I guess I've been labouring under the false belief that the only way you can pick up icing while in the air that will inhibit the safe operation of an aircraft was when you have the combination of temps being near or below freezing AND flying in visible moisture.
As far as on the ground any frost that has accumulated on a parked aircraft must be removed prior to flight ( I believe there was a C210 silver eagle turbine that crashed because it took of with a coating of frost recently) but I was unaware that once the frost has been removed it can re-accumulate while in flight without being in visible moisture.
can someone clarify for me?