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Old 18th Apr 2022, 07:55
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Originally Posted by Clop_Clop View Post

The issue was about MDAs for this approach and why they have three ones available. Of course need to assume the appch is flown per chart vor cdfa and with dme and also comply with the at or aboves for any fixes there as well... My point was about the 650' (w D2.8) or 780' (w D3.8) minimas earlier.
That is just the way Jepp publishes step down fixes inside the FAF, the charts in the Indian AIP has them as step down fixes. These step down fixes have nothing to do with reported visibility, or missed approach climb gradient. It is for terrain clearance.

"Stepdown Fixes

Occasionally a fix is located on the final approach segment between the FAF and the MAP. This fix is not a final approach fix, but it is called a stepdown fix and is used on nonprecision approaches. When this fix can be identified during the approach, you normally get lower minimums after passing the stepdown fix.

The stepdown fix is used primarily for two reasons. First, there are many cases in which there is a high obstacle in the final approach segment that would cause very high landing minimums. In this case, the FAA will designate a stepdown which is placed beyond the controlling obstruction in the final approach segment. After you have identified and passed the fix, you can descend to the MDA for the airport.

The second reason is when the final approach segment is excessively long, the TERPs criteria requires the MDA to be raised. When the final approach segment exceeds six miles, the MDA is increased at a rate of five feet for each one-tenth of a mile over six miles. When a stepdown fix is incorporated in the final approach segment, the basic obstacle clearance is applied between the stepdown fix and the MAP.

Sometimes, a constant descent rate cannot be made from the FAF down to the runway since a stepdown fix altitude might be higher than the constant descent angle from the FAF to the runway. In these cases the descent rate after the stepdown fix will not exceed 400 feet per nautical mile, or 3.77, and still have straight-in landing minimums."
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