On the ground, freezing rain does to an airplane just what
it does to your car. The entire airplane is clobbered.
Doors won't open or close properly. Flaps, ailerons and
spoilers may be frozen in position.

Before take-off, airlines spray boiling hot water on the
airplane (180° or so) to remove the snow and ice, then they
switch to a heated mixture of water and anti-freeze to keep
any ice from accumulating on the airplane during the time it
takes to taxi and take-off. As rain/snow fall on the plane
and melt, the antifreeze solution become diluted and the
water will begin to freeze in hinges and such.

The FAA parts 121 and 135 do not allow take-off in certain
extreme icing conditions, but pilots have the authority to
NOT GO even when the regulation might allow.

In-flight, the aircraft anti-and de-icing systems will
handle typical icing encounters, but severe icing is defined
as ice that build TOO FAST for even the equipment to handle.

see
http://ecfr.gpoaccess.gov/cgi/t/text...1.21&idno= 14
and
http://ecfr.gpoaccess.gov/cgi/t/text...1.14&idno=1 4



"Christopher Brian Colohan" wrote in
message .. .
| "Peter R." writes:
| Christopher Brian Colohan wrote:
|
| first, it means that the planes
| will fly through the freezing levels quickly (and up
higher where it
| is too cold for ice accumulation), so they don't pick
up much ice.
|
| Thanks, Chris. Regarding the above, that may be true
for departing
| aircraft, but what about aircraft on approach to a busy
airport? It is
| certainly probable that these aircraft may be vectored
around at lower
| altitudes for many minutes at slower speeds. I would
imagine that if this
| occurs in heavy freezing rain this could be a real
problem, no?
|
| (speaking from a complete lack of experience...) I also
imagine that
| this could be a problem, and I would guess that the
solution is "don't
| do that". If a plane is picking up ice, the solution is
to leave the
| icing conditions -- either climb or descend. I'm sure ATC
would allow
| a plane to do this if a request was made.
|
| Chris