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Where does the final approach segment begin on an ILS approach? It may not be as simple as it sounds to answer. The reason I ask is because I've found some support for at least two answers.

One is that final begins when passing the glide slope intercept point a the last no lower than altitude for the approach. This is the point denoted by the lightning bolt arrow on government charts.

glide slope intercept

Another answer I've heard is that it begins when glide slope has be intercepted within the limitations of the glide slope and on an approach segment. For the example plate above, this would mean that if the glide slope were intercepted between SILKY and JAKOR the pilot would be considered to be past the final approach fix for all intents and purposes and might even configure the airplane for landing at that point rather than passing JAKOR at the published glide slope intercept.

I think there are valid arguments for both, but I'd apprecate more insight and references on the topic.

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up vote 8 down vote accepted

No arguments needed, it's very specifically defined. According to the FAA's Pilot/Controller Glossary under SEGMENTS OF AN INSTRUMENT APPROACH PROCEDURE:

c. Final Approach− The segment between the final approach fix or point and the runway, airport, or missed approach point. (See ICAO term FINAL APPROACH SEGMENT.)

So it starts at the FAF, which is defined in the same document as:

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, designating the PFAF, for precision approaches; or when ATC directs a lower-than-published glideslope/path or vertical path intercept altitude, it is the resultant actual point of the glideslope/path or vertical path intercept.

In your example, that means the final approach segment starts at JAKOR. I may be wrong here, but your original thought might have been that the final approach starts when you're established on the glideslope, which could be outside JAKOR. That makes sense in a general way, but it isn't how the term is defined.

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It's pretty easy to answer as best I can determine: The Final Approach Segment begins at the Final Approach Fix. On FAA/NACO charts this is shown on the profile view with the Maltese cross:

LGA VOR 04 profile view

The "lightning bolt arrow" (or as the FAA calls it, the "zigzag line") designates the precision approach glideslope intercept altitude This is usually coincident with the final approach fix (and the specified altitude serves as the minimum crossing altitude for the final approach fix if the glideslope is inopertive or not in use), but it does not appear on non-precision approach charts, as shown above.

The final approach fix may also be marked in the plan view with the annotation (FAF).

You may have intercepted the glideslope before the FAF as you describe in your second scenario (particularly on a continuous-descent profile) or you may have done a dive-and-drive to that point because the glideslope is out of service before starting your final descent as in your first scenario, but for purposes of the approach segments the FAF marks the beginning of the final approach segment.

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This actually came up in one of the Jeppesen "Chart Clinic" articles, which is a pretty good read: ww1.jeppesen.com/download/aopa/jul99aopa.pdf – voretaq7 Feb 25 at 21:59
That Jepp document is such a great read, thanks. – Ryan Burnette Feb 26 at 12:22

The lightning bolt is the final approach fix for precision approaches and the Maltese cross is the final approach fix for non-precision approaches.

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Why the downvote, folks? This information is correct. – Jonathan Walters Feb 26 at 1:10
@JonathanWalters it's too simple lol – Jon Andis Feb 26 at 2:43
Those two symbols DEPICT the FAF, but only on particular charts. Reread the question, it isn't asking how the FAF is depicted. – Ralph J Feb 26 at 3:31
@JonAndis Read the accepted answer for clarification. – Ryan Burnette Feb 26 at 12:25
There's also something to be said for brevity. – Ryan Burnette Feb 26 at 12:26

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