Oh my gosh... the explanation again...
NormalSpeed gave a correct wording and print of the DA(H)...
Decision altitude (height)...
We will speak strictly "USA" here...
A normal ILS is flown to 200 feet DH
(above threshold elevation).
If that elevation is, say, 213 feet MSL...
That ILS would have printed minimums as - DA(H): 413' (200')...
XSFUgimpLB41X (wow, a tongue twister - or finger twister you are)
Most people call that "413 feet" in the above example a DH
It is a decision altitude, really, but I agree with you, 75% of USA pilots erroneously say DH
Suppose we now deal with a real DH
Radio altimeters are used for Cat.II approach minimums...
They measure a HEIGHT above the ground below the aircraft.
If it is, and let's assume absolutely flat terrain, the DH
will be generally 100' DH
Your decision to land will occur at RA
100' (height). You will not look your normal altimeter.
That normal altimeter indicates altitude, it (would) read something like 313 ft at time of DH
But your decision is based on RA
), not on a DA on Cat.II -
Suggest you research what I have discussed many times about QNH and QFE in the past.
A QNH altimeter setting (like in USA) gives altitudes.
A QFE altimeter setting (sometimes used outside USA) gives heights above TDZE.
A QNE altimeter setting (cruise levels) is 29.92 - 1013.2 - 760 gives levels.