ILS:. .. .Yup, good point on configuration.. .. .But, uh density altitude does not change the stall speed indicated??. .. .True airspeed yes. . .Say yer Cessna 172 usually stalls at 65 knots indicated at max weight, straigt and level fligth flaps up. At 10,000 feet density altitude, it still stalls at 65 knots INDICATED.. .. .As for compresebiltity, well perhaps on a fast jet, but the 172 hardly runs into such.. .. .(I know, we did not specify A/C type or other specifics, the list was just a general, get yer mind thinking kind of excerize). .. .I am however not the judge in what goes on the list or not, if others agree on density altitude, then parhaps I was wrong...? <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" />