FAR 91.157 Operating in icing conditions

Matthew S. Whiting wrote:
O. Sami Saydjari wrote:

...snip...

It says "...no pilot may fly--
(1) Under IFR into konwn or forecast moderate icing conditions; or
(2) Under VFR into known light or moderate icing conditions..."

This seems odd. Why do you suppose the standards are different for
IFR and VFR ("moderate" vs "light or moderate)? Icing affects a
pilots ability to control the aircraft, so I do not see how instrument
training allows one to venture into worse conditions.


Well, I make no claim to understand that minds of the FAR writers, but
here's my opinion. It is more likely to inadvertantly encounter icing
when flying IFR in IMC. Pretty hard to accumulate ice if you aren't
flying in visible moisture (clouds or precip), so if you are VFR you
really have no excuse to get into even light icing conditions. ... snip...


You can easily be in VMC, ceiling 2000 feet, visibility 3 miles, and be
flying in freezing rain.

Ron Natalie wrote:
"Matthew S. Whiting" wrote in message ...


If the forecast icing isn't all the way to the ground, why isn't it
legal to file and fly below the clouds and the altitudes with forecast
or known icing?


Don't ask me, I didn't write the regulation. Presumably because they have not
put in procedures into the IFR rules to handle, IFR but remain clear of IMC.
They presume that if you are operating IFR you are prepared to enter IMC at any
time.



Is this a change in the last five years since I was flying actively?
Prior to that, this was common practice in the northeast. Otherwise, as
I said earlier, light aircraft would essentially be barred from filing
IFR for much of the winter months.


Matt

David Megginson wrote:
Bob Gardner wrote:

We have an *authorized procedure* out here in the Pacific Northwest,
developed by the FSDO Aviation Safety Manager and the folks at the
TRACON,
specifically for use when icing conditions are forecast. It is called
"Radar
Vectors for Ice" and involves vectors to climb away from the Cascades
until
high enough to be well above the freezing level or in the clear.
Obviously,
since this procedure was developed by the FAA and published in the Safety
Program newsletter every year at this time, a forecast of icing
conditions
is not, in and of itself, a bar to flight.


Of course not -- airspace is three-dimensional. I don't cancel a flight
planned for 4000 ft in the summer because there's icing forecast from
15,000 to 20,000 ft. I wonder if there is anyone in this group who is
seriously arguing that I should cancel such a flight.

Ron Natalie just said that.


Matt

Barry wrote:
It's illegal for him to operate IFR period.

Really? Even if you don't fly in the clouds?


If he is in a case where that reg applies to him, yes. The rules don't
say "in clouds" they say Instrument Flight Rules.


I think that all the icing forecasts I've seen say ICGICIP (icing in clouds
and in precipitation), so if you stay out of the clouds and precip there's no
forecast icing.

Barry



That was my understanding, but I've been inactive the last five years so
I was wondering if things had changed. I've made many a safe winter IFR
flight when icing was forecast, or even known, at some place at some
altitude range.


Matt

Icebound wrote:
Matthew S. Whiting wrote:

O. Sami Saydjari wrote:

...snip...

It says "...no pilot may fly--
(1) Under IFR into konwn or forecast moderate icing conditions; or
(2) Under VFR into known light or moderate icing conditions..."

This seems odd. Why do you suppose the standards are different for
IFR and VFR ("moderate" vs "light or moderate)? Icing affects a
pilots ability to control the aircraft, so I do not see how
instrument training allows one to venture into worse conditions.



Well, I make no claim to understand that minds of the FAR writers, but
here's my opinion. It is more likely to inadvertantly encounter icing
when flying IFR in IMC. Pretty hard to accumulate ice if you aren't
flying in visible moisture (clouds or precip), so if you are VFR you
really have no excuse to get into even light icing conditions. ...
snip...



You can easily be in VMC, ceiling 2000 feet, visibility 3 miles, and be
flying in freezing rain.



That's right. What part of "visible moisture (clouds or PRECIP)" didn't
you understand?

As soon as you see the rain, you should divert. Hopefully, before you
enter it too far. Typically, I can see rain shafts when flying in VMC,
unless if is really marginal VMC. Even if I can't see the rain before I
enter it, I can see it pretty quickly on the windshield and make a quick
180.


Matt

On Mon, 01 Dec 2003 17:38:24 GMT, "Matthew S. Whiting"
wrote:

If the forecast icing isn't all the way to the ground, why isn't it
legal to file and fly below the clouds and the altitudes with forecast
or known icing?


It is.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

On Mon, 01 Dec 2003 21:22:44 GMT, "Matthew S. Whiting"
wrote:

Is this a change in the last five years since I was flying actively?
Prior to that, this was common practice in the northeast. Otherwise, as
I said earlier, light aircraft would essentially be barred from filing
IFR for much of the winter months.


There's no change. Don't forget the regulation we've been discussing
applies only to Large and Turbine-Powered Multiengine Airplanes.


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

There was a change in the last five? years.

There are two things under discussion - the "large and turbine" reg, and the
"spam can" default reg.

Spam cans are now (this is a change) forbidden to enter FORECAST icing - that
is, "forecast" icing is now considered "known icing". This is a change.

I don't fly large and turbine powered aircraft, so don't know if that reg has
changed.

Jose

--
(for Email, make the obvious changes in my address)

"Matthew S. Whiting" wrote in message ...

Is this a change in the last five years since I was flying actively?
Prior to that, this was common practice in the northeast. Otherwise, as
I said earlier, light aircraft would essentially be barred from filing
IFR for much of the winter months.

The rule quoted has nothign to do with light non-turbine powered aircraft.

"Matthew S. Whiting" wrote in message ...


Ron Natalie just said that.


I did not. I said that 91.527 didn't differentiate between IFR in VMC and IFR in IMC.