G5 ILS trouble

Discussion in 'Avionics and Upgrades' started by DesertNomad, Jun 11, 2019.

  1. DesertNomad

    DesertNomad Pattern Altitude

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    I have a GTN750 and dual G5s, hooked to an STEC-30 AP. On a GPS approach, everything works as expected but today flying an ILS approach, I first tuned the ILS frequency (110.9) in the 750, then selected and activated an ILS approach (16R X at KRNO) and got what looked like a back course ILS arrow but no glide slope. The arrow was green and LOC was selected on the CDI button of the 750. The needle was pointing down and the R/L of course line seemed to be working.

    On the GNC255 hooked to a mechanical CDI, I got both needles. What Am I doing wrong to get the ILS working right on the G5. It has worked before but I have also run into this before where no glideslope appears.
     
    Last edited: Jun 11, 2019
  2. Ryan Klems

    Ryan Klems Pre-takeoff checklist

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    Did you have your course set to the front range inbound course ? If you happened to have the course left from a prior approach that diverged from the inbound heading > a certain number of degrees, it decides you are doing a back course and disables the glideslope and triggers reverse sense on the needles.
     
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  3. DesertNomad

    DesertNomad Pattern Altitude

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    Quite possibly. With a traditional CDI, no action is needed on the heading dial. Do I need to manually set the G5 to the inbound course of the ILS (164 deg in this case).
     
  4. Ryan Klems

    Ryan Klems Pre-takeoff checklist

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    Yeah, a back course gets false glideslopes, so the G5 (and other electronic instruments like the G500/G3X/etc) will suppress any glideslope indication when it thinks you are on the back course (as well as reversing the displayed course corrections, to avoid having your brain need to do the work). It's good practice to always set the course in the CDI (even on the older mechanical ones where course on the LOC generally doesn't have an effect).
     
  5. DesertNomad

    DesertNomad Pattern Altitude

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    Yeah - I do put it the course on the mechanical CDI - makes sense to do it on the HSI too - I'm new to the G5 so bit of a learning curve.
     
  6. WannFly

    WannFly En-Route

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    May be a back course thing, in my setup if I am flying ILS I don’t have to touch the G5, haven’t flown back course yet.
     
  7. DesertNomad

    DesertNomad Pattern Altitude

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    I would think that when you load an approach and start to fly it (cross the IAF for example), the course needle should automatically adjust to the inbound heading of the ILS, but it doesn't seem to do that. In My case I was on a 164 inbound heading on the ILS, but my Course setting on the G5 HSI was 320 from a previous approach so it assumed I was flying the back course (never mind that I was going the wrong way to do that).
     
  8. WannFly

    WannFly En-Route

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    thats odd. it should automatically do that in G5, at least mine does from 480
     
  9. BrianNC

    BrianNC Pattern Altitude

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    @DesertNomad You should post your OP on BeechTalk.com (if you haven’t called them directly). A couple of Garmin reps are active there and should see your post.
     
  10. DesertNomad

    DesertNomad Pattern Altitude

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    I have and was told basically the same thing - that I need to set the inbound course. It seems strange that it won't do this automatically since the approach surely knows the inbound heading.
     
  11. bnt83

    bnt83 Final Approach PoA Supporter

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    I think automatically turning the course to the ILS is called auto slew, the G5 does not do that. So you need to manually set it.
     
  12. N1120A

    N1120A Line Up and Wait

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    The G5 will automatically set the course, but only under certain circumstances. I've noticed that if you are flying in VLOC and load the approach then, you'll need to manually set. If you are flying in GPS, loading the approach should automatically set the course, once you switch to VLOC, to the ILS. You do need to double check it though. When flying a G5 airplane, I'll load the approach and do a quick swap over after from GPS to VLOC to see that the course is properly set, then go back to GPS for headings until I get turned onto the localizer.
     
  13. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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    @DesertNomad have you had a chance to try again, and did setting the course yourself help?

    I just went through training on a G1000 airplane, and was somewhat surprised to find that it defaults to backcourse mode if you turn on from more than 105º off the FAC, or something like that... So, definitely worth checking. Let us know what you learn!
     
  14. bnt83

    bnt83 Final Approach PoA Supporter

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    I flew with them the Saturday, the sequence of events: (GTN650 on v6.51 and G5s on v6.00)

    • Load and activated ILS 31 to KYKN
    • Hit direct to UCAVO tuned the VHF Nav to ILS frequency. The direct-to UCAVOvia GPS snaps the G5 HSI to the correct course automatically. (I'm still 20 miles west or so at this point)
    • When I arrived at UVACO the CDI switching automatically changed to VHF from GPS, I turned about 270 degrees to the right to intercept the LOC, HSI course had to be manually set.

    upload_2019-6-17_6-43-50.png
     
  15. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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    What was the HSI course before you manually set it?
     
  16. bnt83

    bnt83 Final Approach PoA Supporter

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    I don't recall exactly but it had to be around 110.
     
  17. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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    So, on GPS... I guess I'm just wondering why the G5 doesn't get the final approach course for the ILS from the GTN like it does the rest of the time.