to form further aft on the wings and that’s obviously bad.

I guess what I’ve seen is it depends on severity.  In light icing on an unprotected surface (say the cowling), I don’t see ice adhere there.  In stronger ice, all bets are off.

[kortopates]

FIKI means it’s approved for flight in known ice. To be certified, they had to demonstrate the plane could handle upto and including moderate icing pretty much indefinitely as long as you still had TKS fluid. There isn’t much left over that can accumulate ice that’s unprotected save for wing tip lights and antenna’s; neither of which would bring you down. But several have loss COM from shedding iced up COM antenna’s.


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[hais]

2 minutes ago, kortopates said:

FIKI means it’s approved for flight in known ice. To be certified, they had to demonstrate the plane could handle upto and including moderate icing pretty much indefinitely as long as you still had TKS fluid. There isn’t much left over that can accumulate ice that’s unprotected save for wing tip lights and antenna’s; neither of which would bring you down. But several have loss COM from shedding iced up COM antenna’s.


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I might be mistaken, but I thought the limit was 45 minutes - which is what got me thinking in the first place what happens.

I was wondering whether it is known what happens beyond the limit or whether the limit was set in the spirit of providing sufficient time to escape but without establishing what happens after.

[Ragsf15e]

26 minutes ago, hais said:

I might be mistaken, but I thought the limit was 45 minutes - which is what got me thinking in the first place what happens.

I was wondering whether it is known what happens beyond the limit or whether the limit was set in the spirit of providing sufficient time to escape but without establishing what happens after.

What you start noticing is a reduction in climb rate or cruise speed depending on whether you’re climbing or in cruise.  As folks noted above, it happens pretty fast.  I’ve seen a significant climb reduction before in a turboprop with boots.  If taken further I would have had to put the nose down to preserve airspeed, descend to warm air and divert.  If I didnt have a good out (down to warm air) in that case I would have been in real trouble.  As it was, it wasn’t comfortable.  There was a good amount of ice on after climbing through the tops.

[hais]

11 minutes ago, Ragsf15e said:

What you start noticing is a reduction in climb rate or cruise speed depending on whether you’re climbing or in cruise.  As folks noted above, it happens pretty fast.  I’ve seen a significant climb reduction before in a turboprop with boots.  If taken further I would have had to put the nose down to preserve airspeed, descend to warm air and divert.  If I didnt have a good out (down to warm air) in that case I would have been in real trouble.  As it was, it wasn’t comfortable.  There was a good amount of ice on after climbing through the tops.

So, if I assume critical surfaces are ice free, I can compute for a given airspeed how long it will take for unprotected surfaces to accumulate enough to exceed available lift. This gets complicated quickly: assuming the ice doesn't break off due to wind/own weight, we'll have non-linear rate of accumulation...