I was under the impression that AH displays IAS (indicated airspeed) mph, with the standard white needle, and the just added feature of the red-slash in TAS (ground speed) mph.
From what I have seen, the only aircraft data or references that typically use knots in either TAS or IAS, are the US Navy or maybe a few foreign navy's aircraft.
But I could be wrong.
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Vermillion
WB's: (verm--), **MOL**, Men of Leisure,