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6 Answers

GPS holding with 4nm leg – ENTRY

Asked by: 13017 views General Aviation

So, most of the GPS holds are 4nm outbound leg and when entering with parallel or teardrop entry, should I fly 1min and turn inbound and intercept track towards holding fix?

 

If yes, teardrop entry will not be 30 degrees but shallower.

 

Connor.

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6 Answers



  1. Russ Roslewski on Oct 29, 2016

    GPS holding leg lengths are altitude-dependent (go look up some higher altitude airports to see), and the value specified is the maximum leg length allowable. GPS receivers will generally plan to fly both the entry and the actual holding pattern out to this distance before turning around.

    But it’s a maximum. You are free to shorten it if you wish. Timing should never be necessary on a GPS hold, but I suppose you could do it if you want. Just look at your distance to the fix.

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  2. Mark Kolber on Oct 30, 2016

    I agree with Russ. Unless ATC specifically instructs a leg length, it is a maximum. But if you are going to be a purist about it, a hold with a NM leg length is a hold in which one would toss out the concept of timing, even for the entry.

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  3. connor on Oct 31, 2016

    Thank you Russ,

    Since FAR/AIM does not specify timing on entries, could you post some credible links or reference ?

    Connor

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  4. Russ Roslewski on Oct 31, 2016

    Sure it does. Have you read AIM 5-3-8? It includes the timing for standard holding leg lengths.

    In addition:

    AIM 5-4-9a(5) and Page 4-49 of the Instrument Procedures Handbook contain almost identical text:

    “A holding pattern-in-lieu-of procedure turn may be
    specified for course reversal in some procedures. In
    such cases, the holding pattern is established over an
    intermediate fix or a FAF. The holding pattern distance or
    time specified in the profile view must be observed. For a
    hold-in-lieu-of PT, the holding pattern direction must be
    flown as depicted and the specified leg length/timing must
    not be exceeded. ”

    Note the “must not be exceeded” at the end. Shortening them is okay.

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  5. MasterFlight on Nov 01, 2016

    This is one of those topics that instrument instructors have been disagreeing about for decades. The language in the AIM is a bit ambiguous. In the very same quote above it also says the published time or distance “must be observed.” That said, I can’t imagine you would be cited for turning early, so I don’t really want to engage the interpretation-of-the-guidance argument.

    The question really should be, what is the safest procedure? If you are flying a GPS that provides steering through the entire hold entry, and you have coupled an autopilot to that GPS, the lowest workload procedure would be to let the automation fly out to the published distance. If you are hand flying and turn early, do you know in advance how the GPS will sequence the remainder of the entry? Or are you setting yourself up to need to manually intervene with the automation right before the FAF? If you don’t know the answers to those questions, then it is best to fly the procedure as charted.

    What’s the rush?

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  6. Russ Roslewski on Nov 01, 2016

    > The question really should be, what is the safest procedure? If you are flying a GPS that provides steering through the entire hold entry, and you have coupled an autopilot to that GPS, the lowest workload procedure would be to let the automation fly out to the published distance.

    Undoubtedly the easiest and lowest workload.

    > If you are hand flying and turn early, do you know in advance how the GPS will sequence the remainder of the entry? Or are you setting yourself up to need to manually intervene with the automation right before the FAF? If you don’t know the answers to those questions, then it is best to fly the procedure as charted.

    While I agree that if you don’t know how your GPS works it would be best to fly the full thing, I would argue that if you don’t know how your GPS works regarding a simple holding entry, you need some additional training. This is one of those things that every one of my instrument students (that have an IFR GPS) gets practice in and is exposed to.

    For the ubiquitous Garmin 430W, for example, there is nothing to do. You shortcut it, it figures it out and sequences appropriately.

    > What’s the rush?

    While I agree with the general sentiment of “take your time and don’t hurry”, these GPS maximum holding leg lengths are sometimes way, way longer than they need to be for many aircraft. They are maximum leg lengths based on maximum holding speeds at the published altitude and accounting for TAS increases with altitude.

    See the Fort Bridger, WY, KFBR RNAV (GPS) RWY 22:
    https://skyvector.com/files/tpp/1611/pdf/00148R22.PDF

    That Hold-in-lieu you’d use coming from the FBR VOR/DME has a published 7 nm leg length. If this was a VOR-based hold you’d go outbound for a minute, covering 1.5 miles if you’re flying at a not atypical 90 knots, and everybody would think that was normal and safe. So you have added a completely unnecessary 5.5nm x 2 = 11nm onto your flight. Even taking your time to avoid being rushed doesn’t take THAT much extra time.

    When faced with this situation, I’d rather a client tell me that he’s not going to go out the full distance and be able to explain why, than to have them go out to the distance depicted by rote, when that distance is simply a MAXIMUM length, not a minimum or mandatory length.

    Yes, the paragraphs in the AIM and IPH could be better written.

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