Flying an RNAV from an IF

Discussion in 'Cleared for the Approach' started by George Mohr, Sep 16, 2019.

  1. George Mohr

    George Mohr Line Up and Wait

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  2. benyflyguy

    benyflyguy Pattern Altitude

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    I don’t see why not. In fact looking at it it looks like they’re doing a favor has to go out to the initial approach fix was at least 10 to 13 miles out of the way. I think the only way you would not except it if you needed more time to get down from being high and fast. I think you have to be at least 5 miles away from that fix to take that clearance.
     
  3. Ravioli

    Ravioli Final Approach

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    Sounds like you got to cut a corner. You should accept it, request it, and thank them for it. IF arriving HIVDO at 2500' and on speed are non-issues. SMA looks to be 3300'
     
  4. George Mohr

    George Mohr Line Up and Wait

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  5. mryan75

    mryan75 Cleared for Takeoff

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    If you're getting vectored I don't see why not. I got vectored to the FAF yesterday, skipping the IAF.
     
  6. flyingron

    flyingron Touchdown! Greaser!

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    You DON'T need to be vectored. Cleared to an IF is different than vectors to final. Both are legitimate subject to other limitations.
     
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  7. chemgeek

    chemgeek Cleared for Takeoff

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    Syracuse will clear you direct to the IF on the RNAV approaches to expedite arrivals if you direction of flight allows. Kind of like getting a shortcut vector without vectors, and efficient for both pilot and ATC.

    This is another reason to NEVER NEVER NEVER use "vector-to-final" in your GPS box else you will be doing the dance of the seven veils to get the box reprogrammed to go direct to the IF. Even if ATC initially tells you to expect vectors. The last time I selected VTF on the SYR GPS 10, I got a last minute change to direct MOYIK (IF) instead. Doh! I should know better.
     
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  8. benyflyguy

    benyflyguy Pattern Altitude

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    Guilty!!!
     
  9. IK04

    IK04 Cleared for Takeoff

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    From my brief experience flying out of Watertown/Wheeler Sack, I can say the SYR Approach guys were very accommodating and always kept our approaches short unless we asked for the full approach. They seemed bored at night and were happy to work us.

    I could get four approaches done in the time it took to do three. That more than made up for the transit time from Fort Drum...
     
  10. James331

    James331 Touchdown! Greaser!

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    Yes
     
  11. mryan75

    mryan75 Cleared for Takeoff

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    What box do you have, and how do you set up the approach instead? I have a 650 and use VTF all the time (getting vectored on 127.42 into KRME).
     
  12. PaulS

    PaulS Final Approach

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    This, atc tried to trick me a couple weeks ago telling me to expect VTF, I sensed it was a trick and didn't fall for it. Sure enough he cleared me to the IAF, but he did say "when able" to give me time to program it in, it was already in there. Then within about 8 miles of the IAF, he started vectoring me, so I hit VTF, don't forget that. Ifr flying can be fun.
     
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  13. aterpster

    aterpster Pattern Altitude

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    In my view, VTF should never be used, not for those who have a good command of how to sequence the IAP legs.
     
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  14. PaulS

    PaulS Final Approach

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    Nice view, but if you understand how to use VTF and how to recover if you are tricked it's NBD. Picking the correct leg can sometimes be more work.


    Edit: It really depends on what avionics you are using though, how you've been trained and what you are comfortable with. It's not a one size fits all deal.
     
    Last edited: Sep 16, 2019
  15. midlifeflyer

    midlifeflyer Touchdown! Greaser!

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    I don't disagree that if one is used to doing something it becomes easy. But can you give an example of where loading an IAF initially makes it more work if there is a change in the expected instruction? I fly with all the current Garmin navigator ps and have passing familiarity with Avidyne, so any example should work.

    I became a "no-VTF" guy (on initial load) long before the AIM recommendation to avoid using it. It was immediately after watching someone "tricked" into having to reload an approach, pretty much from step one, on a G1000. Seen that scenario since with other pilots. A few I was flying where I thought, "here's another example" although I wasn't "tricked" because I loaded with a IAF. Even one involving a GTN with the update including the fixes on the extended FAC (sent me to an IAF on the end of the T instead of to the expected IF due to traffic).

    OTOH, I am not religious about avoiding VTF later in the process. Once clear, for example, that the next step is going to be interception inside any outside waypoints, i don't see a problem with "activate VTF" as opposed to "activate leg" although there is a legit argument for an "activate leg" preference.
     
  16. PaulS

    PaulS Final Approach

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    Mark, I'm flying the Perspective + system now, which is Cirrus version of G1000 nxi (I'm sure you know this but for others who may not). There are so many ways to do this we are getting tripped up in it in this discussion. I always load the full approach to the IAF that makes the most sense for where I am, I almost never load VTF unless I absolutely know I'm being vectored, like when flying from a missed procedure and the controller tells me to expect vectors.

    Around here 95% of the approaches are VTF by ATC, but that 5%, which can be a surprise, are the ones that can trip you up, so I wait to hit the VTF button until I am sure. That said, getting the approach reloaded is just a few button pushes, no big deal if you're proficient at it.

    Activating VTF after the full approach is loaded is pretty easy in the Perspective system. Hit PROC, a couple clicks on the knob, and a button push and you are done. Where as activating a leg is generally more pushes and more thought, but you've already pointed out the other reason VTF can be better, that's when you are vectored beyond the last fix on the final approach course.

    Just don't forget to push VTF or to activate a leg, otherwise things get interesting when close in and you realize you are not going to intercept the final. Hand flying it is.

    Finally, I'm pretty new at this, so I'm parroting what I've been taught, with a little but growing mix of what I've learned so far thrown in.
     
  17. Jabe Luttrell

    Jabe Luttrell Filing Flight Plan

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    I don't program VTF in my 530s unless I am VFR and just want the glidepath. I request from ATC the initial approach fix I want. If I don't then they will vector me inside the IAFs and IFs And I'll have to be on HDG mode with my autopilot then at the last second I'll have to reprogram the GPS to some other fix and try to get it to switch to NAV mode so I can couple to the approach. It's usually very messy. ATC is still in the mode of vectoring to an ILS approach course and glideslope that require no reprogramming to intercept at any usable distance. The RNAV approaches need setup at a predefined waypoint in order to give a nice stable approach. Although ATC vectored you to a IF as a "favor" or shortcut, at least in my GPS and Foreflight accepting it would require VTF and I would ask for an IAF instead. Makes my life easier.
     
  18. Adam Weiss

    Adam Weiss Pre-takeoff checklist

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    I always program in the the fix I’m expecting for the approach. Then if I get vectors, it’s really only a few button pushes to switch to vectors on the 650. No big deal.
     
  19. midlifeflyer

    midlifeflyer Touchdown! Greaser!

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    I agree with your, um, perspective ;)

    Yes. Depending on the setup, there may be an advantage of one over the other in certain circumstances, but at that final push, VTF and activate leg are mostly just two ways to get to the same result.

    One of the stated overall advantages of activate leg, which is why many are teaching it, is simply getting used to using the Menu key, which provides expanded options. There really isn't much of a difference in the number of button pushes so, the theory goes, might as well use the expanded option one consistently, so when you want to use it, it doesn't take "more thought."

    It is, of course, a matter of individual preference. And that preference may reflect other preferences. For example, when I fly an approach on a G1000, I personally like to keep the flight plan open on the MFD, so the pushing is pretty much the same either way.
     
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  20. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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    On the TBM (3-screen G1000 with 15" MFD) I'll usually have the flight plan up (FPL on top, map lower left, VNAV lower right), and if it's going to be a visual approach I'll load VTF to the RNAV to the appropriate runway and skip the mins. If they specifically say it'll be vectors to final I'll activate VTF, but I haven't run into the situation where they tell you to expect VTF and then change their mind yet. I'll have to play with that a little in VMC.
     
  21. midlifeflyer

    midlifeflyer Touchdown! Greaser!

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    I saw it the first time well years before the AIM recommendation to avoid VTF when I was still in Colorado. It was a Class C and the change was for spacing. Basically a longer downwind and a FAC join at a waypoint further out. I've seen it a few times since, but not that many. In both they were the type which would be available on the latest Garmin software updates (not the GNS unit's).

    I try to toss one in if I'm doing a recurrent training session with someone who loads VTF to see what they do. My First Commandment for instructors is to avoid imposing changes to techniques that work (it happened to me and it took years to undo). So if they handle it, no big deal. If they get confused we talk about how it happened and alternatives on the ground.
     
  22. coma24

    coma24 Line Up and Wait

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    And now, a reading from the 7110.65...

    7110.65Y 4-8-1 H.(2) (d)
    Ok, the 'behold' part, not so much. The jist of it, though, is that ATC can absolutely can clear you to the IF for an RNAV approach provided they tell you that is the plan (assuming other IAFs exist. If there are no IAFS, just an IF, then it's implied). Intercept angle has to be 90 degs or less.

    Additionally, they can clear you to a fix between the IF and FAF provided the intercept angle is 30 degs or less (similar to a VTF) provided the resulting descent gradient works (they'll need to keep you at or above MVA until said fix).

    Edit: for reference, here's the FAA order on ATC: https://www.faa.gov/documentLibrary/media/Order/7110.65Y_8-15-19_for_PRINT_(Signature).pdf. Page 220'ish (4-8-4 in the footer).
     
    Last edited: Oct 8, 2019
  23. GMascelli

    GMascelli En-Route

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    BTDT, not happening again. It's way too easy to load the approach and have it available then to reload when single pilot IMC. A simple click to fly a specific leg is an easy chug and plug on the 530.

    I'm now flyng the Garmin 480 in my Commander, it took me a bit to get used to it, but some of the features are actually easier then the 530.

     
    Last edited: Oct 8, 2019
  24. N1120A

    N1120A Line Up and Wait

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    IAFs are for lost comms. If you get an ATC clearance somewhere, that is your new clearance in case of lost comms. I get clearances to intermediate fixes all the time.
     
  25. RussR

    RussR Cleared for Takeoff

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    Along these lines, how does the 430/530 and others handle vectors-to-final when there is a turn at the FAF? How does ATC handle these? There are not too many of those in my part of the country, so I haven't flown one recently. But for an example, look at the Logan, UT LGU RNAV (GPS) RWY 17:

    https://skyvector.com/files/tpp/1910/pdf/00663R17.PDF

    If it were to plot the final approach course straight out from the FAF, that doesn't seem quite right given the approach. But neither would a turn at the FAF from vectors-to-final.

    (I have no idea if people ever get vectors-to-final on this specific approach, it was just the first example I found of a turn at the FAF.)
     
  26. dtuuri

    dtuuri En-Route

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    Attached Files:

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  27. RussR

    RussR Cleared for Takeoff

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    Great article, and is exactly what I was asking about. After I posted, I ran the Logan, UT approach in the GTN750 simulator and it did the same thing as in John's article above - plotting the intermediate segment as the one you were being vectored to intercept.

    I will say that John's alternate option #1 is exactly how we would do vectors-to-final with the GNC-300XL, since it didn't have a "Vectors to final" option. We'd go into OBS mode and set the OBS to the final course.
     
  28. dtuuri

    dtuuri En-Route

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    Note the definition from the P&CG:

    FINAL APPROACH COURSE−
    A bearing/radial/track of an instrument approach leading to a runway or an extended runway centerline all without regard to distance.​

    I would infer the latter applies to vectors for a visual approach and the former an instrument approach track.
     
  29. aterpster

    aterpster Pattern Altitude

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    Or, for non-radar areas. Lots of those in the intermountain west.
     
  30. N1120A

    N1120A Line Up and Wait

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    Will ADS-B adoption change that?
     
  31. aterpster

    aterpster Pattern Altitude

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    That's the plan. I don't know enough about the center's display of ADS-B whether it will be of sufficient fidelity to provide vector capability to an IF.

    I recall that oceanic ADS-B will use 10 miles between targets as opposed to 5 miles for center radar and 3 miles for approach control radar. For oceanic 10 miles instead of 10 minutes is a very significant improvement.
     
  32. flyingron

    flyingron Touchdown! Greaser!

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    You still have MVA (or at least MIA) altitudes to worry about even with ADS-B. Flying airway to IAF may me more preferable than having to intercept the approach at a higher "minimum" altitude, no?
     
  33. aterpster

    aterpster Pattern Altitude

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    Correct.
     
  34. N1120A

    N1120A Line Up and Wait

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    Oh sure, but that depends on how the approach is designed.
     
  35. aterpster

    aterpster Pattern Altitude

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    And how the approach is designed often depends upon the terrain in mountainous areas.