"Peter Duniho" wrote in message
...
"Robert Lyons" wrote in message
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- Why would this problem affect just FL180 and FL200? Why not FL160,
220,
and every other altitude?

It affects all flight above FL180. There is no "FL160" in the US, and I'm
not sure why you got the impression that flights at FL220 are unaffected.

It'd have to be a hell of a depression to affect FL220 though. The table in
the relevant regulation (14CFR91.121) doesn't allow for such sucky weather.

-- David Brooks