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.

"BDS" wrote in message
m...
"Gary Drescher" wrote

Yup, legality and safety are not synonymous. Still, I think it would be
safe
to fly IFR through a thin cloud layer (with plenty of room above and
below)
even if there's a forecast for occasional moderate icing in clouds. And
according to the AIM's current definition of "known icing conditions",
that
would be legal (for Part 91), as long as there are no PIREPs that confirm
the forecast.

Section 91.527: Operating in icing conditions.

Heh, I mistakenly quoted the same reg earlier in this thread. As was
quickly pointed out, that section of the regs applies only to large or
turbine powered planes, not to the planes that most of us fly.

--Gary

"Doug" wrote in message
oups.com...
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 according to the FAA's definition of "known icing conditions" in the
current AIM (which I quoted and linked to a few messages ago in this
thread), a forecast of icing definitely does *not* count as "known icing
conditions". And the only ice-related prohibition I'm aware of in the POH of
typical small planes is phrased in terms of known icing conditions (not
forecast icing conditions).

--Gary

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.

How do you know how good a judge of ice that anonymous pilot who's
flying a different kind of plane than you is?

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.

Well, is it 30% of picking up ice (but it would be everywhere) or there
is ice in 30% of the cloud? And which way is out?

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.

wrote:
In rec.aviation.ifr Matt Whiting wrote:
: This has certainly been my experience also. I recently flew from
: Lebanon, NH to ELM on a day with the freezing level around 4,000 and an
: MEA of 6,000 across the mountains of southern VT. I picked up some
: light rime and requested higher and got between layers. The clouds
: again arose to smite me, so I requested higher again and broke out on
: top at 10,000. My requests were calm and matter of fact and the
: controllers were extremely accomodating. There was never even a hint
: that they questioned why I was flying an Arrow on such a day.

Because you didn't have a problem, they don't have a problem. If you had
*had* a problem, they would have found this problem and busted you. Isn't it great?

Maybe, but I really doubt it unless my problem resulted in an accident
or maybe a "deal" for the controller if I had to make a descent that
they couldn't clear quickly enough. Even though I've flown in northeast
winters for 28 years and tend to "take a look" even if icing is a
possibility, I've only once ever gotten into anything I'd call trouble.
Even then, I didn't need to declare, I just needed a block altitude
clearance so I could descend until I could maintain altitude.
Fortunately, I reached the equilibrium altitude prior to reaching ground
elevation. :-)


Matt

Gary Drescher wrote:

"Bob Gardner" wrote in message
. ..

As George said, in Adminstrator vs Bowen, in 1974, the Administrative Law
Judge said, more or less, "known does not mean a near-certainty of icing
conditions, only that icing conditions are being reported or forecast."


But that 1974 decision is at odds with the current AIM, which defines
various icing conditions in section 7-1-23
(http://www.faa.gov/atpubs/aim/Chap7/aim0701.html#7-1-23):

"Forecast Icing Conditions--Environmental conditions expected by a National
Weather Service or an FAA-approved weather provider to be conducive to the
formation of in-flight icing on aircraft."

"Known Icing Conditions--Atmospheric conditions in which the formation of
ice is observed or detected in flight."

So according to the AIM, forecast icing is not tantamount to known icing.
Rather, only a PIREP of icing (or a pilot's own observation in flight)
constitutes known icing.

Although the AIM isn't regulatory, it does purport to furnish information
that is relevant to a pilot's understanding of FAA regulations. So when the
latest AIM defines a term that the FARs use but don't define, it would
violate due process to expect pilots to know and use some other definition
instead. (Does anyone know if the current AIM definitions were present back
when the previous rulings on known vs. forecast icing conditions were
issued?)

Gary, Gary, Gary. You are trying to apply logic to government
regulations and the agencies that write and interpret them. This is a
lost cause. :-)


Matt

The one I like is: is it "known........ icing conditions" or is it
"known icing.........conditions".
(It doesn't matter, but it's confusing enough to throw the guy off
track while he TRIES to understand the difference)

On Wed, 14 Dec 2005 16:33:31 GMT, George Patterson
wrote:

John Doe wrote:

1) If the cloud layer is forecast to potentially have icing, can you legally
and would you climb through the layer to get up high for your trip? how
thick a layer, type of forecast, time spent in the layer, etc. What would
you be willing to risk transition through possible icing?

No. Legally, forecast ice is "known icing."

A bit of a distortion.
The phrase in the regulations is "known icing conditions". A forecast that
mentions icing satisfies this as the conditions (leading to potential) icing
are indeed known -- if you have read the forecast -- and you are required by
regulations to obtain all relevant information for the flight which includes
a weather forecast.

Many pilots try to parse the requirement as "known-icing conditions" whereas
the FAA has defined it to mean "known icing-conditions" -- a subtle but
inportant difference when it comes to defending oneself against a
certificate action. A forecast of icing constitutes "known
icing-conditions."

4) Let's say yoru trip starts off VFR but by the time you get to your
destination, a cloud layer has formed that has reported icing in it. Can or
or would you be willing to transit this layer to land at this destionation
or would you turn around or divert to land someplace to stay out of the
clouds?

If I want to stay VFR, I won't be transiting any clouds. Being unwilling to risk
a violation if I file IFR and then fly through reported icing, I would divert.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.

--
Jay.
(remove dashes for legal email address)

Bob Gardner wrote:

Gary, the most recent case was in 2005. That's what George was linking to.

No, that's the date of the article. The most recent ruling on the forecast icing
issue was about 12 years ago. There were earlier ones as well. If, however, the
AIM is in conflict with case law (and it is), the AIM is wrong.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.

"George Patterson" wrote in message
news:_Qpof.17301$Jz6.14963@trnddc06...
Bob Gardner wrote:

Gary, the most recent case was in 2005. That's what George was linking
to.

No, that's the date of the article. The most recent ruling on the forecast
icing issue was about 12 years ago. There were earlier ones as well. If,
however, the AIM is in conflict with case law (and it is), the AIM is
wrong.

The AIM presents the FAA's current official definition of "known icing
conditions". So any case law decided on the basis of prior explicit or
implicit definitions is no longer applicable.

--Gary