Originally Posted by
TonyC
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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Sorry, Tony - maybe it's me, but it seems like you're talking in circles, and saying, in a different way, what I already stated. In your first two examples, the published GS int altitude is the same, regardless of where the GS is intercepted. It is the PUBLISHED altitude that counts. You repeated what I had already said. In both cases (int at 4000 and int at 3000), the spot over the ground that is considered the FAF is the same. That is a point that can be found to have the same lat/long, GPS fix, whatever.
According to the Pilot/Controller Glossary:
"FINAL APPROACH FIX- The fix from which the final approach (IFR) to an airport is executed and which identifies the beginning of the final approach segment. It is designated on Government charts by the Maltese Cross symbol for nonprecision approaches and
the lightning bolt symbol for precision approaches; or when ATC directs a lower-than-published glideslope/path intercept altitude, it is the resultant actual point of the glideslope/path intercept. I believe that's what I already said.
Not sure what you mean by "On final." You could be aligned with the runway centerline, heading toward the runway, and not even be on the Final Approach Segment (since the intermediate segment ends at the FAF, by definition). Do you mean "at the FAF?"
You state: "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." Well, I agree with you, but that's NOT what we're talking about. We're talking about the definition of a FAF, not where you believe you're "turnin' onto final." Big difference.
A fix, according to the FAA, is simply a generic term "used to define a predetermined geographical position used for route definition. A fix may be a ground-based NAVAID, a waypoint or defined by reference to one or more radio NAVAIDs." Perhaps you have issue with the use of the FAA's word "Fix" in "Final Approach Fix," since the geographical position isn't always the same?
The FAA uses the word "Final Approach Fix" in many instances, and not unintentionally:
"(2) Glide Slope Critical Area. Vehicles and aircraft are not authorized in the area when an arriving aircraft is between the ILS final approach fix and the airport unless the aircraft has reported the airport in sight and is circling or side stepping to land on a runway other than the ILS runway. "
"The primary ILS approaches for Los Angeles are attached for reference. Both contain an abundance of “slow-down-while-going-down,” but the 25 ILS is arguably worse, because the speed brakes can be deployed on the 24 approach, and some attempt can be made to play catch up before the precision final approach fix (PFAF). "
"The final approach fix is generally situated anywhere from 3˝ to 5 miles from the runway threshold. The pilot will normally prepare the aircraft so that it is configured and ready to fly a stabilized descent by the time the aircraft intercepts the glideslope."
There isn't enough room here to post the thousands of times the FAA uses the word "ILS Final Approach Fix."
If it is the word "fix" you have a problem with, maybe you can coerce the FAA into changing it. However, stating (erroneously) that there is no FAF on a precision approach is misleading at best. Arrogant and ignorant at worst, and I'm not sure which category you fall into, since I don't know you.