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7 Answers

Unidentifiable stepdown fix on IAP

Asked by: 1842 views Instrument Rating

Reference: LOC 27R KSFB http://aeronav.faa.gov/d-tpp/1507/00917il27r.pdf   I was flying this LOC APR today and realized that I could not identify PESIY even when I loaded in the approach into the GPS (G1000). There are no other radials to identify PESIY, so I just used the non-step down minimums. What got me questioning was seeing the fix on the moving map display. The chart database knows its location, but the approach database does not. Is this normal?

7 Answers



  1. John D Collins on Jul 15, 2015

    Drew,

    The approach chart provides the information to identify PESIY, just not by name in the approach database sequence. You do not need to use the approach database at all to fly this approach, but if you do, it is only providing you with situational awareness information. You can identify PESIY by using your along track distance from the runway of 1.4 NM. You can also manually tune the approach and do a direct-to PESIY, or you can do a direct-to I-FNU which would read 3.4 NM.

    It is common practice to not include in the approach database the step down fixes on a localizer approach that is also has a full ILS option. Most will use the along track distance to the runway threshold as it is displayed on most GPS systems including the G1000, you just have to do the math in your briefing so you can identify the fix location.

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  2. Drew on Jul 15, 2015

    I just want to make sure: wouldn’t I need the GPS approach database (assuming I’m not getting identification from radar) since it is noted that “GPS or radar is required”? All other solutions you mention require the GPS.

    I was wondering why it would list GPS as a required equipment if it didn’t provide me with anything helpful. I was simply using it wrong. Thank you, John.

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  3. Wes Beard on Jul 15, 2015

    You can also identify PESIY using DME off of the localizer frequency. I’m assuming there was no DME in your airplane.

    I haven’t flown a Garmin GPS in awhile but other GPS’s have both the ILS and LOC approaches as selectable approaches. One of the differences is that LOC approaches have fixes inside the FAF shown while the ILS does not.

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  4. Russ Roslewski on Jul 16, 2015

    It’s all about the placement of the note. Since this note is in the planview, it means that GPS or RADAR is required for procedure entry. And look at the ways to enter this procedure – you either get radar vectors OR you arrive via a GPS waypoint (VOFOS or GACNO), so the note is correct. You do NOT need DME to fly the final approach segment either as an ILS or a LOC (so it’s not a LOC/DME), but you do need DME (or a suitable GPS receiver) to identify PESIY to get the lowest minimums.

    The verbiage is in AIM 5-4-5a3(b):

    (b) In some cases, other types of navigation
    systems including radar may be required to execute
    other portions of the approach or to navigate to the
    IAF (e.g., an NDB procedure turn to an ILS, an NDB
    in the missed approach, or radar required to join the
    procedure or identify a fix). When radar or other
    equipment is required for procedure entry from the
    en route environment, a note will be charted in the
    planview of the approach procedure chart
    (e.g., RADAR REQUIRED or ADF REQUIRED).
    When radar or other equipment is required on
    portions of the procedure outside the final approach
    segment, including the missed approach, a note will
    be charted in the notes box of the pilot briefing
    portion of the approach chart (e.g., RADAR
    REQUIRED or DME REQUIRED). (more text cut out)

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  5. Drew on Jul 16, 2015

    Thank you for the additional feedback.

    Russ, according to the AIM, wouldn’t “DME REQUIRED” be noted in the PESIY minimums or in the approach note section? I often see something like “dual VOR required” for stepdown minimums when cross radials are used to identify a fix; however, in this case, nothing is noted, even though either a DME or GPS in lieu of DME is required. Maybe it’s a design mistake?

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  6. Russ Roslewski on Jul 16, 2015

    No, because DME is not required to fly the final segment of the approach. You can fly the LOC perfectly fine without DME, you just won’t get as low as you like. So it’s not “required”. If you can identify PESIY you can descend further, but you can do that any legal way (DME or GPS in this case). The wording requirements have changed over the years, so when you see one approach worded one way and another worded a different way, it is usually just because the chart hasn’t had a major amendment in a while.

    This is one reason why good preflight planning includes looking at the expected approaches at your destination, so you don’t have to do all that careful reading in the air. I have even gone so far as to circle or highlight (or the iPad equivalent) which MDA I am going to use based on equipment and aircraft category, before the flight, so there’s no confusion once I get there.

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  7. Drew on Jul 16, 2015

    Thanks for the clarification, Russ.

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