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2 Answers

Why don’t some NPAs have VDPs?

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Airspace, Instrument Rating

Is there a criteria?

2 Answers

  1. John D Collins on Mar 12, 2015

    Yes. The basic criteria for a VDP is that the approach have straight in minimums. The visual segment between the VDP location and the threshold is evaluated for obstacles on both a 34 to 1 and a 20 to 1 basis. Penetrations of the 34 to 1 surface affect visibility requirements. The 20 to 1 affects several things, including whether a VDP is published or not. A VDP is not published if the 20 to 1 visual surface is penetrated by an obstacle. Also, if a remote altimeter source is used, the VDP is not published.

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  2. Russ Roslewski on Mar 13, 2015

    There are a few other reasons to not publish them as well, although John got the most common ones.

    – If the VDP would be located prior to a stepdown fix.
    – If the VDP would be located after the MAP.
    – If the VDP would be within 0.5 of another fix in final.
    – If there is no way to mark the VDP location (i.e. if it’s a VOR/LOC/NDB approach, DME must be available).

    Source for this is FAAO 8260.3B, para 253.

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