With more instrument approach procedures being designed for RNAV/GPS equipped aircraft, and considering the high level of radar coverage currently available, is there a need to spend much valuable training time teaching students the skills and techniques for flying an approach using a DME arc?

  • $\begingroup$ Our local DPE always has the candidate fly a DME arc around a terminal VOR as part of the practical test—usually with partial panel. It can be quite challenging, especially if there is a strong wind. $\endgroup$ – JScarry Jul 27 '17 at 17:08
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    $\begingroup$ Yes, of course. Flying arcs is a core instrument procedure that teaches students how to handle multiple tasks at once (to say nothing of the practical applications). I'm disappointed NDBs are being phased out. GPS is great and all, but basic compentencies must be mastered...or at least be understood. $\endgroup$ – acpilot Jul 28 '17 at 5:04
  • $\begingroup$ Interesting comments and I don't have a firm position one way or the other. But, consider that there are relatively few approaches with a DME ARC (in U.S.). But there are 14,300 lines of minima for RNAV/GPS approaches and only 1,550 ILS lines of minima. Also, there are LDA/DME, LOC/DME BC, SDF, Side Step, LOC/NDB approaches, etc. Instructors can't provide training in every possible approach before obtaining an instrument rating. FAA says evaluators should select approaches for test applicant is likely to use. Can't train on everything prior to obtaining an instrument rating. $\endgroup$ – 757toga Jul 28 '17 at 14:23
  • $\begingroup$ Continuing from above: This is not, of course, to say that prior to flying a particular approach, the pilot should not be adequately trained on that type of approach. There are many operational procedures that a pilot will have never received training on prior to obtaining a particular certificate or rating. It's a responsibility of the pilot to obtain additional training (post certificate or rating) prior to conducting some new procedure (IFR or VFR). $\endgroup$ – 757toga Jul 28 '17 at 14:27

Apart from the fact that it is required to learn, the obvious "benefit" is that you know what to do when flying to an airport that uses a DME Arc approach. RNAV/GPS approaches are becoming more common, but have far from taken over from conventional approaches. Even if an airport has radar, it does not necessarily mean that radar vectoring for final approach course is available - consider, for example, uncontrolled airports. Here is an example of a DME Arc approach still in use today, at an uncontrolled airport in Denmark that does have radar, but no radar vectors are provided (since it is uncontrolled):

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And an example from Norway:

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(images from AIP Denmark and AIP Norway respectively)

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    $\begingroup$ The KMTN VOR/DME 15 approach is a somewhat well-known one in the US; even the final approach course is an arc. $\endgroup$ – Pondlife Jul 27 '17 at 17:23
  • $\begingroup$ @J. Hougaard. Good discussion. However, one point in your response needs follow-up. Specifically, referencing you example airport in Denmark that has radar, but no radar vectors are provided since it's "uncontrolled." Perhaps in some parts of the world this might be true. However, in the U.S. whether or not an airport is controlled or uncontrolled is not related to availability of ATC to provide radar vectors if the coverage exists. See, for example, KMTO (in Illinois). $\endgroup$ – 757toga Jul 27 '17 at 18:09
  • $\begingroup$ @757toga There is no ATC at this specific airport, only AFIS. The AFIS operator makes use of radar. It is a very fundamental rule that it is not allowed to provide radar vectors in uncontrolled airspace, and without checking the rules I am fairly certain you can't do that in the USA either. Maybe the airport to which you are referring has controlled airspace above it, but the airport itself is uncontrolled? $\endgroup$ – expeditedescent Jul 27 '17 at 20:00
  • $\begingroup$ @J. Hougaard.apparently we are talking about two different things. When you say, in your example "uncontrolled airport" (i.e. airport in uncontrolled airspace), I wasn't aware you were saying all of the airspace above the airport is uncontrolled airspace (i.e. G airspace). Sounded like you just meant the airport itself. In the U.S., for most airports in Class G uncontrolled airspace, controlled airspace begins at 700 or 1200 agl. This is the case with KMTO (E airspace begins at 700). The radar vector to join the approach occurs in Class E (controlled space). $\endgroup$ – 757toga Jul 28 '17 at 0:05
  • $\begingroup$ @J. Hougaard At what altitude above Sonderborg airport (above) does "controlled" airspace begin? $\endgroup$ – 757toga Jul 28 '17 at 0:07

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