taildragger173
Well-Known Member
Ok, so I remember learning this a few years ago but I'm drawing a blank now. Why is that some approaches have a final approach fix and others do not? What is the criteria for not having a final approach fix?
Final Approach Fix...or not
- Thread starter taildragger173
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meritflyer
Well-Known Member
Not necessarily. LOC approachs usually have a FAF. Typically when there is no FAF, it seems to occur when the NAVAID is off the field and there is a course reversal. In this case, the FAS begins after the course reversal intersects the FAC inbound.
taildragger173
Well-Known Member
Does DME play a role in this?
MidlifeFlyer
Well-Known Member
I'm going with 206 on this. Although many approaches based on an on-airport navaid do have final approach fixes based on another navaid or DME, these are the ones that are most likely to have no FAF. Merit, there may be some with an off-airport navaid, but your discription fits what is probably the majority on-airport NDB and VOR approaches - you start down after the PT precisely because there is no FAF to start the descent at.
At this point they are probably most common at remote areas where there might not even be another VOR in enough range to identify an intersection as an FAF.
At this point they are probably most common at remote areas where there might not even be another VOR in enough range to identify an intersection as an FAF.
meritflyer
Well-Known Member
Exactly what I was referring to.
MidlifeFlyer
Well-Known Member
If there is DME associated with the primary navaid for the approach there is (almost) always be an FAF. I think the only time there isn't one is when there would be no way to identify one.
For an example, here's the current EGT NDB 35:
http://naco.faa.gov/d-tpp/0706/06626N35.PDF
MidlifeFlyer
Well-Known Member
Right, but that happens with on-airport navaids, not off-airport navaids. Compare that EGT one I just posted with this one at 2K3 - the NDB is pretty close - only 2.7 miles from the runway but it's still used as an FAF.
http://naco.faa.gov/d-tpp/0706/06590N17.PDF
I guess there could be one that is so close to the airport but off it that it has to be treated the same or violated TERPS criteria for descent profiles.