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OCA/H adjustments
28.10.2004
Submission:
The question I have is concerning "adjustments" (see paragraph 6.4.6 c) to the OCA/H and whether or not they to should or should not also be subtracted in the determination of the missed approach surface formula.
The missed approach surface formula (Chapter 21 (ILS) Paragraph 21.5.3.3.2. says (OCA/Hps - HL) + do * TanZ - MOC. This is rather straight forward but what happens in the case of a Remote Altimeter Setting (RAS) adjustment?
In the non-precision case
Should one be compensating for the RAS adjustment in the missed approach as well? To be able to check for obstacle penetrations one would have to:
Subtract the HL, do * TanZ, plus the MOC, PLUS the RAS adjustment
However aren't we penalizing ourselves twice, once by raising the OCA/H and then again by subtracting the RAS adjustment in the missed approach?
In the precision case
By increasing the OCA/H for RAS the aircraft is further on the GP so that when we minus the HL we are indeed starting our missed approach surface at the right height. So it seems the formula is correct in the precision case but the non-precision case is still in doubt.
B. Frenz - The MITRE Corporation - USA
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