Welcome Guest. Sign in or Signup

3 Answers

VOR or GPS-A @ KSMO

Asked by: 5686 views
Instrument Rating

Why is the KSMO VOR or GPS-A approach so named? The approach course is but 2 degrees from centeline and GPS approaches start from Z and work themselves backwards in the naming sequence.

3 Answers



  1. John D Collins on Dec 22, 2015

    It is named “- A” because it is a circling approach and not assigned to a specific runway. Circling approaches are named starting from the beginning of the alphabet, at “-A”, then “-B” and so on. The Z, Y, X suffixes are used when there is an approach using the same runway and the same means of navigation (ILS, VOR, RNAV, NDB) to differentiate the procedures. They begin at the end of the alphabet and follow reverse order in the alphabet.

    This approach is a circling approach because it ends at the far end of runway 21 or the runway 3 end. It is way too steep to descend from the missed approach point to any specific runway, thus circling to either runway is required. Since it is the first circling approach for the VOR or GPS navigation systems, it starts at – A.

    +2 Votes Thumb up 2 Votes Thumb down 0 Votes



  2. Russ Roslewski on Dec 22, 2015

    John, I think you may have unintentionally misled “lowtimepilot” regarding the missed approach point.

    There is never a consideration to be able to descend and land from the missed approach point, so the steepness of descent from the MAP is not a determining factor in making an approach circling-only.

    There are a few things at work on this procedure which complicate the situation, though.

    One, it’s an old GPS overlay approach, as denoted by the “vor OR gps” naming convention. Thus, it does not comply with current RNAV (GPS) approach criteria. If it did, the MAP would not be permitted to be past the approach end of the runway (but since this is okay on VOR approaches, it carried forward).

    Two, it’s the descent angle required from the FAF to the runway that is one thing used to determine whether a basically-straight-in aligned procedure can have straight-in minimums or not. From 2600 to 177 over about 5.9 nm (estimate) is greater than the maximum allowed for a straight-in approach (400 ft/nm)

    Indicentally, the FAA’s coordination site lists a new RNAV (GPS) procedure to both runways publishing in Sep 2016:
    https://www.faa.gov/air_traffic/flight_info/aeronav/procedures/application/?event=procedure.results&tab=productionPlan&nasrId=SMO#searchResultsTop

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes



  3. John D Collins on Dec 22, 2015

    Russ,

    All true, but the primary point was the naming convention, The approach only has circling minimums.

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.