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3 Answers

Clarifications on unusual approach plate Notes and layouts.

Asked by: 739 views Commercial Pilot, FAA Regulations, General Aviation, Instrument Rating

If you look up the approach plate for KOCF ILSDME 36, the note section states that 'simultaneous reception of VOR and LOC is required.

First, if you are going to shoot the ILS approach into KOCF, do we really need to receive VOR unless you are doing the DME arc? I understand its use for the Localizer approach, because you really need to identify step-downs using DME distance from VOR!

Secondly, some of the approaches such as VOR9 into KLAL does not have the IAF but IF. What I heard from one of my colleague is that radar vectoring substitutes the initial segment of the approach procedure and I am still not finding credible information where it exactly mentions. If above 'suggestion' from my colleague is true, what are the conditions that IAF is omitted from the approach procedure?

Third, going through the TERPs publication, I found out intriguing facts on 'Descent gradient' on non-precision approaches. From my viewpoint, TERPs seemed recommending min & max descend gradient for approach procedures with different type of procedure turns and IAF. As a pilot, would you recommend analyzing what D.G to apply and put that into calculation every time you go out for instrument flying?


3 Answers

  1. John D Collins on Jan 14, 2017

    First, OCF 5.9 DME is the only way to identify FIBUS. There is a feeder route from OCF to FIBUS as an IAF with a PT required for the inbound leg. The other three IAF locations are the two DME arcs and the the IAF at SADEY. It is obvious the DME arcs require DME and the SADEY IAF needs to be able to identify the IF TALZA, which is only available via OCF DME. In addition, the only way to identify the FAF and the MAP on the LOC/DME version requires OCF DME. So no matter how you fly this procedure, you need DME.

    Second, your colleague is correct. There are many approaches that begin at an IF and require Radar. This is often because of high volume of traffic and the inefficiency in using aircraft navigation to transition from the enroute environment to the approach environment. In the TERPS, section 11-2 Radar Approaches states:

    11-2-2. Feeder Routes and Initial Approach Segments.
    a. Feeder and initial segments do not need to be established when navigation guidance and obstacle clearance are provided by ATC radar vectors during the transition from the en route to the terminal phase of flight.

    Third, the pilot is expected to evaluate all segments of the approach including evaluating their speed and rate of descent to comply with the published procedure. It is a normal part of the instrument approach briefing. Example I have to loose 500 feet in 4 NM, what kind of speed and descent rate will accomplish that. So at 120 Kts, I have 2 minutes to descend and loose 500 feet, 500 feet per minute will support up to a 1000 foot descent in the 4 NM, so it is a very usable descent rate for the segment.

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  2. connor on Jan 15, 2017

    Sir, if I am being vectored for the approach, I do not need to receive VOR correct?

    Also, when ATC is providing obstacle clearance, are they taking both MVA and Diverse Vector Area into account?


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  3. John D Collins on Jan 16, 2017

    You don’t use the OCF VOR radials for the final approach segment, but would need it for the missed approach segment. In most cases, the DME is going to be channeled by tuning a VOR receiver and you must have simultaneous reception of the OCF DME and the i-OCF localizer, so as a practical matter you will have OCF VOR tuned on a separate receiver. Vectors get you to joining the final approach course, which in this case is the I-OCF localizer and don’t identify FIBUS.

    Of course ATC will be taking the MVA into account. The DVA is used for vectoring below the MVA on departure and does not come into play on an approach.

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