It begs an interesting question, though...

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?


IN theory yes, the altitude would be different from the indicated altitude.
However, you'd only be 100 feet away from the place where the altimiter setting
was derived, so the amount of error would be slight.

Jose

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