Turning at the IAF....

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pstan

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Stan
Trying to liven up the group (is that a word?)

We've all seen it..."procedure not authorized for arrivals via V123 southwestbound", for example on some rnav(gps) approaches. I think this is because terps does not normally allow a turn greater than 120 degrees when a feeder route leads to an IAF. Guru's please correct me.

However, is there anything that restricts a pilot from requesting, or an atc from clearing, a flight to an iaf where the turn at the iaf requires more than 120 degrees of turn?

If yes, then why? Especially cat A that can fly so slow to allow this turn easily I'd think, and remain withing 4 miles of the centreline even with wind considerations.

If no, why does terps have this restriction, but still allow atc to permit, or pilots to perform, the maneouvre?

Stan
 
You are correct about the 120 degree restriction in the TERPS.

Nothing restricts a pilot from asking for it (nothing restricts a pilot from ASKING for anything, of course). :)

I do not THINK anything restricts ATC from approving it, but someone else is likely more of an expert on ATC than me. If they have you in radar contact at or above the MVA I wouldn't think it'd be a problem.

As to WHY TERPS has this restriction for all aircraft is probably that it hasn't been a big enough issue, and thereby caused enough public interest, for AFS to modify it. In addition, the approach plates are already complicated enough, with new notes proliferating like crazy. No way anybody wants to see "Procedure NA for Cat A arrivals via V123 southbound, Cat B arrivals via V123 and V456 southbound, Cat C via V123 and V456 southbound and V789 southwestbound, etc."

To keep it simple, you need to account for the worst case.
 
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RussR said:
I do not THINK anything restricts ATC from approving it, but someone else is likely more of an expert on ATC than me.
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My guess would be no, after some of the turn-on's I asked for and got while flying part 135 freight. (when I was younger and dumber, and I got a 10% bonus every day if all of my 7 flights every night were on time)
 
Speed said:
My guess would be no, after some of the turn-on's I asked for and got while flying part 135 freight. (when I was younger and dumber, and I got a 10% bonus every day if all of my 7 flights every night were on time)
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I never got a bonus.:dunno: Lucky freight dog.
 
Arnold said:
I never got a bonus.:dunno: Lucky freight dog.
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I suppose it might be better worded as a 10% penalty if you weren't on time for every flight... even by a minute. :rolleyes2:
 
RussR said:
I do not THINK anything restricts ATC from approving it,
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According to the FAA Flight Procedures Branch, controllers are not permitted to clear you for a turn of more than 120 degrees at the IAF of an approach which has no course reversal.

As to WHY TERPS has this restriction for all aircraft is probably that it hasn't been a big enough issue, and thereby caused enough public interest, for AFS to modify it.
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It's an issue of protected airspace and the descent gradient to the next point.

To keep it simple, you need to account for the worst case.
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Exactly -- including speed and wind.
 
Ron Levy said:
According to the FAA Flight Procedures Branch, controllers are not permitted to clear you for a turn of more than 120 degrees at the IAF of an approach which has no course reversal.
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So I guess the answer is, when about 20 miles approaching the IAF on V123 southwestbound, ask for turns so that you (a) are no longer on V123 and (b) will require less than a 120° turn when reaching the IAF.

Simple :D
 
midlifeflyer said:
So I guess the answer is, when about 20 miles approaching the IAF on V123 southwestbound, ask for turns so that you (a) are no longer on V123 and (b) will require less than a 120° turn when reaching the IAF.

Simple :D
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That's what I've done in the past as well. :)
 
midlifeflyer said:
So I guess the answer is, when about 20 miles approaching the IAF on V123 southwestbound, ask for turns so that you (a) are no longer on V123 and (b) will require less than a 120° turn when reaching the IAF.

Simple :D
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I've never seen an approach which didn't have a better option than that. Typically you see something like that on one IAF which really makes no sense for arrivals from that direction anyway, since there's a better choice available from that direction. Either that, or the approach is stamped RADAR REQUIRED because the only entry is vectors to final.
 
pstan said:
Trying to liven up the group (is that a word?)
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Yes.

We've all seen it..."procedure not authorized for arrivals via V123 southwestbound", for example on some rnav(gps) approaches. I think this is because terps does not normally allow a turn greater than 120 degrees when a feeder route leads to an IAF. Guru's please correct me.
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It's because approach designers have acquired a taste for superfluous notes on IAPs.

However, is there anything that restricts a pilot from requesting, or an atc from clearing, a flight to an iaf where the turn at the iaf requires more than 120 degrees of turn?
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There's nothing that restricts a pilot's request, JO 7110.65 restricts ATC from clearing a flight for the approach with a turn greater than 90° at the IAF.
 
Ron Levy said:
According to the FAA Flight Procedures Branch, controllers are not permitted to clear you for a turn of more than 120 degrees at the IAF of an approach which has no course reversal.
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Where can the FAA Flight Procedures Branch be found?
 
midlifeflyer said:
So I guess the answer is, when about 20 miles approaching the IAF on V123 southwestbound, ask for turns so that you (a) are no longer on V123 and (b) will require less than a 120° turn when reaching the IAF.

Simple :D
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You'd probably want to ask for a new clearance limit too.
 
Rotor&Wing said:
That's probably a part of the FAA ( Faux Aviation Administration) :D
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Perhaps, although I can't imagine why anyone would direct an ATC question to them, or to the Flight Procedure Standards Branch of the real FAA.
 
Ron Levy said:
I've never seen an approach which didn't have a better option than that.
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They probably are few and far between. After all, if you need more than a 120 to get there, it means you've already passed it and there was probably an earlier turn.

An example I can think of off the top of my head is the BCT RNAV 5 http://tiles.skyvector.com/sky/files/tpp/1104/pdf/00560R5.PDF My guess is that if coming northbound on V159, you would have been turn in toward FEYFO (or vectored to final) long before reaching ATONE.
 
roncachamp said:
Where can the FAA Flight Procedures Branch be found?
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Oklahoma City, although they often coordinate with other branches of AFS-400 which are located at HQ in DC. And I apologize for omitting the word "Standards" from their full official title.
 
Ron Levy said:
Oklahoma City, although they often coordinate with other branches of AFS-400 which are located at HQ in DC. And I apologize for omitting the word "Standards" from their full official title.
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Which branch of AFS-400 is responsible for ATC procedures?
 
roncachamp said:
Perhaps, although I can't imagine why anyone would direct an ATC question to them, or to the Flight Procedure Standards Branch of the real FAA.
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AFS-410 is the AFS place to go with procedural issues. The do interface with ATO. Not always too well, but they try.
 
Ron Levy said:
I've never seen an approach which didn't have a better option than that. Typically you see something like that on one IAF which really makes no sense for arrivals from that direction anyway, since there's a better choice available from that direction. Either that, or the approach is stamped RADAR REQUIRED because the only entry is vectors to final.
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If center or approach has radar capability they certainly can vector you to any early segment of an IAP.
 
aterpster said:
AFS-410 is the AFS place to go with procedural issues. The do interface with ATO. Not always too well, but they try.
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410, 420, and 470 work together on these matters. I usually start with Flight Procedures Standards, but often they send me to one of the other two to get a specific answer. And as Wally noted, they do interface with ATO on these issues, so what they're telling us should be what ATO is telling the controllers.
 
aterpster said:
If center or approach has radar capability they certainly can vector you to any early segment of an IAP.
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I think you know that's currently under discussion. At this point, the only way controllers can vector you to join a segment of a SIAP is vectors to the final approach course per Section 5-9 of the ATC Handbook. The only other option currently available besides direct-IF for Advanced RNAV aircraft on RNAV(GPS) and GPS approaches is to send the aircraft to an IAF. The FAA is looking at other options, such as vectors to join an initial or intermediate segment not aligned with the final approach course, but that's not yet been approved/codified.
 
Ron Levy said:
I think you know that's currently under discussion. At this point, the only way controllers can vector you to join a segment of a SIAP is vectors to the final approach course per Section 5-9 of the ATC Handbook. The only other option currently available besides direct-IF for Advanced RNAV aircraft on RNAV(GPS) and GPS approaches is to send the aircraft to an IAF. The FAA is looking at other options, such as vectors to join an initial or intermediate segment not aligned with the final approach course, but that's not yet been approved/codified.
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All that is being discussed is RNAV direct to the IF on ground-based IAPs. Vectors to any portion of a feeder route or intitial approach segment has always been approved under the general provisions of 7110.65, 5-6-1. It's no different than a vector to an airway. Vectors to intercept DME arc initial approach segments is also a common practice.
 
aterpster said:
All that is being discussed is RNAV direct to the IF on ground-based IAPs. Vectors to any portion of a feeder route or intitial approach segment has always been approved under the general provisions of 7110.65, 5-6-1. It's no different than a vector to an airway. Vectors to intercept DME arc initial approach segments is also a common practice.
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They may be a common practice, but the FAA has said they're not authorized. And there's nothing in 7110.65 authorizing controllers to issue an approach clearance in conjunction with a vector to join a segment of a SIAP other than the "vectors to final" guidance in 5-9. I went through that with AFS-400 a while back while researching an article I was writing.
 
Ron Levy said:
They may be a common practice, but the FAA has said they're not authorized. And there's nothing in 7110.65 authorizing controllers to issue an approach clearance in conjunction with a vector to join a segment of a SIAP other than the "vectors to final" guidance in 5-9. I went through that with AFS-400 a while back while researching an article I was writing.
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You need to rely less on AFS on air traffic procedures and more on ATO.
 
This is where ATO will take you:

7110.65
4-8-1 b. For aircraft operating on unpublished routes, issue the approach clearance only after the aircraft is: (See FIG 4-8-1.)

1. Established on a segment of a published route or instrument approach procedure.
 
aterpster said:
You need to rely less on AFS on air traffic procedures and more on ATO.
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Well, they told me they'd coordinated their answer with ATO. In any event, pilots have to rely on the guidance in the pilot pubs like the AIM and IPH, and there's nothing there about joining approaches in midstream other than VTF and, for GPS approaches, direct-IF.
 
Ron Levy said:
Well, they told me they'd coordinated their answer with ATO. In any event, pilots have to rely on the guidance in the pilot pubs like the AIM and IPH, and there's nothing there about joining approaches in midstream other than VTF and, for GPS approaches, direct-IF.
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The language I cite from 4-8-1 makes it quite clear that you can be vectored onto a feeder route or an initial approach segment. The IAF requirement in the first part of 4-8-1 is for non-radar operations and was added because of the November, 1994 non-radar legal ruling about IAFs.

For my entire carrier, ATC used radar to take me off airways, and back onto them, off SIDs and back onto them, and off IAPs and back onto them (well inside the IAF but prior to the FAF). It was even done inside the IF in the days before the IF was charted.

In fact, many times I changed routes and was vectored from one Victor airway to a different Victor airway.

There is no reason why this would have to be discussed or explained in any pilot procedures documents.
 
From Chapter 8 of the IFH:

The plan view provides a graphical overhead view of the procedure, and depicts the routes that guide the pilot from the en route segments to the initial approach fix (IAF). [Figure 8-10] During the initial approach, the aircraft has departed the en route phase of flight and is maneuvering to enter an intermediate or final segment of the instrument approach. An initial approach can be made along prescribed routes within the terminal area, which may be along an arc, radial, course, heading, radar vector, or a combination thereof.

That's lifted directly from TERPs, Paragrah 230. No such reference to radar is made for feeder routes because a feeder route is a de facto airway.
 
Ron Levy said:
I think you know that's currently under discussion. At this point, the only way controllers can vector you to join a segment of a SIAP is vectors to the final approach course per Section 5-9 of the ATC Handbook. The only other option currently available besides direct-IF for Advanced RNAV aircraft on RNAV(GPS) and GPS approaches is to send the aircraft to an IAF. The FAA is looking at other options, such as vectors to join an initial or intermediate segment not aligned with the final approach course, but that's not yet been approved/codified.
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Nonsense. A vector to join an initial approach segment, such as the MTW R-260 on the VOR/DME RWY 18 approach at KFLD, is completely consistent with JO 7110.65 Air Traffic Control.
 
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Ron Levy said:
They may be a common practice, but the FAA has said they're not authorized. And there's nothing in 7110.65 authorizing controllers to issue an approach clearance in conjunction with a vector to join a segment of a SIAP other than the "vectors to final" guidance in 5-9. I went through that with AFS-400 a while back while researching an article I was writing.
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If they told you that they were incorrect, but I think it more likely that you misunderstood what they told you.
 
Ron Levy said:
Well, they told me they'd coordinated their answer with ATO. In any event, pilots have to rely on the guidance in the pilot pubs like the AIM and IPH, and there's nothing there about joining approaches in midstream other than VTF and, for GPS approaches, direct-IF.
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Which means there's nothing in the pilot pubs like the AIM and IPH that suggests ATC cannot vector aircraft to join an initial approach segment not aligned with the final approach course.
 
roncachamp said:
Which means there's nothing in the pilot pubs like the AIM and IPH that suggests ATC cannot vector aircraft to join an initial approach segment not aligned with the final approach course.
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...except for this part in the AIM 5-4-7:
e. Except when being radar vectored to the final approach course, when cleared for a specifically prescribed IAP; i.e., “cleared ILS runway one niner approach” or when “cleared approach” i.e., execution of any procedure prescribed for the airport, pilots shall execute the entire procedure commencing at an IAF or an associated feeder route as described on the IAP chart unless an appropriate new or revised ATC clearance is received, or the IFR flight plan is canceled.
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Yes, they can vector you onto a feeder route, but not to join past the IAF other than vectors to final. The only exception is noted elsewhere (direct-IF for GPS approaches).
 
Ron Levy said:
...except for this part in the AIM 5-4-7:
e. Except when being radar vectored to the final approach course, when cleared for a specifically prescribed IAP; i.e., “cleared ILS runway one niner approach” or when “cleared approach” i.e., execution of any procedure prescribed for the airport, pilots shall execute the entire procedure commencing at an IAF or an associated feeder route as described on the IAP chart unless an appropriate new or revised ATC clearance is received, or the IFR flight plan is canceled.
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'Nuff said.

Yes, they can vector you onto a feeder route, but not to join past the IAF other than vectors to final. The only exception is noted elsewhere (direct-IF for GPS approaches).
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Please cite the paragraph of JO 7110.65 Air Traffic Control that you believe supports your assertion.
 
roncachamp said:
'Nuff said.
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Suggest re-reading that paragraph more closely. That "appropriate" part you highlighted refers to breaking off the approach after you've been cleared for and started it, which you cannot do without a new/revised clearance or cancellation of IFR. It does not refer in any way to joining the approach.
 
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