Got ice?

[Ian_Wannabe]

Hey guys - Just thought i'd post a little tip that I was told today by my instructor that might help out other student pilots like myself....

Today we were forced down to 1,000ft due to the cloud base dropping quite quickly and so quite obviously, icing became more of a risk as we're flying close to the cloud...

My instructor told me this bit of advice:

"When you're flying close to the cloud keep looking at your wheels. On the C150 I fly its apparent that you can see the ice forming on the wheels before the airframe. It's also quite easy to see as white on black stands out".

If this is a well known tip .. my appoligies, just as a student pilot myself I wasn't aware of it until today and so I thought i'd share as it might save someones life one day

Regards,

Ian

[DFC]

I think that there are two issues here that you need to consider;

1. Airframe ice will form when flying in actual icing conditions. That means in the case you describe you would have to be in the cloud unless it was raining and the OAT would have to be 0 or below (can happen a few deg above 0 so icing conditions are often defined as OAT less than +5 and visible moisture).

2. Ice will form best on objects with small radius facing into the airstream. That means in order of first to last to show icing;

OAT probe or similar (not on the C150 as it is in the air vent)
Strut
Tail
Wing
and some where down the list, the tyre.

So if you were below the cloud and it was not raining it is very unlikely that you would pick up any icing no matter how cold it is.

Having said all that, with the high moisture content of the air close to the cloud base, you could expect a lot of Carb icing at all power settings.

Regards,

DFC

[proprpm]

Great Hint but not much good in a PA28 :D . Good Luck with your flying . I am stuck on the ground due to the crosswind:{ .

[FlyingForFun]

Great Hint but not much good in a PA28 True, but DFC's list of places ice forms is ideal for a PA28 - in my limited experience (I tend to stay out of icing conditions in aicraft which aren't certified for it ;)) ice always forms on the OAT sensor first in a PA28. I couldn't comment on the next place after that, because I've never hung around long enough to find out!

FFF
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[Fuji Abound]

Icing is not relevant to a PPL. Whilst your instructors comments may be interesting or may have been a “throw away comment” you should not take any comfort from his comments.

Why?

As others have said icing will essentially only occur in cloud or air with sufficient moisture that flying conditions will no longer be visual. Without wishing to be dramatic that is no place for a PPL to be - ever. Should you ever find yourself in those conditions of far far greater concern will be keeping the aircraft level and getting out of the cloud as quickly as possible. Without wishing to be too dramatic, I suspect if you are not clear of cloud before icing becomes an issue it will already be too late for other reasons than the ice!

If on the other hand you are instrument trained the problem with comments such as this is there extreme generalisation. I recall a “little” icing in some wet clouds. On entering the cloud the screen froze over white within 30 seconds, forget watching the wheels or anything else for that matter.

The bottom line is with a PPL never go into cloud freezing or otherwise - ever!

[englishal]

As others have said icing will essentially only occur in cloud or air with sufficient moisture that flying conditions will no longer be visual. Without wishing to be dramatic that is no place for a PPL to be - ever
Hmm....not strictly correct. I used to hold a PPL and IR and would regularly fly in cloud. It is worth considering that when the MEA is up to 11,000', you may get icing even in sunny climes like California....

But I know what you're saying ;)

[Ian_Wannabe]

Mmmm thanks for the replies everyone. Seems like I made a sweeping generalisation that i'm glad has been cleared up on here.

Just to add - I wasnt too specific to the conditions and as mentioned we were not actually in cloud, just below the base and yes, we had precipitation of the snow kind and therefore my instructor passed this comment on.

Although you're all totally correct and I have no place or experience to speak over you I can't help feeling that being aware that you will be able to see ice forming on the tyre (be it after the airframe) that its something to keep in the back of your mind? Afterall, every little helps?

I cant speak from experience but how easy it is to see ice forming on a strut with little distinguishing coloured background?

Any thoughts?

[drauk]

Take a look here: http://www.dadams.dsc.net/flying/wca/photos/index.html
Scroll down and on the left hand side there is a picture of ice forming - click to enlarge it. As you'll see, on such a small protrusion (where, as others have said, the ice forms first) the ice is clearly visible because it changes the shape of the structure. Tougher in the dark or if your windows are frozen over, but if your windows have frozen over you can get bet you'll have ice elsewhere.

[boomerangben]

If you ever get a chance to get up close and personal with an S61, you will notice a black dot on the nose of each sponson. It's there for exactly the reasons you mention, although it is not the only means of checking for ice on that aircraft.

[Yorks.ppl]

I may be wide of the mark here but I would guess that the tyre would be one of the last places that ice would form, mainly because of it being made of rubber, which is a significantly better insulator than the metal of the airframe. I would therefore think that it would retain its temperature above freezing marginally longer than the wing, for instance.

Also it being black, and therefore more able to absorb heat, it would perhaps be at a slightly higher temperature than the white parts of the plane to start with.

Just my musings.

[Fuji Abound]

Interesting musings but I think the point here is that there are certain parts of the aircraft directly facing into the air flow. Whilst you are quite correctl that rubber is a good insulator and being black would also absorb any radiant heat these are of insignificant consequence compared with an airstream passing over the surface at 80+ knots at less than freezing. Any residual heat will be lost very very quickly and of course in cloud there is not likely to be much radiant heat around. :)

Boots as you will know are rubber and in the "right" conditions accumulate ice and a significant rate.

[strafer]

I was told that the first place you'd spot ice on a PA28 was on the front of the fuel cap ridge.

Never had it happen myself as I only like to see ice in my Vodka Red Bull.

[Fuji Abound]

Strafer

That would make sense. Ice forms most readily in the low pressure boundary around a radii facing the airflow. The evidence also indicates that the smaller the radii the more readily the ice forms. That is why ice often forms on aerials more quickly and the deposit is greater that on the wing for example. The fuel cap of course has exactly this type of radii relative to the air flow.

Interestingly that also makes one wonder whether Wannabe's instructor was ever correct in the first place. I would guess the radii of the wheels is greater than the wing or at least no less?

Another myth maybe?? Doenst aviation seem so full of them. I often wonder why??

[High Wing Drifter]

I was told that the first place you'd spot ice on a PA28 was on the front of the fuel cap ridge.
Would I be correct in summising that you might expect the not so dangerous (but I wouldn't try it) rime ice collecting on those kinds of surfaces. The clear ice (the lethal stuff) would need room to runback before forming. If so could it be a false indication in the sense that no ice on the cap (or any narrow edge) doesn't mean an ice free wing?

[strafer]

You may well be right HWD, which is why you should put your trust in the actual meteorological conditions rather than anything I say!:ok:

[Fuji Abound]

"The clear ice (the lethal stuff)"

Another myth - they keep on coming.

There are three forms of ice, rime, clear and mixed.

Clear ice is argueably the most dangerous. It weighs almost as much as the same volume of water, and builds very rapidly. It is also more difficult to remove with boots, but since the average SEP does not have boots this is irrelevant.

However, rime ice and mixed ice will weigh almost as much. Only one inch of ice will add nearly 200 lbs to the weight of a typical single. The aerofoil shape will change in an unpredicable way.

In short any ice is lethal, clear ice may just be lethal more quickly :confused:


"The clear ice (the lethal stuff) would need room to runback before forming"

Why?

[High Wing Drifter]

Strafer,
You may well be right HWD, which is why you should put your trust in the actual meteorological conditions rather than anything I say!
I guess I'm asking too. My understanding is that for clear ice to form, a portion of the supercooled droplet melts as a result of the release of latent heat and runs back then refreezes. I'm just concluding that on narrow edges, this won't be particuarly noticable compared to the amount hitting, melting, running back and freezing on the wing. Whereas rime would just freeze instantly and collect more readily on such edges.

[Them thar hills]

Ian
This may be a bit off-topic but if I found myself in a low cloud base situation as described, I'd be much more interested in looking out for any other traffic who may also be scratching along (especially if he were interested in his wheels)
TTH

[ShyTorque]

"There are three forms of ice, rime, clear and mixed."

Actually, there are four types. The ice building up on a wheel may, in extreme cases, prevent the wheel from turning on landing, very dangerous.

It's called chock-ice. :E

Sorry, just trying to cheer myself up.. :)

[Fuji Abound]

Made by Walls?

Sorry - a weird sense of humour.

[Yorks.ppl]

Further to my recent musings on this thread, I now retract what I proposed regarding tyres being possibly less likely to ice up than the metal structure.

Following friday afternoons blizard I can confirm that the tyres on my parked car were thick with snow, more so in fact than the metal parts of the body close by.

So it seems my theory is complete b****cks:O

Sorry.