Chimbu Chuck,
How does this work??
Light aircraft don't (usually) have an ADC, or any other digitized IAS data, the Garmin 330 Mode S transponder plus GDL 90 GPS source has no IAS input of any kind, I was not aware that IAS was a required input into an ADS-B/C message??
Tootle pip??
PS: Re. Class E airspace, can ATC really give an exemption to a statutory speed limit. Last time I read the rules, ATC could only waive a speed limit in A and C??
But maybe I have missed an amendment??
Unfortunately, 250 kt. is often a very inefficient speed for many large aircraft, particularly on climb at heavy weights. Anybody for Flaps 1 to 10,000 on a 744 at max weight. Not any time this pilot is flying one, see the airplane flight manual.