Originally Posted by FREDAcheck
I'm not about to correct Genghis, but my understanding from what he said is that what you really want is CAS not IAS. That is (roughly) IAS corrected for things like positional errors. Not a big difference, but for example flying slowly with high angle of attack, the pitot tube isn't pointing exactly into the air stream, and (I think) result in IAS being a few knots lower than CAS.
CAS (rather than TAS) is the indicator of how the plane will perform, so it's what you want to know on landing.