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GPS Circling Approach Criteria

Asked by: 2727 views Airspace, Instrument Rating

The AIM states, "Straight-in Minimums are shown on the IAP when the final approach course is within 30 degrees of the runway alignment (15 degrees for GPS IAPs) and a normal descent can be made from the IFR altitude shown on the IAP to the runway surface. When either the normal rate of descent or the runway alignment factor of 30 degrees (15 degrees for GPS IAPs) is exceeded, a straight-in minimum is not published and a circling minimum applies."

Freeway Airport (W00) has an RNAV 36 approach with a final course alignment offset by 16.76°, which seems to go against the AIM's note. This appears to be potentially due to the prohibited area west of the field. However, there is an even more extreme example with the RNAV 15 into Kingston-Ulster Airport (20N), with a 29.15° offset, with no SUA around it.

Is there a source document for allowing for such exceptions?

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1 Answers

  1. Best Answer


    John D Collins on May 01, 2021

    The AIM wording is not the authority for this and appears to be incorrect. See FAA order 8260.58B RNAV TERPS. Section 3-2 General Non-Vertically Guided Final Segment, 3-2-2 Alignment states in part:

    “a. Straight-in with offset alignment. When the final course must be offset, it may be offset up to 30 degrees (published separately from vertically guided) when the following conditions are met:
    1. Offset ≤ 5 degrees. Align the course through LTP.
    2. Offset > 5 degrees and 10 ≤ degrees. The course must cross the runway centerline
    extended at least 1500 feet prior to LTP (5200 feet maximum).
    3. Offset > 10 degrees and ≤ 20 degrees. The course must cross the runway centerline extended at least 3000 feet prior to LTP (5200 feet maximum). For offsets > 15 degrees, CAT C/D minimum published visibility 1 SM, minimum height above touchdown (HAT) of 300 feet.
    4. Offset > 20 to 30 degrees (CAT A/B only). The course must cross the runway centerline extended at least 4500 feet prior to the LTP (5200 feet maximum).”

    LNAV/VNAV must be aligned within 15 degrees and LPV must be aligned within 3 degrees.

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