Gary Drescher wrote:
"Matthew S. Whiting" wrote in message
...

Gary Drescher wrote:

"Matthew S. Whiting" wrote in message
...
Are there really any AOMs that refer to "known icing"? The Cessna

152/172

AOMs I've seen prohibit flight in "known icing conditions". That's most
plausibly parsed as known icing-conditions, that is, known conditions

that

are conducive to icing. So the icing itself doesn't have to be known,

just

the conditions. And a forecast tells you of those conditions.

Well, I have no idea what Cessna was thinking or intending when they
wrote that,


They could certainly have stated it more clearly, I agree.


but, I'd interpret it as known - icing conditions. I don't
think parsing it your way is at all the most plausible. It is like
saying not to land if it conditions exist that might cause a crosswind
in excess of the demonstrated crosswind.


It *would* be like saying that if the AOM's demonstrated-crosswind statement
were a limitation (it's not, at least for 152s and 172s) and, more to the
point, if it were stated as a prohibition against flying in "known
excessive-crosswind conditions". Presumably, the other AOM limitations are
not stated that way precisely because they would then have the wrong
meaning.


We worry about the actual
crosswind, not what might exist. To me, it is much more plausible that
they would be consistent with all such limitations and apply them to
actual prevailing circumstances, not based on conditions which might
lead to such circumstances.


First, the very fact that they phrase the icing limitation differently than
other limitations strongly suggests that they intend something different for
that one. Second, it's not at all plausible to have a "consistent" response
to very different sorts of circumstances. There's no reason to prohibit
landing in conditions that are merely conducive to excessive crosswinds,
because (even if the demonstrated-crosswind statement were a limitation, and
even if there were no weather reporting at the destination) it would still
be reasonable to attempt a landing and find out if the crosswind is in fact
excessive. If not, the pilot can simply go around and try again, or divert
to a better-aligned runway. But conditions conducive to icing are usually
dangerous to probe empirically--by the time you get your answer, you may
already be in trouble. That's not always the case, but it is the case often
enough that it's reasonable to prohibit such probes (or at least much more
reasonable than it would be to prohibit you from probing the crosswind
conditions).


Just my opinion though, as I said I don't claim to know what Cessna

intended.

Yup, the FARs and AOMs are overdue for a massive rewrite. Maybe by the next
Centennial.

You're an optimist, obviously!

Matt