If an IAP is based on object clearance (in some cases, as low as 100'
clearance, right?), but does not account for temperature variations and
does not actually measure geometric altitude above the ground, is it not
possible that one would find oneself at an altitude that from a
barometric standpoint is legal and correct, but from a geometric altitude
is within the bounds of that tower that would have been 100' lower if it
also changed altitude with the temperature?


Just a thought...

And a good thought it is. Try this:
http://www.aircraftbuyer.com/learn/train06.htm

John Bell
www.cockpitgps.com