I've been sort of casually looking for this formula for a long time to program a handheld calculator.  I know I've seen it somewhere in print before now, but I couldn't remember where.  Paul, do you have an aeronautical engineering text that you would recommend as a reference for such exquisite trivia?

Barry Knotts



Paul Lipps wrote:

It's much easier to do the upwind-downwind speed runs .......  To get density altitude, use this: dalt = baro altitude + 113.4' x (OATC + 1.88E-3 x altitude - 15C). Then get rho ratio: rr = (1 - 6.88E-6 x dalt)^4.256. Multiply the square root of rr times TAS to get IAS.