GPS or Vloc VOR DME approach on checkride

Discussion in 'Cleared for the Approach' started by obelix, Dec 18, 2016.

  1. obelix

    obelix Pre-Flight

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    If I'm going to shoot a VOR-A DME approach to an airport. I load the approach and IAF into the 430. Lets say the IAF is the VOR. I can think of two ways to shoot the approach, just want to verify which is the acceptable one for the check ride.

    #1) Track inbound to the VOR via VLOC with the CDI, perform the procedure turn, fly to the IAF/VOR. Start the timer once I go to/from. Time all the way down to the Altitude/MAP at 90knots staying on the VLOC CDI and go missed once my timer reaches 3:30.

    #2) Track inbound to the VOR via GPS with the CDI, perform the procedure turn, fly to the VOR. Waypoint changes to the Missed appoach. Fly all the way down to the Altitude/MAP at 90knots saying on the GPS CDI and go missed once I see the distance to the MA reach 0.

    I'm guessing that #1 is the one that he wants to see, but aren't both perfectly fine?
     
  2. JimNtexas

    JimNtexas Pattern Altitude

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    If it is a VOR/DME then you should use DME or approved GPS.
     
  3. obelix

    obelix Pre-Flight

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    I'm getting DME from the GPS. They are the same device in this case. So scenarios 1 and 2 both still apply.
     
  4. tsts4

    tsts4 Pre-takeoff checklist

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    No. You can't do number 2 the way you describe it. If you are using GPS, at some point once inbound to the VOR FAF you have to switch the Nav source to VOR/LOC.

    Which approach?
     
  5. James331

    James331 Touchdown! Greaser!

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    Well you can do #2, but you need to use another nav head/screen/whatever to monitor the real VOR signal, I'd watch the clock as well as the MAP on the GPS, even though real world the GPS MAP is going to be more precise than the clock and TAS.

    Actually I can't recall the last VOR I've shot, ILS, tons of GPS, even a few NDB from the GPS overlay, while monitoring of course, VOR, been ages.

    Only thing most pilots don't shoot via the overlay is a ILS/LOC.
     
  6. KA550

    KA550 Pre-takeoff checklist

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    Who is the PIC on the checkride?
     
  7. obelix

    obelix Pre-Flight

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    KMAC - VOR-A

    What's the point of actually using the VOR, the GPS will track the FR radial same as the NAV. Why wouldn't both be acceptable?
     
  8. tsts4

    tsts4 Pre-takeoff checklist

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    Unless it has GPS in the title, you can't use it for Nav on the final segment. You have to use a valid VOR signal. Now using GPS to determine the MAP off the VOR is legal.
     
  9. obelix

    obelix Pre-Flight

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    The scenario that I'm thinking of here that might happen is that I'm not at the FAF yet and he covers the GPS which has my DME. In that case, I'm thinking that I can track the TO radial to the VOR, turn etc, but without the GPS I have no DME.

    In that case, is using the switch of TO/From to start the MAP timer acceptable? It would also make finding my missed hold fix impossible if that is based off of DME from the FAF/VOR.
     
  10. tsts4

    tsts4 Pre-takeoff checklist

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    Yes as to starting your time to the MAP at the flip. Your hold fix can be determined one of two ways; DME off of MCN or the cross radials of MCN and DBN. If you really think you'll lose your GPS then you might want to practice a bit finding a fix and flying a hold off of that fix using crossing radials. If you only have 1 VOR it's a bit of work but doable with a little practice.
     
  11. obelix

    obelix Pre-Flight

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    Good point.. I didn't really look close at the missed hold fix, but that would work. Generally I wasn't sure if it was legal to shoot a VOR approach without DME if he had failed it. As you mention should be possible to shoot the approach without any DME, just not sure if it's legal to do so.
     
  12. tsts4

    tsts4 Pre-takeoff checklist

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    It's only a problem if the approach says DME is required. In the case of the VOR-A in your example DME (and of course GPS as a suitable sub) is not required, just nice to have as either would make the approach easier to fly.
     
  13. azure

    azure Final Approach

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    Where the heck is KMAC? Or was that a typo? A search for it in ForeFlight fails...
     
  14. tsts4

    tsts4 Pre-takeoff checklist

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    KMAC--Macon, GA
     
  15. azure

    azure Final Approach

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    Thanks. Search for KMAC is working now, but for some reason failed earlier for me... three times in a row in fact.
     
  16. JimNtexas

    JimNtexas Pattern Altitude

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    I would use DME or an approved GPS as the primary method for identifying the fixes by distance from the VOR. You can backup with timing, that won't hurt, but is less accurate.

    Note that you can fly the approach using GPS for bearing also, but you should display the raw VOR bearing also. See AIM 1-2-3.

    I'm guessing that #1 is the one that he wants to see

    Lastly, you're the PIC. Fly the approach the way you would fly it if nobody was watching. If you try to read the DPE's mind you're more likely to make a mistake. Just do it the way you were trained.
     
  17. EppyGA

    EppyGA Final Approach

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    If you're using Fred, I suspect he'll let you use the GPS to the fix and expect you to use the VOR down the approach. Don't forget to identify the VOR.
     
  18. obelix

    obelix Pre-Flight

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    Using Randy..
     
  19. MAKG1

    MAKG1 Touchdown! Greaser!

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    #2 is not kosher, but there is no reason you can't still monitor the approach on the GPS while using the CDI for the VOR. The "default" nav page on Garmins (at least 430 and 650) generally has its own CDI, and more importantly, identifies the distance to the next waypoint. You can also enter a direct-to on the GPS to the MAP to get a continuous distance to the MAP at all times (that can be useful for traffic calls on CTAF -- but the math isn't that hard).

    The reg says you must use the VOR (or LOC or whatever) between FAF and MAP as primary navigation. You can usually switch to VLOC early, but there are a handful of approaches where that isn't a good idea. VOR 19R at KCCR is an example. The VOR is the FAF, and there is also a turn there, so if you're on VLOC, you have to deal with the zone of confusion at the same time as a turn to final. While it can be done, I prefer to dial the final course in early and identify the station, then switch the CDI during the turn right at the FAF. On a more normal approach, I generally switch to VLOC as soon as I'm on the final approach course. Just hitting the CDI button and doing nothing else generally keeps the GPS approach going separately from the nav.

    Note there is a potential exception to the "early" rule as well. If the approach is an ILS with stepdowns along the final approach course (which seems common, at least around here), you may want to follow the stepdowns in order to intercept the GS at the "correct" place. That gives you an altimeter check. It's legal to intercept the GS early as long as you stay above the stepdown minimums at all times, but occasionally you can get a surprise. For instance, coupled ILS approaches at KLVK tend to false-intercept early, probably due to terrain reflections, and resulting in aggressive climbs at low power.
     
  20. James331

    James331 Touchdown! Greaser!

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    Holy cow, that's a lot of work, you wear out the buttons and knobs on your nav equipment much?

    Why not just fly, or let George fly, the GPS overlay while still having the VOR dialed up on another nav head to be legal, it's going to be less work, more accurate, much less likley hood to fat finger something, etc.

    On something more precise like a ILS that's one thing, fly it all RNAV till they put you on a intercept for the LOC, once the GPS turns you inbound, switch nav source and fly the ILS, if you go missed toga and switch nav sources back to GPS.


    Both methods I described above are kosher, and a lot easier and more precise.
     
    Last edited: Dec 19, 2016
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  21. whattauser

    whattauser Pre-Flight

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    I agree.
     
  22. MAKG1

    MAKG1 Touchdown! Greaser!

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    The stepdowns are additional work, but monitoring the approach on the GPS even while using the SAME CDI head (in VLOC) is how it behaves by default. You get to the default nav page by holding CLR for two seconds, no matter where you are. Not a lot of work there.

    Most of the aircraft I fly happen to have two GS receivers, but many rentals have only one, and it's in the GPS. At my previous club, NAV2 was often the less reliable radio. They swapped around nav/comms so that every airplane had the "good" one in COM1/NAV1. The second radio was often a crappy NARCO or somesuch.

    Having seen multiple instances of VOR radials differing from the corresponding GPS overlay (probably due to terrain or normal local interference), you may get into checkride trouble letting George fly the GPS. I've seen half-scale deviations in the GPS when the VLOC is centered (even in enroute mode, where the GPS scale is larger). That's not quite a bust, but it sure is getting close.
     
    Last edited: Dec 19, 2016
  23. Palmpilot

    Palmpilot Touchdown! Greaser!

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    Regarding your scenario #2, this is covered near the end of Chapter 1 of the AIM. An IFR GPS is an allowable substitute for ground-based navaids, except for course guidance on the final approach course. That must be done using the navaid named in the approach title.
     
    Last edited: Dec 19, 2016
  24. James331

    James331 Touchdown! Greaser!

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    You have it a little backwards on how I'd set it up, and that CDI screen is for the birds.

    I'd have that narco on the VOR, and the better nav head (and the one the autopilot/FD follows) on GPS.
     
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  25. MAKG1

    MAKG1 Touchdown! Greaser!

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    You do this on an ILS, too?

    The CDI screen is not really about the CDI. On 430s and 650s at least, it also has the ground speed, actual track, and next waypoint.
     
  26. flyingron

    flyingron Touchdown! Greaser!

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    Can't vouch for the other Garmins, but the 480 gets testy at you if you don't switch to the VLOC at the FAF. I'd switch (or allow it to switch), I still have the 480 and MFD graphical presentation for situational awareness.
     
  27. James331

    James331 Touchdown! Greaser!

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    To answer your first question, well I already did a couple posts up, but yes.

    I fly the ILS off the GPS right until I come onto the LOC, at which point I switch nav sources to the ILS, if I go missed, TOGA, nav source back to GPS. For VTF it's more or less the same, except I'll change from the GPS to ILS a little sooner.


    On your GNS, you should be able to get all the info you need for a approach on one of the two different map screens, just got to options for change fields and pick what you want to see.
     
  28. EppyGA

    EppyGA Final Approach

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    I've never used Randy. Don't you have to up to Anderson for him?
     
  29. Palmpilot

    Palmpilot Touchdown! Greaser!

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    It's legal because the approach doesn't have "DME" in the title, and there is no note saying "DME required." As has been pointed out, other means of identifying the MAP and the missed approach holding fix are provided on the chart.

    Note that if you have neither DME nor IFR GPS available, then you can't use the BUYAB fix minimums; you have to use the higher minimums (in the next box above).
     
  30. obelix

    obelix Pre-Flight

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    I used him for my PPL, very easy going guy. John sends everyone up there. Les took his test with him and said it was a good test. I guess I could use anyone..
     
  31. EppyGA

    EppyGA Final Approach

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    I do hear he is good. He was booked up when I wanted to schedule so I ended up going with Fred. My point was more about practicing the approaches where you'll take the ride.

    Good luck when you're ready!!
     
  32. obelix

    obelix Pre-Flight

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    I've got it scheduled for January. I'll probably go up the weekend before and shoot the approaches into greenwood and anderson, two of his favorites that I've heard about. It's only 40 minutes from LZU and I do have a few more hours I need to log between now and then anyhow. Want to go for a ride :) ...
     
  33. EppyGA

    EppyGA Final Approach

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    I'm down for that. When are you thinking?
     
  34. obelix

    obelix Pre-Flight

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    I'll ping you next week some time. I'm thinking the first week of January go up for some practice if you're around. Also off the entire week of christmas. Test is for the 10th. I'll shoot you sometime next week I can see a little better what the weather is going to look like. I'm thinking I need to shoot the VOR and ILS 5 a few times at anderson. It'll be good to get some opinions of another pilot who I haven't been training with.
     
  35. EppyGA

    EppyGA Final Approach

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    Sounds good