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When we examine the "VOR A" Jeppesen chart on LTAF airport page 23-4, we see that there are only circle-to-land minimums in the minimums section. When I researched the reasons for using circle-to-land instead of straight-in-land, I found the following reasons:

  • The final approach course alignment with the runway centerline exceeds 30 degrees.

  • The descent gradient is greater than 400 ft/NM from the FAF to the threshold crossing height (TCH). When this maximum gradient is exceeded, the circling only approach procedure may be designed to meet the gradient criteria limits. This does not preclude a straight-in landing if a normal descent and landing can be made in accordance with the applicable CFRs.

  • A runway is not clearly defined on the airfield.

However, when we examine the LTAF airport 23-4 page Jeppesen "VOR A" chart, we see that none of these conditions exist. The approach path is exactly the same as the final approach course (228°) and the descent gradient is less than 400 ft/NM.

So why weren't straight-in-land minimums specified in this chart, and we were asked to apply circle-to-land only with circle-to-land minimums for the airport?

LTAF VOR A

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    $\begingroup$ The reasons you found mention "the CFRs" which refers to the United States Code of Federal Regulations, promulgated by the United States Federal Aviation Administration. The FAA has no jurisdiction over LTAF airport and so the explanations you quote are unlikely to apply, at least directly. $\endgroup$
    – randomhead
    Commented Oct 20, 2022 at 21:07
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    $\begingroup$ I notice that the NAVAID providing final approach course guidance is on the far side of the airport from the final approach course, which is not (in my experience) how things are usually set up. Perhaps that is relevant? $\endgroup$
    – randomhead
    Commented Oct 20, 2022 at 21:08
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    $\begingroup$ I expect the answer is due to the 591' obstacle within 1-2 miles of the threshold $\endgroup$
    – Ben
    Commented Oct 20, 2022 at 22:09
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    $\begingroup$ ...it isn't steep enough to qualify for circle-to-land. I hope you can understand the difference between them, @Ralph J. $\endgroup$
    – pilot162
    Commented Oct 20, 2022 at 22:26
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    $\begingroup$ If you read my comment above, you can understand that fmp (rate of descent) and ft/NM (descent gradient) values are not the same things. What we are evaluating here is whether the descent gradient is more than 400ft/NM. When we calculate the descent gradient using the fpm values in the table, we find that it is 342ft/NM (I won't explain how I found it here in detail). So our descent is less than 400ft/NM. That's why I asked my question. @StephenS $\endgroup$
    – pilot162
    Commented Oct 22, 2022 at 8:36

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I believe it is because there is a 591ft obstacle between MAPt and threshold. I have quoted the MOC from ICAO DOC 8168 Volume II for each of the different segments of the approach.

Initial segment (Part I - Section 4, Chapter 3.3.4):

The obstacle clearance in the initial approach primary area shall be a minimum of 300 m (984 ft). In the secondary area, 300 m (984 ft) of obstacle clearance shall be provided at the inner edge, reducing linearly to zero at the outer edge.

Intermediate segment (Part I - Section 4, Chapter 4.3.2.1):

A minimum of 150 m (492 ft) of obstacle clearance shall be provided in the primary area of the intermediate approach segment. In the secondary area, 150 m (492 ft) of obstacle clearance shall be provided at the inner edge, reducing to zero at the outer edge.

Final segment, for non-precision straight-in approaches without vertical guidance (Part I - Section 4, Chapter 5.4.3.1):

The OCA/H for a straight-in, non-precision approach where the angle between the track and the extended runway centre line does not exceed 5 degrees shall provide the following minimum obstacle clearance (MOC) over the obstacles in the final approach area: a) 75 m (246 ft) with FAF; and b) 90 m (295 ft) without FAF.

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