GTN 650, CDI, and Direct-To

Discussion in 'Avionics and Upgrades' started by Harry, Dec 31, 2018.

  1. Harry

    Harry Filing Flight Plan

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    I have a GTN 650 connected to a Garmin GI-106A CDI. Let's say I want the CDI to track the course from my present position to some waypoint. Hitting Direct-To for that waypoint doesn't work; the CDI reflects the track to that waypoint from the previous waypoint, not my present position.

    The manual says "The VLOC receiver must be selected for display on the external CDI/HSI for approaches which are not approved for GPS". But I have the GTN in GPS mode, not VLOC mode, since I'm trying to go direct-to a GPS waypoint. I haven't tried doing this in VLOC mode, but I don't see why it would work.

    Any ideas &/or clarification?
     
  2. Ravioli

    Ravioli Final Approach PoA Supporter

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    In 430 speak I think you need FPL > Activate Leg
     
  3. Unit74

    Unit74 Final Approach

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    Load the Direct To, switch over to the flightplan page and show us what it says.
     
  4. chemgeek

    chemgeek Line Up and Wait

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    This is why I wrote for myself a cheat sheet and keep it in the airplane. Depending on exactly how you want to do this, these are the various ways of getting direct-to on a GNS-430. I assume the knobology on the GTN is similar, although there should be a way to do it via touchscreen as well. This is a portion of my GNS-430 cheat sheet that is always on my clipboard. In GNS-speak, the key sequence is some version of Direct-to/Enter/Enter. The second item is how to re-center the CDI from your current position.

    Direct-to Waypoint
    · Direct-To
    · Enter waypoint with small and large knobs
    · Enter-Enter

    Re-center CDI to Active Waypoint
    · Direct-To
    · Enter-Enter

    Direct-to Non-active Waypoint
    · Direct-To
    · Large knob to select FPL
    · Small knob to select waypoint
    · Enter-Enter

    In any case, if you are doing this to a GPS waypoint, you need to be in GPS, not VLOC mode.
     
  5. Harry

    Harry Filing Flight Plan

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    OK, I know how to do direct-to for waypoints in the flight plan, and ones that aren't — on the GTN, you hit Direct-to (physical button), select a waypoint, then hit D->Activate (on-screen)

    But you're saying that once I've done that, then I do it again with the direct-to waypoint I just set, and that centers the CDI at my current position? I'll try it, but it sounds odd.
     
  6. Harry

    Harry Filing Flight Plan

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  7. Blatham489

    Blatham489 Pre-takeoff checklist

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    sounds to me like you’re doing it right. Either there’s a problem with your CDI or you’re misinterpreting what it’s saying (most likely solution).

    Try posting some pics of what you’re experiencing next time you’re up showing the flight plan, default nav and your CDI.
     
  8. Harry

    Harry Filing Flight Plan

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    New theory (until I get a chance to go to the plane): If I have a flight plan active, the CDI is always going to reflect the route between the previous and next waypoints regardless of where I am when I hit direct-to. In other words, if my flight plan shows a route from A->B, with B as the next waypoint, if I'm at point C when I hit direct-to, the CDI will show the line from A-B, ignoring C.

    If this is correct, then I could either a) delete the flight plan (or not set one up at all) and just use direct-to; or b) delete the previous (or all previous) waypoint(s) from the flight plan before doing direct-to.

    Will report back!
     
  9. Walt

    Walt Pre-takeoff checklist

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    I have a 750 in my airplane. When I have a flight plan entered but center says cleared direct I push the direct to button, enter the waypoint I am cleared to then push activate. The 750 keeps the flight plan in the background but navigates directly to the "direct to" waypoint. Your 650 should do the same thing although the button pushing maybe a little different.
     
    flyingcheesehead likes this.
  10. midlifeflyer

    midlifeflyer Final Approach

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    No. As @Walt said, entering a "Direct To" will send you from your present position direct to the waypoint you entered. Regardless whether you ave a flight plan entered or not. Check out my video on entering a waypoint not already in the flight plan in the GTN650. It was created to be simple, but it works the same with a more complex flight plan.
     
  11. eman1200

    eman1200 Touchdown! Greaser! PoA Supporter

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    don't know if it was just me but there was no sound.

    the last flight I took I wanted to enter a 'direct to waypoint' into an existing flight plan instead of just direct to. not sure why, as direct to takes fewer 'clicks' and I'm all about less clicks, and also entering direct to still keeps your flight plan but I just wanted to try it this way. worked fine, just a coupl'a extra clicks.
     
  12. midlifeflyer

    midlifeflyer Final Approach

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    There's no sound. There's even a negative comment about it. I did a number of short ones like this in response to a question on a forum so I wen't with quick and easy rather than getting into narration. Probably a mistake. (I'm going to try to do better in the future - get used to narrating "on the fly" so to speak)

    On your point, I have a (slightly) better one. Still no sound, but there is scrolling text to describe. It shows amending a flight plan with a new waypoint using D→ to get going right away, and the entering it into the flight plan at your leisure. It's probably also a better illustration of @Harry's dilemma.

     
    Last edited: Jan 1, 2019
  13. Harry

    Harry Filing Flight Plan

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    Again, I'm not asking how to do direct-to; I know how to do it. The question is what the connected CDI does when I do it.

    My theory is that when there's an active flight plan, the CDI will show where I am with respect to the path between two published waypoints — the last and the next ones in the flight plan. So it wouldn't center unless I happened to be on that path already.

    If there isn't an active flight plan, I'm guessing that the CDI would immediately center, tracking a line from my present position to the direct-to waypoint.

    H
     
  14. midlifeflyer

    midlifeflyer Final Approach

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    Some of this is going to be depenent on your setup - OBS/CDI or HSI; GPSS or not - but generally...

    The connected CDI will send you to the Direct To waypoint. The CDI being fed by the GPS only knows what the GPS is feeding it and that's the Direct To waypoint. Doesn't mater if there is an active flight plan or not.

    Here's the CDI from my second video after going D→ VAN, leaving the flight plan intact. An external CDI will show the same.
    temp.PNG

    I don't know, but what you may be seeing is that the external OBS does not twist itself to the new course. In most installations, it will act like a localizer - the needle is independent of the OBS. But, just like with a LOC, it's better to twist it to your reference course, and the GPS may well annunciation its recommendation to make the change.
     
    Last edited: Jan 1, 2019
  15. chemgeek

    chemgeek Line Up and Wait

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    Direct-to enter enter should re center the CDI to the active waypoint from your current position and should update the magenta line on the map display. If the track is sufficiently different, you should get a message to reset the bearing on the CDI, although it is for advisory purposes only in GPS mode. That's the way it works on the 430 anyway. The CDI should reflect your deviation from the magenta line desired track established. If the track doesn't change when you execute a direct-to the active waypoint there may be some problem with the arming sequence. This is a pretty common in flight task.
     
  16. chemgeek

    chemgeek Line Up and Wait

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    From the GTN-650 cockpit manual:

    Direct-to
    FPL tab
    Select waypoint
    Activate

    Track should adjust direct to selected waypoint, and CDI should reflect track error from the new course.
     
  17. midlifeflyer

    midlifeflyer Final Approach

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    Also on the GTN, G1000, Avidyne IFD,....
     
  18. Harry

    Harry Filing Flight Plan

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    OK, obviously I need to go try this again and confirm the behavior.
     
  19. DGlaeser

    DGlaeser Pre-takeoff checklist

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    Entering a 'new' Direct-To waypoint when you have an existing active Flight Plan will usually confuse Garmin (any of their units - I've done it on the G1000 a few times).
    So you are correct - get rid of the existing flight plan, then go Direct-to an entered waypoint.
    If you have a flight plan, you can select any waypoint on your flight plan and to Direct-To.
     
  20. eman1200

    eman1200 Touchdown! Greaser! PoA Supporter

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    hhhmmm, I thought the garmin kept the flight plan with a direct to entered so if u cancel the direct to it keeps the FP? seems like a good feature, I'm not sure I'd get rid of the flight plan.
     
  21. midlifeflyer

    midlifeflyer Final Approach

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    If I were changing my destination, sure, I'd get rid of my flight plan (eventually). But for an intermediate off route waypoint, such as in an amended clearance or temporary deviation, that seems like a lot of extra work for no reason.

    If I recall correctly, some early units would wipe out the existing flight plan with a Direct To, but I haven't seen that behavior in years. guess I haven't seen the "Garmin confusion" you have.
     
  22. Harry

    Harry Filing Flight Plan

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    I'm hoping Walt's trick works — i.e. don't choose your direct-to waypoint from the flight plan.
     
  23. DGlaeser

    DGlaeser Pre-takeoff checklist

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    Haven’t tried going to a waypoint not on the flight plan in quite a while. Sounds like the latest s/w acts as expected. That is a good thing :)
     
  24. midlifeflyer

    midlifeflyer Final Approach

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    Check it out, Harry, it really doesn't matter.

    If the waypoint is already in your flight plan, tapping on it in the GTN and telling it to go directly there will send you directly there.
    If the waypoint is not already in your flight plan, adding it to the flight plan and telling the GTN to take you Direct To it will send you directly there.
    If the waypoint is not already in he flight plan, separately going Direct To will send you directly there (but if yo need it for your flight plan, you'll need to put it there afterward.

    Three ways to accomplish the exact same thing. And the CDI will follow.

    You might want to get with a CFI who understands the system for a short lesson.
     
  25. chemgeek

    chemgeek Line Up and Wait

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    Typically, the Garmin boxes will do the same thing a bunch of different ways. I guess one piece we are missing here is whether OP wants to activate a Direct-To toward an existing waypoint in the flight plan, or a waypoint not in the current flight plan. The arming sequences are slightly different.

    To go to a new (not in flight plan) waypoint, Direct-To, select a new waypoint, then Enter (Activate). A new track from current position to the entered waypoint should be displayed, and the CDI should key to this new track. The flight plan should be unaltered (and sidelined). The Direct-To waypoint is held in a separate buffer while you are navigating Direct-To. You can go back to the flight plan at any time.

    To go to an existing waypoint, there are a couple of options (on the 430): Direct-To, large knob to select the FPL field, then select the desired existing waypoint in the flight plan using the small knob; OR, FPL, large knob to select the desired flight plan waypoint, then Direct-To, Enter, Enter (Activate). A new track from current position to the desired waypoint should be displayed, and the CDI should key to this track. NOTE: if you mess this up by pressing Direct-To, Direct-To, Enter instead, you will activate the flight plan leg to that waypoint instead, and the track will be used between the prior waypoint and the selected one. (This is a useful sequence to activate a later leg in a flight plan after initial ATC vectors or a short cut to rejoin an airway farther down the line, but I digress.)

    If the OP is not getting the appopriate Direct-To track displayed--first thing to check on the map display after arming Direct-To--then there may be a knobology/tapology sequence issue in activating the desired Direct-To track. If the new Direct-To track is displayed but the CDI is not responding to it, there is some other issue, but I can't imagine how that can happen, since the CDI should be simply deriving cross-track error from active GPS course, unless VLOC or OBS is selected.

    Perhaps a good way to test the knobology/tapology sequence is to use the GTN simulator to see if it behaves as you expect. The GNS simulator is pretty good at exploring the knobology of the GNS430W, except that the nav database is way out of date. All the various Direct-To options above work as expected in the GNS430W simulator, and to my knowledge, in my aircraft unit as well. It's little stuff like the difference between Direct-To Enter Enter and Direct-To Direct-To Enter, or where does an inserted waypoint go in the flight plan (before or after the current waypoint?) that will drive you crazy when you are bouncing around in flight trying to amend your track or flight plan. Hence a one page common GNS430 task sheet on my clipboard--it's a lot quicker than opening up the flight manual.
     
  26. midlifeflyer

    midlifeflyer Final Approach

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    BTW, the "early units" I mentioned were not GTNs. They may have been early GNS or maybe even before that. They wanted you to enter the new waypoint directly into the flight plan or it was treated as a new flight plan. Not sure, but I think they ultimately realized it was more efficient to be able to get started in the right direction and then add it to the flight plan.
     
  27. midlifeflyer

    midlifeflyer Final Approach

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    The GTN and the G1000 do it exactly the same way as you describe for the GNS.
     
  28. Harry

    Harry Filing Flight Plan

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    OMG… would you please read my posts carefully before replying? Thank you.
     
  29. midlifeflyer

    midlifeflyer Final Approach

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    Sorry. What did I miss?
     
  30. Harry

    Harry Filing Flight Plan

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    Got it, that's what I was looking for (and theorizing).

    Yep, I've been doing that. The only thing it doesn't do is show an external CDI. Someone mentioned that it should show the same as the GTN's 'CDI' display. I'll check that out in the plane this weekend.

    Thanks all for the help!