Originally Posted by
Jetalc
I disagree with the first part, Tony. The FAF on a precision approach is at the published glideslope intercept altitude. It will never be higher, but it may be lower, if, for example, ATC has you holding at the OM at an altitude lower than the GS Int altitude and they clear you for the approach out of the hold...
Of course a precision approach has a FAF - otherwise how would you be able to comply with the reg that addresses visibility dropping below what is required for the approach (i.e., outside the FAF, at or beyond the FAF)?
The second half of your post raises the very important point that we must know when we are established on the Final Approach segment. The first half demonstrates that the answer is NOT when we cross a particular point.
I just pulled up the ILS to Rwy 18R at MEM as a "random" example. (If this link doesn't work, go to Fltplan.com and navigate to MEM, and the ILS 18R
http://204.108.4.16/d-tpp/0611/00253I18R.PDF )
The glideslope intercept altitude is 3000'. The FAF crossing altitude on glideslope is 1876'. Consider 3 scenarios. In each scenario, ATC clears the pilot for the ILS. When is he established on the Final Approach Segment? In scenario 1 he is vectored at 4000'. In Scenario 2, he is vectored at 3000'. In Scenario 3, he is vectored at 2000'.
In scenario 1, he maintains 4000' until intercepting the glideslope, and then begins down. On Final? No. Not until he passes the glideslope intercept altitude at 3000'.
In scenario 2, he maintains 3000' until intercepting the glideslope, and then begins down. On Final? Yes. And, it's at the same point over the ground as in scenario 1.
In scenario 3, he maintains 2000'. About 3.3 miles prior to intercepting the glideslope, he passes the same point on the ground where the airplanes in Scenarios 1 and 2 began their final appraoch segments. Is he then on the final approach segment? No. It is not until he intercepts the glideslope at HIS altitude that he is on the Final Approach Segment.
In fact, there could be an infinite number of points at which the Final Approach could be commenced on a precision approach - - but not a single Final Approach Fix. Not a Maltese Cross, not a lightning bolt, and not an arrow.
BROKE CFI - - Where in AIM Chapter 1?
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