Flying through known or forecast icing

The situation seems to be, for part 91 ops, that if it is forecast,
that is if there is an AIRMET for icing (AIRMET ZULU), then it's not
legal to fly in it without approved deice equipment. But.....no one
enforces it (for part 91), and it is known that part 91 aircraft do fly
in it (by ATC), and so long as you don't declare an emergency or crash,
I don't think there has ever been a citation for it.

Having said that, I don't think its a very good idea to launch with
airmet ZULU along your route, but there may be some exceptions (like
when you have VFR beneath you above the MEA), or you have a pilot
report from a pilot who was just in it and not only didn't he pick up
ice, but he doesn't think there IS icing in those clouds. Also,
decending through a thin layer of rime (like 1000' thick) and it is
known that you wont get ENOUGH ice to affect your aircraft.

Statistically, its not a big problem. There aren't that many crashes
due to icing (there are some), but that doesn't mean its safe, just
that pilots are handling the hazard (usually by not flying in it).

But the fact that part 91 aircraft do it, and don't crash, doesn't make
it legal. Just makes it that they are getting away with it.

I think they should make icing a "percent probability" and when the
probability is greater than some figure (say 30%) then it's a no go.
This would allow them to given the 30% icing figure indicating ice, but
keep it at 30% indicating there is VFR under it or that the layer is so
thin, it is not likely to cause problems.

What you really want to aviod is being trapped in it with no VFR under
you, no ablity to outclimb it, and no way to turn around (although its
hard to imagine NOT being able to turn around, fuel, I guess).

Anyway, talk to pilots who have picked up ice and you will get the idea
that it is not, in general , a good idea. In fact, avoid it. That is
what I do.