Circling Approach

Captain

Captain

Final Approach
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Mar 12, 2012
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First Officer
There are three reasons why a Circling Only Approach are published per the TERPs. (Ya know...Like a "VOR-A").

Anyone care to guess the three? An approach reference for each equals bonus points.



Super extra Bonus:
I can get all three in 1 State with 2 airports. Can ya top that?
 
obstacle

improper runway alignment

VOR reception below a certain altitude



not enough time to come up with a reference for each
 
1. Approach does not meet straight-in alignment criteria (final approach course aligned within 30 degrees of the extended runway centerline)
Ex. VOR/DME-C RIL

2. Excessive descent gradient (max 400 ft/nm)
Ex. VOR/DME or GPS-C ASE

Not sure what the third one is. I can't find anything in TERPs (8260.3B) about a third case.
 
Oops, I lied. I can't get them all in 2 airports anymore. It appears they decommissioned one of my example approaches.

BTW, first two reasons are correct. Excessive descent rate and excessive course alignment (greater than 30 degrees to runway). Only one left and it's the rare one that I only have 1 example of.
 
1) Generally anytime the FAS is not aligned to the runway center line base on specifications for the particular approach category. For RNAV approaches a LNAV can be aligned within 30 degrees of the runway centerline and a LPV can be aligned within 15 degrees of the runway centerline. See order 8260-3b and or 8260-54a with specifics based on the particular approach type. For ground based Navigation aids, there is also a criteria for the maximum offset from the runway centerline that is permitted and category C or above have different limits in terms of permitted angle and offset.

2) Descent from MDA too steep, see paragraph 252 in order 8260-3b (The
MAXIMUM descent gradient is 400 ft/NM which approximates a descent angle of 3.77°.)
 
Okay, I'll give a hint. KFPR, NDB-A.

That's the approach that demonstrates a circle for the third reason. Any ideas why it's a circling approach?
 
i don't know but how the hell do you get from 28R/10L to the rest of the airport???
 
i'm guessing its because the approach course intercepts the runway extended centerline too far out. there is an NDB to 28L which seems to be right on the ragged edge of 30 degree alignment
 
It is a variation of the alignment issue as I noted in my response under reason number 1. I don't believe this is a unique number 3, but if you can come up with a different explanation, I am willing to learn.
 
Captain said:
Okay, I'll give a hint. KFPR, NDB-A.

That's the approach that demonstrates a circle for the third reason. Any ideas why it's a circling approach?
Click to expand...

The final approach course is more than 30 degrees off the runway 32 extended centerline so it can't be a straight in to runway 32. Also, it crosses the runway 28L extended centerline more than 5200 feet from the 28L threshold so it also fails to meet the straight in alignment criteria in TERPs.
 
tonycondon said:
i don't know but how the hell do you get from 28R/10L to the rest of the airport???
Click to expand...

You don't. They built that runway recently to alleviate some of the training traffic from the main runway. It's just for touch and go's.
 
The third criteria is they draw a box at the end of the runway. I can't remember the exact dimensions but its like 700' wide at the threshold and 2,000' wide 1,400' from the threshold. The approach course has to go through that box, within 30 deg of runway alignment and a normal descent rate to qualify for straight in mins to be published.

In the case of the NDB-A in FPR the approach course is within 30 degrees, the descent rate is normal but the course misses the box. Notice on the NDB 28L they crank the approach course up 15 degrees and thus manage to hit the box and be within 30 degrees of the runway (ragged edge as Tony pointed out).

So, there's the 3 criteria for straight in mins to be published.

1. Course within 30 degrees of runway (15 for LPV)
2. Normal descent rate
3. Approach Course must go through the box at the end of the runway. (Sorry I can't remember the exact dimensions.)
 
Captain said:
The third criteria is they draw a box at the end of the runway. I can't remember the exact dimensions but its like 700' wide at the threshold and 2,000' wide 1,400' from the threshold. The approach course has to go through that box, within 30 deg of runway alignment and a normal descent rate to qualify for straight in mins to be published.

In the case of the NDB-A in FPR the approach course is within 30 degrees, the descent rate is normal but the course misses the box. Notice on the NDB 28L they crank the approach course up 15 degrees and thus manage to hit the box and be within 30 degrees of the runway (ragged edge as Tony pointed out).

So, there's the 3 criteria for straight in mins to be published.

1. Course within 30 degrees of runway (15 for LPV)
2. Normal descent rate
3. Approach Course must go through the box at the end of the runway. (Sorry I can't remember the exact dimensions.)
Click to expand...

Under the NDB section on straight in alignment is the following paragraph. This is all the same topic and is what I wrote about in my previous post. Such paragraphs exist for each approach type and consists of several constraints on alignment. IOW, it is not a flat 30 degrees. If you consider this several rules as opposed to a complex alignment rule as described, then the approach category C and above would constitute a fourth for the 15 degree and so on. IOW, there are two criteria, not 3.

(1) Straight-In. The angle of convergence of the FAC and the extended runway centerline shall not exceed 30°. The FAC should be aligned to intersect the extended runway centerline 3,000 feet outward from the runway threshold. When an operational advantage can be achieved, this point of intersection may be established at any point between the runway threshold and a point 5,200 feet outward from the runway threshold. Also, where an operational advantage can be achieved, a FAC which does not intersect the runway centerline or intersects it at a distance greater than 5,200 feet from the threshold may be establishad, provided that such course lies within 500 feet, laterally, of the extended runway centerline at a point 3,000 feet outward from the runway threshold. Straight-in category C, D, and E minimums an not authorized when the final approach course intersects the extended runway centerline at a an angle greater than 15° and a distance less than 3,000 feet.
Click to expand...

figure 55 alignment options for FAC, On airport NDB.jpg
 
John Collins said:
Under the NDB section on straight in alignment is the following paragraph. This is all the same topic and is what I wrote about in my previous post. Such paragraphs exist for each approach type and consists of several constraints on alignment. IOW, it is not a flat 30 degrees. If you consider this several rules as opposed to a complex alignment rule as described, then the approach category C and above would constitute a fourth for the 15 degree and so on. IOW, there are two criteria, not 3.



View attachment 26377
Click to expand...


Interesting. Where's that quoted bit from?
 
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