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13 Answers

VOR approach

Asked by: 4259 views FAA Regulations, Instrument Rating

Looking at the VOR RWY 14 into SRQ.  If I got the ATC instruction of 'Fly direct SRQ, cleared VOR RWY 14 approach'.  I then turned direct to SRQ and am now on a heading of 145.  I am making the assumption that I've spoke to ATC and they will not clear me straight-in. 

 

What would be the correct way to get established outbound on the R-298 radial?  In this instance I would probably turn LEFT once I got over the VOR and then fly back to it and establish outbound on a HDG of 298.  Of course, I am assuming that my altitude is 2800ft.  

13 Answers



  1. Bryan on Jan 01, 2022

    I don’t think ATC would give you “direct to SRQ” if that would put you on a 145 heading given this approach. They would prefer you on the ground ASAP which usually means giving you straight in…especially where the nav aid is on the field and a 145 heading would be a really good intercept course for the 118 final approach heading. So unless you were less than 5 miles from the field already, they would likely just vector you onto the final approach course.

    But, taking your hypothetical, you’re approaching from the northwest and the protected side of the approach is to the south (you can tell because that’s where the barb goes for the procedure turn) and within 10 NM of the field. I know this is Florida and you don’t have much by way of mountains but I did all my flight (including instrument) training in Utah where approaches are set up like this because there are mountains all over the place. I do not think there is a single “correct” way to do the turn–but I do think that you have some checkride busting sorts of concerns and some practical concerns.

    To me, the checkride busters would be turning before you cross SRQ and descending from 2,800 before you’re established outbound. If you do those two things, all of your maneuvering and descending is taking place on the protected (south) side of the approach course. Those are the safety-critical issues.

    The practical consideration in this approach has to do with the cone of confusion.The 207 degree left turn you describe could work and be safe as long as you stay south of the final approach course as you intercept it. The problem with it is that you will be trying to intercept the 298 radial directly over the VOR–in the cone of confusion. That would be unwise without GPS because you do not want to risk straying north of the final approach course (there could be mountains and it’s dark outside so you can’t see them).

    Your other option is a 153 degree right turn to intercept the outbound course. The right turn will take you a mile or so away from the VOR which will make detecting (and therefore intercepting) the 298 radial much easier even if you only have VOR on board (no GPS).

    Remember, as long as you stay within 10NM of the field, you can make the procedure turn wherever you want. So eating up a mile or so with a right-hand turn to intercept the outbound still keeps you on the protected side of the approach course and won’t be a big deal for your procedure turn.

    One final thought…imagine doing this approach at night with no visual references whatsoever and there were mountains nearby. Under those conditions and given the option, I’ll take a 153 degree turn over a 207 degree turn every time.

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  2. Gary Y on Jan 01, 2022

    Thanks for the reply.

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  3. John D Collins on Jan 02, 2022

    After crossing SRQ, I would just turn right in a 180 degree turn to an intercept the outbound 298 degree radial On intercepting the 298 radial outbound, track it outbound, begin the descent to 1700 and do the PT, staying within the 10 NM limit of SRQ. After completing the PT and intercepting the 298 radial inbound, descend to 520. If you have DME or GPS and can determine JELSU, step down to 440.

    I think the right turn to intercept the 298 radial is easier than a left turn so close to the VOR.

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  4. Mark Kolber on Jan 04, 2022

    On this approach scenario I first remember that the AIM tells us we have options so long as we make the turn inbound on the barbed side.

    For my turn outbound, I don’t think there is any reasonable choice other than turning right. First, it is on the maneuvering side (although that’s not required for an outbound turn), so there’s more protected room. But more important to me, ta turn to the right involves a shorter turn than any option for a turn to the left.

    Where I differ with John a bit is that given my approach to SRQ VOR, I’d make my outbound turn to parallel the outbound. I’d treat is the PT as a racetrack (one of the AIM options). and make a familiar and simple direct entry. I figure, why make a 180 degree turn when 155 will to the job nicely, especially when it’s the equivalent of a basic directed entry to holding pattern, a maneuver we practice regularly.

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  5. John D Collins on Jan 04, 2022

    Mark, I agree that one can just enter a holding pattern, but it is not clear if you can begin the descent from 2800 to 1700 as noted in the OP assumption until established on the 298 radial.

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  6. Mark Kolber on Jan 04, 2022

    I guess we disagree.

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  7. Mark Kolber on Jan 05, 2022

    John, I had a longer comment but it disappeared, it came down to the question, how long do you have to be established on the 298 radial before being able to descend to the outbound altitude. 2 minutes? 1 minute? 10 seconds? The 1 second it took to cross the VOR, during which you crossed that radial?
    To me neither the AIM description of the maneuver nor the regulations say anything about being established on the radial outbound. To the contrary, all the AIM talks about is maneuvering on the maneuvering side, with the only reference to the outbound radial being if one is approaching from the maneuvering side and, in this example, making a left turn outbound (akin to a parallel hold entry).

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  8. Russ Roslewski on Jan 05, 2022

    From an obstacle clearance standpoint, at SRQ it really doesn’t matter when you start descending if you are doing a holding pattern-style entry.

    There is no maximum entry altitude charted, which means that the largest procedure turn template was used for evaluation. This allows for a primary area with 1000 feet of obstacle clearance that is an oval roughly 25 nm long, 14 nm wide at the PT fix and 16 nm wide at the point 10 nm away from the PT fix on the inbound course.

    This is huge.

    The holding pattern protected airspace at that altitude would be 14.4 nm long by 8.8 nm wide and provides the same 1000 feet of obstacle clearance. While the exact shapes differ, the holding pattern airspace would fit completely within the procedure turn airspace – the PT area is much, much larger.

    So, entering a holding pattern and descending to 1700 anywhere in the holding pattern isn’t going to hit anything.

    Since this is an on-airport VOR approach with no FAF, I would make sure to go outbound far enough, regardless of if I’m doing a PT or a holding entry, that I can make the descent from 1700 to the runway at a reasonable rate. Trying to intercept the final course about 6 nm out would be a good target I think, give you a little time to get set up and start a normal 3 degree descent. Of course, in an airplane like a 172, this would mean an outbound leg of about 4 minutes if no-wind conditions. If you follow the “1 minute outbound” by rote in a 172, you will be turning onto the inbound course (whether PT or holding pattern) only 1.5 nm from the runway, and still have to lose 1700 feet!

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  9. John D Collins on Jan 05, 2022

    Mark,

    I don’t know what happened to your longer discussion, but I called another friend and he agrees with you that you can descend, so I learned something.

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  10. Gary Y on Jan 05, 2022

    Further question based on these answers; Is that protected side on just the approach end i.e. NW of the VOR or both NW and SE (within 10NM of the VOR)?

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  11. Best Answer


    Russ Roslewski on Jan 05, 2022

    In the SRQ example, it extends 7 nm southeast from the VOR (to allow for maneuvering as you turn around to get on the outbound course) and 18 nm northwest from the VOR (to allow for all the vagaries of airspeed, wind, timing, pilot technique, etc).

    And then there is an additional 2 nm buffer area, known as a “secondary area” where you are further protected, surrounding the area I described above.

    Reference is FAAO 8260.3E, Figure 2-4-8 and Table 2-4-4, although it’s a little hard to understand without some background knowledge.

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  12. Gary Y on Jan 05, 2022

    Great answers. Plenty of learning. Diagram was very useful. Thank you everyone who contributed.

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  13. Mark Kolber on Jan 08, 2022

    John, when we stop learning, it’s all over.

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