LP approach question

Discussion in 'Cleared for the Approach' started by benyflyguy, Jun 10, 2018.

  1. benyflyguy

    benyflyguy Pre-takeoff checklist

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    During training I got my first crack at an LP approach last week in to RNAV08 at KDXR. I have a 430 with WAAS. As expected I didn’t get any vertical guidance.
    So today I and flying an approach into KSEG on the RNAV 35, it too also has an LP approach. But this time a glide slope popped up?!? I didn’t expect it and was not sure what to think about it.
    I was under impression that I should not get any vertical guidance on a LP approach. While I appreciated it I wasn’t sure I would be able to trust it.
    Thoughts?
     
  2. gsengle

    gsengle Pattern Altitude

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  3. benyflyguy

    benyflyguy Pre-takeoff checklist

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    That’s helpful. Thanks! I wonder why that is not delineated on the approach plate. I realize it is equipment sensitive. I was prepped for “dive and drive” but was happy. Now that I read that I remember the 430 showing something to the effect of a +v on the left lower corner perhaps.
     
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  4. benyflyguy

    benyflyguy Pre-takeoff checklist

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    So I just looked at the plate again. The plot thickens. So if I’m getting vertical guidance the minimum is 600’ higher! As it appears if I’m getting vertical guidance then I have to use the LNAV minimums. I was planning on flying to the LP miminums. I need to go back to the gps and see if I can choose between the LP vs the LNAV. In this case I would prefer the LP as the miminums are much lower.
    So if the 430 WAAS gives me vertical guidance on a LP approach my minimums might go up?? That doesn’t make a lot of sense.
     

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  5. gsengle

    gsengle Pattern Altitude

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    Yep be careful an advisory glideslope has gotchas like stepdown fixes etc


    Sent from my iPhone using Tapatalk
     
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  6. Clip4

    Clip4 Pattern Altitude

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    Your charts are NACO. Your data subscription is Jeppesen. LNAV+V is a Jeppesen product to provide some guidance to the MDA.
     
  7. azure

    azure Final Approach

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    Pretty sure I read somewhere that just like LNAV+V, WAAS GPSs can add an advisory glideslope to a LP approach to make it LP+V - I think this is a Jepp innovation so it would also depend on the database. Your GPS should have a field that displays the approach type, and should say LP+V if that's what is going on.

    I have never flown a LP approach with my 480, but I have flown LNAV-only approaches with advisory glideslopes, and it does annunciate LNAV+V for those.
     
  8. aterpster

    aterpster Pattern Altitude

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    That is not correct. With a WAAS box where there are LP and LNAV minimums, so long as WAAS is functioning the avionics default to LP. And, the hint that you should get LP+V is indicated in the profile view. This must be confirm by seeing LP+V when you review or select the approach in your 430.
     

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  9. aterpster

    aterpster Pattern Altitude

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    Jeppesen won't include an advisory GS in the database if it doesn't clear stepdown fixes. The greater concern is using the advisory GS from MDA to the threshold.
     
  10. benyflyguy

    benyflyguy Pre-takeoff checklist

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    Thanks for the help. Will look for the confirmation next time I fly that approach. An in future look for that with all LP approaches. The king 430 course doesn’t review that I think.
    I would never use glide slope to threshold. That’s below miminums!!! If I don’t see at mda and at map then it’s go to the missed!
     
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  11. MauleSkinner

    MauleSkinner En-Route

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    I don't think Wally's talking about using the glide path to bust minimums...but once you break out, there could be obstructions that penetrate that glide path as you descend visually from MDA to the runway.
     
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  12. AggieMike88

    AggieMike88 Touchdown! Greaser!

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    As I am on the final approach course for an RNAV approach, one of my checklist callouts is the annunciation my WAAS GPS is showing me. This way I verify what I was expecting (and briefed) or recognize I got something else and I need to update the minima I'm using to the guidance I'm being provided.
     
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  13. luvflyin

    luvflyin En-Route

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    What did the flight mode annunciation say?
     
  14. labbadabba

    labbadabba Pattern Altitude

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    Yep ESPECIALLY at a place like KDXR. That +V is advisory only on an LNAV approach. You still have to be above your step down mins.
     
  15. benyflyguy

    benyflyguy Pre-takeoff checklist

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    At KDXR was the first time I encountered a LP approach. So I wasn’t expecting glideslope and didn’t get one at all which makes sense. In fact the terrain is a good example of when a glideslope could get you in trouble.
    Then less then a week later I do another LP and expected no glideslope. Thinking back I remember the the Left Lower corner area did have LP+V. I will have to shoot the approach and pay attention. Will make it part of my routine checklist to announce it as well when setting up my approach
     
  16. labbadabba

    labbadabba Pattern Altitude

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    Yep, a LPV is protected precision guidance (like an ILS) but a LNAV+V is suggested vertical guidance and is not published; these are the ones that a really helpful but also can get you into trouble. The newer GPS boxes will even give you a 3-degree advisory glidepath for visual approaches but again, maintaining your situational awareness is incumbent upon you as PIC.

    I know before my checkride, I wrote out the different types of GPS approaches and what they mean. Here's a solid article on it:

    http://www.boldmethod.com/learn-to-...ference-between-lpv-and-lnav-vnav-approaches/
     
  17. azure

    azure Final Approach

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    Just to be clear, it looks like @benyflyguy wrote LP+V not LPV. Two different things. LPV is for all intents and purposes a precision approach as you said, LP+V is LP with an advisory glideslope.
     
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  18. luvflyin

    luvflyin En-Route

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    Good idea. The flight mode annunciation is pretty important.
     
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  19. denverpilot

    denverpilot Taxi to Parking

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    Extremely. The joke on the GNS gear is that the most common way to bust a checkride is not to flip it to “VLOC” (so called “green needles”) when established on an ILS.

    On the GTN ... *if* the unit is set to automatically capture and cycle it’ll flip it for you, but you’d better a) check the setting in the menu before takeoff and b) monitor it anyway and be ready to flip it yourself if it doesn’t switch.
     
  20. SbestCFII

    SbestCFII Line Up and Wait

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    On the 430W, if you're getting a "glideslope" the your unit will annunciate LP+V. The "glideslope" will take you down a slope at or above the published "step-down" altitudes. However +V also means that the piloy is still responsible for ensuring that safe altitudes during descent on the "Glideslope."
     
  21. AggieMike88

    AggieMike88 Touchdown! Greaser!

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    That's why "CDI FLIP" is on my approach checklist.
     
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  22. luvflyin

    luvflyin En-Route

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    Yup. It’s been called the $400 button. That’s what it’s gonna cost you for another checkride
     
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  23. Ravioli

    Ravioli En-Route

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    From the 430 manual, page 6-26.

    "The GNS 430 can be set to automatically switch the external CDI output from GPS to VLOC as the pilot intercepts the final approach course. When the ILS
    approach is activated, the GNS 430 automatically switches within 1.2 nm left or right of the final approach course. This switch can take place anywhere from 2.0 to 15.0 nm from the FAF."

    Please send your $400 to @Ted DuPuis to support Cloud Nine.
     
  24. Ted DuPuis

    Ted DuPuis Administrator Management Council Member

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    That would be much appreciated. Just dropped the MU-2 off for its first 100/200 hour (annual) inspection. :eek:
     
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  25. benyflyguy

    benyflyguy Pre-takeoff checklist

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    Thanks. Very helpful. Will plan on going into menu and updating this. I can’t think of a reason not to have this do it automatically??!!
     
  26. Ted DuPuis

    Ted DuPuis Administrator Management Council Member

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    Extra note for those interested: We have a crowdfunding effort going on for the inspection here:

    https://poundwishes.com/donate/2869826/mitsubishi
     
  27. benyflyguy

    benyflyguy Pre-takeoff checklist

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    My buddy has an mu2. Sweet ride. But those bills I think are only ever in the 5 fig range:eek::eek::eek:
     
  28. Ted DuPuis

    Ted DuPuis Administrator Management Council Member

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    It depends on the shop and the squawks on the plane, as with anything. The shop we are using is giving us a generous discount on the base inspection as well as labor, but we're also going in with a few known items to look at.
     
  29. chemgeek

    chemgeek Pre-takeoff checklist

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    Be very careful. Only the LPV or LNAV/VNAV approach provides vertical guidance inside the FAF that guarantees separation from terrain. The former has more precision. LP approaches are the GPS analog of localizer approaches, with precision lateral guidance, but no vertical guidance. Some LNAV approaches, e.g. LNAV+V in your GNS430, will provide advisory vertical guidance, but this does NOT necessarily provide for separation from terrain and may take you below stepdown fixes. Following that advisory vertical guidance when IMC could at some airports put you close to terrain. I'd be happy if Garmin disabled the +V in these approaches.
     
  30. bkspero

    bkspero Pre-takeoff checklist

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    Be mindful that the switch happens at between 2 and 15 nm from the FAF. I recall reading a post a few years ago by a pilot who on vectors to final intercepted the approach course inside of 2 miles from the FAF. The CDI didn't switch automatically. He caught it and switched it manually. Moral being that if you change to automatic switching, make sure you continue with a manual check.
     
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  31. benyflyguy

    benyflyguy Pre-takeoff checklist

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    After thinking and reviewing. I think I’m going to plan on making part of my “establishing on the approach” checklist. I have a habit of checking the approach chart MDA three separate times in short period of time. Checking the gps for type of approach/vloc can be something I do in between the altitude check. Why three? My CFII got me into that habit. You can look at something once and mix it up, even twice, but thrice, there’s little chance for a mistake three times in a row.
     
  32. denverpilot

    denverpilot Taxi to Parking

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    You have to. Automation must be managed. It lowers workload but it also goes wrong.

    If you’re inside the FAF and haven’t confirmed “the boxes” are set, sooner or later you’re toast. Checklists are great, but it also just has to become an internalized habit. The checklists help with that at first and confirm it later after it’s ingrained.