PPRuNe Forums - View Single Post - SE IR during winter time and icing conditons
Old 8th Nov 2007, 20:46
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IO540
 
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In your case Fladbrokeandbusted I would stick to VMC.

If potentially going into IMC I would want the 0C level to be at least 1000ft above the MSA.

But as I said thin stratus is normally fine. I've often gone into the stuff to see how much ice I can pick up (having the obvious escape route of 0C level well above the MSA) and most of the time there is so little (after say 10 mins) one has to look carefully to see it. And I am doing only 150kt; aerodynamic heating at 150kt is only about 3C so not significant. So climbing up through it should be fine.

A key point is that no plane can fly in icing indefinitely. Not even a 747. The name of the game is always to make it a transient condition, and de-ice kit will help with that.

The most effective anti-ice equipment currently available (for non-jets) is full TKS, but the fluid container will last only an hour or two.

There is a class of pilots out there who fly in virtually all conditions. They are happy to sit in an Aztec for hours, with inches of ice hanging off it. They usually don't carry oxygen so they have no choice anyway. One should not criticise these pilots because, in the right plane and with the right experience, they don't actually get killed. But it is not the way to go about things, IMHO.

Jets get around it by having good anti ice equipment, climbing and descending fast, and flying fast. At 250kt TAS, airframe heating is around 10C and given that supercooled water will exist (in stratus) only between 0C and about -15C, if your airframe is heated by 10C then the thickness of the "icing band" shrinks from 15C (say 7500ft) to 5C (say 2500ft). At 300kt+ TAS you won't get any ice at all...

Even on a piston plane, there is a noticeable difference in ice accumulation rates between climbing at 90kt and descending at 170kt.

For background, here is a good NASA icing course.

A good article on freezing rain (the ultimate hazard) is here.
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