"Peter R." wrote in message
...
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?


Bleed air from the engines is used to warm things up enough to unstick the
ice on the heavy stuff. Lighter air craft use things like inflatable boots
on the leading edge of the wings and props to mechanically knock the ice
off. Or, Fluid systems are used that spread de-icing fluid onthe wings and
props during flight. Electric heat has been used for propellors.

See also
http://en.wikipedia.org/wiki/Ice_protection_system

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