"noah" wrote in message om...

Basically - is it bad for the aircraft (C172) to float around at
around 85kts with the power somewhere below the green arc (say
1800rpm) and the Carb-Heat on? Ok, there is a second benefit - my club
charges based on tach time, and I have to be honest about that -
although I really do wish for the tours to be slower.

Most of the dirt is pretty close to the ground. Unless you're flying through
a duststorm or volcanic erruption, at altitude there shouldn't be much harm
in leaving the heat on.