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When flying IFR into a class B airport you usually file a STAR at the end of your plan. After the last fix on the STAR you will then receive vectors from ATC to the approach for the assigned runway. At that time you would use the appropriate approach plate for information to complete the approach.

I was looking at some of the approach plates for KMEM and some of them contain multiple IAF's. For example, if you are coming in on the HOBRK 1 STAR and are assigned 36C it says that you should turn right to 53° and expect vectors after ROCAB.

HOBRK 1 plate

But when you look at the approach plate for 18C you see two extra IAF's, OWAFO and IHTEM being approached directly from the UJM and HLI VOR's respectively.

Rwy 36C plate

If one should expect to be on vectors by that point when would these other two IAF's be used?

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  • $\begingroup$ I'm pretty sure that's just for RNAV approaches - for ILS approaches, turbines follow 55° from TAMMY and are then vectored to intercept the ILS and hence straight-in, but for RNAV approaches, turbines go via OWAFO and then FREAZ, NESBT or HADAN according to selected runway. But I'm no expert! $\endgroup$
    – Fiddlesticks
    Apr 4, 2017 at 20:57
  • $\begingroup$ @user52723a Glad you pointed that out. I selected the non-RNAV STAR. I'll change it or for the HOBRK 1 rnav arrival. Very similar, though. For north ops it starts with vectors at the ROCAB fix, which is right near TAMMY. So that still doesn't explain it if they're coming off an rnav arrival. I never hear ATC mention them at all. Although, admittedly, pretty much all the AC arrive RNAV then pick up the LOC. When using parallel runways I think once they are on the LOC they can reduce required separation $\endgroup$
    – TomMcW
    Apr 4, 2017 at 22:09
  • $\begingroup$ Note that the "expect" clearance is only for situations where there is no radio communication for the crew and they need to know what you are going to do after completing the STAR. In "real world" ops, they may indeed clear you to one of the other IAF's, or maybe you aren't even flying a STAR because you are repositioning from a nearby airport or are in an aircraft which doesn't fly that high. All are situations where the feeders may be used for efficient use of the airspace. $\endgroup$
    – Lnafziger
    Apr 5, 2017 at 15:34

1 Answer 1

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Those are part of the Basic T of the Terminal Arrival Area (TAA).

The basic design of the RNAV procedure underlying the TAA is normally the “T” design (also called the “Basic T”). The “T” design incorporates two IAFs plus a dual purpose IF/IAF that functions as both an intermediate fix and an initial approach fix. The T configuration continues from the IF/IAF to the final approach fix (FAF) and then to the missed approach point (MAP). The two base leg IAFs are typically aligned in a straight-line perpendicular to the intermediate course connecting at the IF/IAF...

– AIM 5-4-8

enter image description here

They're used in vectoring. Depending on where the aircraft is coming from, it'll be directed to the dual purpose IF/IAF or one of the flanking IAF's. According to the AIM they're not used when traffic levels are high. They can be used with or without a STAR, either way they reduce the workload.

TAAs are primarily used on RNAV approaches but may be used on an ILS approach when RNAV is the sole means for navigation to the IF; however, they are not normally used in areas of heavy concentration of air traffic.

Follows is a brief description of TAA's. (Linked article is also informative.)

TAA effectively replace feeder routes, and they enable ATC to issue succinct, efficient clearances to RNAV-capable aircraft flying along an airway that passes over or near an airport or proceeding direct toward an airport from any direction. Using TAA eliminates the need for a series of vectors, which also makes them useful in areas where ATC may have poor radar coverage at the altitudes typically needed to guide airplanes onto feeder routes or the final approach course.

– bruceair.wordpress.com

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  • $\begingroup$ Do they use it in lieu of a STAR? $\endgroup$
    – TomMcW
    Apr 4, 2017 at 23:18
  • $\begingroup$ I agree with your answer, but not your comment. They aren't used instead of a STAR, and normally if you are given one of the feeders it will be after flying the STAR and entering the terminal environment.... $\endgroup$
    – Lnafziger
    Apr 5, 2017 at 15:32
  • $\begingroup$ @Lnafziger I've certainly never heard them use it. Once they leave the STAR it's vectors until they join the LOC. Then they'll give them a speed restriction until the faf and pass them to tower. I'll have to listen during the day when they're not busy some time. Maybe they do things differently $\endgroup$
    – TomMcW
    Apr 5, 2017 at 16:33
  • $\begingroup$ @TomMcW Well, a particular airport may not use them on a regular basis, but they are available for use when needed. It's quite common to use them at some other airports, depending upon the design of the arrivals and where the aircraft are arriving from. Generally, with local radar they do provide radar vectors to the final approach course because it is more efficient, but that doesn't mean it's the only way to do things. $\endgroup$
    – Lnafziger
    Apr 5, 2017 at 16:43
  • $\begingroup$ @Lnafziger That makes sense. Memphis has the good fortune of being in a flat area with no other class B or even class C airports nearby. They have more STAR's than any airport I know of because you can approach from any direction. $\endgroup$
    – TomMcW
    Apr 5, 2017 at 18:03

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