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enter image description hereIs it possible to carry out a CDFA approach if there is no defined final approach fix mentioned on the instrument approach chart?

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  • $\begingroup$ Just to add some extra context to this question, internationally the FAF, FAP, CDFA, CDA may differ from how they are recognised by the FAA. A good few paragraphs on this are found in the wikipedia page “Final Approach” - Section “Final Approach Fix and Final Approach Point” en.wikipedia.org/wiki/… $\endgroup$ Commented Sep 14, 2023 at 15:51

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Your Question: Can a CDFA approach be carried out if there is no final approach fix?

The answer is yes, a CDFA approach can be conducted without a depicted FAF. I encourage you to read the FAA's AC 120-108A, linked below, for a full explanation of CDFA techniques (which can vary depending on the equipment in your aircraft, navaids, fixes, dme, etc. available and shown on the approach chart, etc.).


From the FAA's AC 120-108A - Subject: Continuous Descent Final Approach:

paragraph 3-1: Equipment Requirements. A CDFA does not require specific aircraft equipment; however, the aircraft must be equipped to accomplish the NPA procedure. Pilots can safely fly NPAs with a CDFA using basic piloting techniques, aircraft flight management systems (FMS), or RNAV systems. Pilots can use points defined by a DME fix, crossing radial, GPS distance from the runway, etc., on the approach plate to track their progress along both the lateral and vertical approach paths to the MAP.

And

paragraph 3-2 (pertinent excerpt) Approach Requirements. A CDFA may be flown on any NPA. There are no specific approach requirements nor any requirement for a vertical descent angle (VDA), glide path (GP), or visual descent point (VDP) to be published on an IAP in order to fly a CDFA.

[...]

Lastly, from the FAA's Pilot/Controller Glossary::

FINAL APPROACH POINT- The point, applicable only to a nonprecision approach with no depicted FAF (such as an on airport VOR), where the aircraft is established inbound on the final approach course from the procedure turn and where the final approach descent may be commenced. The FAP serves as the FAF and identifies the beginning of the final approach segment.

(emphasis is mine)

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  • $\begingroup$ To add to the discussion, the definition of the FAP varies. As far as I am aware, in Europe, The FAP is only typically used in reference to ILS approaches. There is a good description of this on wikipedia, using the case of Alicante airport, Spain en.wikipedia.org/wiki/… $\endgroup$ Commented Sep 14, 2023 at 15:58
  • $\begingroup$ @tedioustortoise Yup, I totally agree. My response was only directed to U.S. CDFA (which are very similar to the rest of the world), and linked to the approach plate the OP was asking about. That is why I referenced FAA in my response. $\endgroup$
    – user22445
    Commented Sep 14, 2023 at 16:02
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    $\begingroup$ Yep totally agree and you are right in doing so of course, just wanted to add a little extra :) $\endgroup$ Commented Sep 14, 2023 at 16:07
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CDFA is possible. The VDA is published after the fix from which it applies. In this case, that is AMBAZ. The VDA calculation has nothing to do with the MAP location or the MDA.

See the FAA’s AC 120-108A that was just released in March ‘23.

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For the KLAL VOR 27 approach, it is possible to perform a CDFA type approach. On these types of approaches with a procedure turn, the FAF is defined as alignment with the final approach course after the procedure turn.

There is a DME distance available and a descent angle on the chart. The descent angle suggests approximately 300 FT/NM descent. The TDZE is 142 and the TCH is 45 or a threshold crossing altitude of 187.

If you were at 2,000 FT MSL just finishing up the procedure turn a descent should be made at (2000 - 187) / 300 = 6.0DME is where you start the descent.

But notice, that puts you on a descent path to the MAP after the runway begins and you may need to circle if you complete the CDFA and can see the runway.

It is best to dive and drive this type of approach so you can be in a position to land when you break out of the clouds. Especially since the runway will be to your right and not directly in front of you.

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    $\begingroup$ You’re not flying a CDFA if you’re using 6 DME to begin your descent. That is not at all how you are supposed to use the information on the chart. $\endgroup$
    – Timbo
    Commented May 20, 2023 at 4:23

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