Offset LOC at KSGJ

Discussion in 'Cleared for the Approach' started by John777, Nov 25, 2016.

  1. John777

    John777 Pre-takeoff checklist

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    I am attaching a link for ILS/LOC DME 31 approach into KSGJ.
    If you look into chart, you will notice the the word offset 1.23degrees which means course is not aligned with the runway.

    Also in the margin section of the chart, mentions Alternate Not authorized.
    I am guessing the ILS is not authorized for being offset, is there any other reason why it is not published for filing as alternate?

    John.
     
  2. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    Usually, the issue with alternate NA is that the navaid involved lacks sufficient monitoring.
     
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  3. John777

    John777 Pre-takeoff checklist

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    I just noticed from the Alternate minimum for the airport that VOR approach into teh airport will be NA if tower is closed. Not sure why VOR appraoch is only mentioned in there.
     
  4. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    Could be the ILS lacks monitoring at any time. The VOR may only be monitored by the local tower.
     
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  5. John777

    John777 Pre-takeoff checklist

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    So, it is the monitoring issue.
    Happy thanksgiving Flyingron, thanks for your comments.
     
  6. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    Actually, the other approaches probably aren't authorized for alternate when the tower is closed because the tower also provides the weather reporting (no AWOS). The VOR is probably monitored by some other (approach/center). The ILS probably isn't monitored at the required level, period.
     
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  7. MAKG1

    MAKG1 Touchdown! Greaser!

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    If the offset were big enough to matter for anything, it would be an LDA rather than a LOC.

    1.23 deg is tiny. On an 8000 foot runway, the error at the threshold would be around 120 feet, less than the runway width.
     
  8. aterpster

    aterpster Pattern Altitude

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    The max offset for an ILS or LOC is 3 degrees.