Christopher Brian Colohan wrote:

Think of it this way -- your car has windshield wipers. In light or
moderate rain, they let you drive in the weather without any problem.
But in an absolute downpour they may not be able to keep up, and so
you are better off pulling over and waiting for the rain to pass...

When I was recently sitting on an airliner waiting to take off, we were
told that we couldn't take off because at the time there were both
freezing rain and ice pellets. We were told that they could take off if
either went away, but not as long as both continued. They claimed it
was an FAA requirement.
--
Gene Seibel
Tales of Flight - http://pad39a.com/gene/tales.html
Because I fly, I envy no one.