Posted for "Mark Ravinski" <mjrav@comcast.net>:

 MessageHi Matt,
 Odd thing that I notice is the extreme fluctuations in airspeed while in
cruise:  5 - 8 KIAS in smooth air with no changes to power.  Auto pilot on
(with altitude hold), and Fuel flows, MP, RPM, EGT... don't budge, but
 KIAS moves up and down 5 to 8 knots...
 
 I suspect thermals.  Soes it still hapen at night?
 
 Mark Ravinski
 N360KB