The approval codes for light aircraft requires that the ASI is within 5 knots full range, but in my experience many struggle to meet that - especially near the stall.. .. .Many STOL aeroplanes will stall at 45°+ nose-up, and most microlights or smaller light aircraft around 30° nose-up (attitude, not AoA), even without power - so altered AoA are big players in what you actually see on the gauge. With such a high AoA, whatever's happening to the wing, usually the pitot is so far from pointing directly into the airflow, that it drops to something silly (I've seen as low as 8kn) IAS at the stall, when the aircraft is probably doing around 30-50.. .. .As for the KISS principle, I think that probably died somwhere early on page 2. Commendable approach though.. .. .G. . . . <small>[ 09 March 2002, 20:44: Message edited by: Genghis the Engineer ]</small>