Calculating best alt

Date:         07 Dec 98 23:19:29 
From: (Zirkball)
Organization: AOL
Followups:    1 2
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Is there a formula airline dispatchers use for assigning best altitudes given
distance between cities? Assuming a no wind situation, what would it be?
It appears that for flights 100 miles apart 16-18000 seems to be the norm, for
for 200NM, 22000 seems normal. Any thoughts?