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ILS ADF Requirement: Why?

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Flight Instructor, Instrument Rating

I'm studying for my instrument rating, and an airport where I've been practicing (KSTC - Saint Cloud, Minnesota) has an ILS approach for 31 (http://204.108.4.16/d-tpp/1110/05799IL31.PDF). The approach has the standard OM, and also has an LOM at the same location, which seems to be fairly typical.

What I don't understand is why the approach plate indicates, "ADF REQUIRED." With an outer marker, why would the approach require this? It's not needed for knowing the outbound course, since the localizer and outer marker would seem to tell you everything you need to know to fly it. What am I missing?

1 Answers

  1. Best Answer


    Eric Gideon on Sep 27, 2011

    It’s required for the missed approach, which has the pilot climbing straight ahead to 3000 feet before initiating a left turn direct the ST NDB or HUSSK intersection, where the hold is executed.

    In this situation GPS can be substituted for ADF.

    Very often the requirements on the procedure are not there as requirements to successfully land from an approach – they’re to ensure your safety if and when you are unable to complete it.

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