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Here's a VOR approach for runway 07 at Cluj (LRCL).

On the lower left side of the chart you will see the "Straight-in" OCA(H) as N/A and then a "Circling" OCA(H) of 2540 (for category C). There is only a 6 degree offset between the final approach course and the runway, and as far as I can tell below 30 degrees (or maybe 15?) the approach is considered straight-in.

So why are straight-in approaches not allowed but circling ones are?

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    $\begingroup$ I know under TERPS you can be within the straight-in cone but not able to get straight-in minima due to excessive descent rates on final (see the VOR/DME into KASE for a classic example of this) $\endgroup$ Nov 14 '16 at 23:09
  • $\begingroup$ Are you asking this question specifically about the VOR rwy 7 approach that you linked to? Or are you asking this question more generally regarding any straight in approach to runway 7 at LRCL? $\endgroup$
    – J Walters
    Nov 15 '16 at 1:59
  • $\begingroup$ @JonathanWalters just for this particular approach, why is there no straight in minima? what regulation/reason prevents a straight in $\endgroup$
    – Radu094
    Nov 15 '16 at 18:48
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It is allowed.

Runway 07 has a published GNSS straight-in instrument approach as of 10 Nov 2016.

enter image description here

Download link here, or click image for full size.

For non-GNSS equipped planes, there are no published straight-in instrument approaches for runway 07. Only the circling VOR 07.

However, in VMC the crew may request or likely be given a visual straight-in approach to 07.

As to why there aren't published minima for a straight-in VOR approach to runway 07, I can think of two plausible reasons:

  • VOR accuracy being not good in that quadrant, maybe due to terrain interference, or interference from the tall church on short final.
  • Winds almost always favor 25, so no effort was made to certify a straight-in approach using VOR for 07.

When an aircraft intends to land on a runway for which no instrument approach procedure exists, it may descend on the instrument approach to another runway and, provided the required visual references are established at the circling MDA/H, maneuver visually for landing on the desired runway. This procedure is used when landing on the instrument runway is undesirable, due for example to wind conditions or work in progress.

[...]

A circling approach is the visual phase of an instrument approach to bring an aircraft into position for landing on a runway which is not suitably located for a straight-in approach.

skybrary.aero

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    $\begingroup$ It is worth pointing out that an aircraft may request or be given a straight in approach to runway 7 via the VOR approach even while in IMC. However, in such a scenario the approach could only be continued to landing if the requisite runway environ elements were in sight at the specified circling MDA. $\endgroup$
    – J Walters
    Nov 15 '16 at 2:04
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    $\begingroup$ It's probably due to the close proximity of obstacles in the final approach segment and the accuracy of GPS versus VOR approaches in lateral guidance. GPS will keep them closer to centerline and away from those obstacles so they can descend lower. SInce the VOR has to keep them higher, they are too high to be in a position to land straight-in (similar to KASE approaches). $\endgroup$
    – Lnafziger
    Nov 18 '16 at 1:26
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What is shown on that approach isn't that a straight-in approach to the runway isn't allowed, but rather that there are no straight-in minimums published for that approach.

Why they didn't publish straight-in minima is beyond what I can tell from the chart, although the combination of obstacles near the final and reduced navaid accuracy so close to the VOR seems plausible. ("Didn't feel like it because runway 7 is rarely in use" seems less plausible: once the approach has been constructed, most of the work is done, so adding straight-in mins would be negligible extra work at that point, if the criteria were to allow for them.)

The obvious difference between the VOR approach and the GNSS approach is the allowed altitude you can descend to inside of 3 miles to the runway; a precise final approach course definition (i.e. using GNSS) would allow a narrower obstacle clearance corridor - so when you're on course there are no obstacles reaching to within XX feet vertically for YY feet laterally. The less precise guidance from the VOR probably requires a wider corridor, so if some obstacle to the side of the final intrudes on the wide corridor, its minimums have to be raised to clear the obstacle vertically. Raise them high enough, and the straight-in becomes impractical, so only circling mins are published.

Note that if you got the runway in sight & could make a safe approach and landing using normal rates of descent, you could land straight-in from a circling approach. The key point would be that below the circling MDA, obstacle clearance is no longer provided by the approach and it is the pilot's responsibility to avoid all obstacles visually.

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  • $\begingroup$ Good answer. But to reephasize an important point there are two (terps) reasons why "circling only" minimums would be published: 1. Final approach course is not aligned within 30 degrees of the runway; or 2. MDA is so high that a "normal" descent to the runway cannot be made (even though the final course is within 30 degrees of the runway alignment). Again, when circling "minimums" are published a circle is not "required" - it's that the opportunity to circle (and use another runway) is made available to the pilot with obstacle protection while at the circling MDA. $\endgroup$
    – 757toga
    Aug 3 at 16:08

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