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3 Answers

Why there’s only IAF without FAF on some NPA charts?

Asked by: 916 views Instrument Rating

Hi. I have another question. Why there're only an IAF without FAF on some NPA charts, as in the VOR RWY 2 chart of KIDA? Does that fact that there's only an IAF and no FAF have any implications for shooting the approach, compared to shooting NPA charts with both IAF and FAF?

Chart link:

3 Answers

  1. Russ Roslewski on Jan 18, 2017

    There is no FAF designated because this is a no-FAF approach.

    I know that sounds like a bit of circular reasoning, sorry.

    Not all procedures have FAFs. On your basic, simple, old-style VOR approach like this one, you make your procedure turn, then once you’re lined back up on the final approach course, you are essentially at a “FAF”. But this point will be different each time you fly the approach depending on wind and airspeed and such. And it will be different depending on the speed of the airplane you’re flying and how far out you take the procedure turn.

    So no FAF can be designated, because there is no “Fix” for you to fly over. You just start down to the MDA once you are turned around and established on final.

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  2. Lemontree on Jan 18, 2017

    Thank you for your detailed explation Russ. Reading your explanation, I got curious whether the existence of FAF on a NPA chart might be related to the existence of obstacles in your approach course. As you explained above, when there\’s no FAF designated, I can start my descent whenever once I\’ve finished my PT. But if there\’s an obstable that can penetrate my approach course when I descend, obviously the chart designers would not allow me to start my approach whenever possible after PT, and would rather make pilots extend their PT inbound to a certain fix and designate it as a FAF.

    So would it be wrong to believe that there was no necessity to designate a FAF on this NAP chart because pilots would not confront any obstacles anyway as long as they finish their PT and start their descent within 10 miles of the IDA VOR? Does it make sense?

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  3. Best Answer

    Russ Roslewski on Jan 19, 2017

    Well, not really. Having a FAF or not having one is not directly determined by the obstacle environment. Obstacles just determine the minimum altitude. Other considerations (such as available NAVAIDS) determine whether or not to publish a FAF.

    In this procedure, for example, to have a FAF, you need a way to identify it. Either a crossing radial or a DME fix would work. Perhaps no other VOR is available, and if you make it a DME fix, then you limit the approach to those aircraft with DME. In this case, there was presumably nothing gained by doing that, so it was left as a no-FAF procedure.

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