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Thread: IFR flight limitations

  1. #1

    IFR flight limitations

    What are the items that an external GPS navigator (a la GTN650) can do that the AFS PFD cannot do?

    My understanding is it has a WAAS GPS, has all the waypoints, ect.

    Is it missing integrity monitoring and GPS approaches?

    Could one (legally) fly an IFR flight plan using the internal flight plan in the EFIS and then switch to the external GPS navigator just to fly the approach?

    -Craig

  2. #2
    Quote Originally Posted by cdeggz View Post
    What are the items that an external GPS navigator (a la GTN650) can do that the AFS PFD cannot do?

    My understanding is it has a WAAS GPS, has all the waypoints, ect.

    Is it missing integrity monitoring and GPS approaches?

    Could one (legally) fly an IFR flight plan using the internal flight plan in the EFIS and then switch to the external GPS navigator just to fly the approach?

    -Craig
    A certified IFR GPS navigator will have approach data that is not available on your PFD. Integrity checking is a function of the GPS, not the EFIS. Some of the non-certified GPS are pretty accurate, but they are missing the obvious TSO certification to be legal for IFR and don’t have the required data for flight planning and approaches.

    I have an AFS GPS that is my backup. I also use it occasionally just to makes sure it still works. I tend to use the AFS GPS with an internal flight plan when heading to a local private grass strip. Garmin doesn’t include private grass strips in the database for the GTN-650.

    The internal flight plan function is very feature rich, but it doesn’t have any of the approach data. I.e. no glideslope information or procedure turns, etc. With the AFS (or Dynon) GPS you could fly a GPS approach using the step down altitudes off the approach plate in an emergency, but that’s not legal. I also would even think of doing that if the ceiling and visibility is near minimums. However, I find that it’s easier to program my flight plan into my GTN-650 for all IFR flights. IFR navigators will pass all the required data to your EFIS via the Arinc connection. The rs-232 connection is primarily lat/long position information. You can use the internal EFIS flight plan for enroute, but you are going to have to use your IFR navigator for the approach. You don’t want to be fiddling changing from internal to the IFR navigator at the critical time of transitioning to the approach. That’s a distraction you don’t need.

    If you are flying VFR, entering flight plans in either location works just fine.
    Bob Leffler
    N410BL - RV10 - Flying
    http://mykitlog.com/rleffler

  3. #3
    Quote Originally Posted by rleffler View Post
    but they are missing the obvious TSO certification to be legal for IFR
    I was understanding in an experimental a TSO certification is not required for this, just needs to hit TSO specs.

  4. #4
    Quote Originally Posted by cdeggz View Post
    I was understanding in an experimental a TSO certification is not required for this, just needs to hit TSO specs.
    You’re correct. But name a non-TSO certified navigator that provides all the approach data. Also, while a device may meet the TSO specs, how do you prove it. No vendor will say that for liability reasons.

    No issues if all you fly is VFR. But if I’m flying in IMC, I’m using a certified navigator.
    Bob Leffler
    N410BL - RV10 - Flying
    http://mykitlog.com/rleffler

  5. #5
    What external GPS manufacturer offers IFR approach capability on an external navigator? Very stringent specifications have to be met for that. Theoretically you could also use the AFS Internal Flight Plan and fly an approach using the HITS feature but nobody at AFS will would pat you on the back and say that’s a great thing to do - quite on the contrary they will do the opposite. Bottom line is if you want to fly IFR in IMC there are certain rules you are going to have to stick to and that’s a good thing!

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