"M" wrote in message
ps.com...

BTW, FAR 91.144 restricts flight operations when barometric pressure
exceeds 31 inch mercury. Any idea why? (note this restriction applies
to VFR traffic a well).


The Kollsman Window is only required to have a range of 28.00 to 31.00
inches Hg. So if barometric pressure is outside that range, you cannot
accurately set most altimeters.

John Severyn
@KLVK