Interesting approach #1: RNAV Y 16R at EUG

Discussion in 'Cleared for the Approach' started by coma24, Nov 12, 2019.

  1. coma24

    coma24 Line Up and Wait

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    Came across this one while searching for crappy r/w WX in the sim. RVR was 1800 and so were the minimums, so it was perfect.

    Launch from KCVO on the CVO4 SID, straight into the ILS 16R, missed, vectors for the RNAV Y 16R. I pull up the RNAV plate and start briefing the notes. I see two new things I'd never seen before...figured I'd share:

    Thing #1: LNAV minima N/A is simultaneous approaches are in use (thx rwy 16L!). I check the ATIS (was flying in a simulated ATC environment which included a very realistic ATIS) and sure enough, simultaneous approaches are in use. So, thank goodness for WAAS.

    Thing #2: "Use of FD or AP providing RNAV track guidance required during simultaneous operations."

    Holy cow, THAT is new to me. I know it's a thing for RNP approaches,which I've dabbled with for fun in the sim, but to see this on a RNAV (GPS), that was eye-opening. It does make sense with simultaneous approaches, I just hadn't seen it before.

    Are these common at airports with parallel rwys or is EUG just kinda special?

    As much as I'm excited to have WAAS in my airplane at last, I don't have a FD and would've been forced to rely on the AP to fly the lateral portion of the approach, which I don't trust as far as I could throw it.

    Followup question...why is the same #2requirement NOT included on the ILS?
     
  2. coma24

    coma24 Line Up and Wait

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    I debated posting this followup as it wasn't my original intention, but I found the sim session so useful, I figured I'd share.

    Here's a video of the sim session (the link is good for about 2 weeks and will eventually expire unless I export it as a highlight): https://www.twitch.tv/videos/505135574?t=01h30m09s. That is queued up at 600ft on the ILS into EUG.

    The sequence is:
    - missed approach on the ILS
    - tower hands to Cascade approach, request vectors for RNAV 16R, "Yankee?" "affirm." "vectors or from Corvallis?" "vectors"
    - reminder about loading vectors vs IAF ensues
    - vectors to final for approach
    - go missed for realz again
    - full missed, holding
    - rqst the ILS RWY 17 at KCVO
    - fly full approach to mins, JUST make it down, cancel IFR and end the session

    Some context:
    - X-Plane 11, streamed live on twitch (that's what the chat messages are all about)
    - stock Baron. I'm ASEL real world, but jeez, a twin is really just like a single, until it BECOMES a single, THEN you have to know how to fly twin...
    - yes, the ATC is a real person. There are online services which provide this to varying degrees, this one is PilotEdge. This is who I'm getting vectors from, requesting the next approach, etc.
    - our callsign is N132KT (a DA-20 I flew during PPL training), despite the placard saying N45XS.

    For those who haven't seen what modern day sims can do, maybe this will provide a nice update. The shadows on the panel are not just eye candy (once we're on top), they're very useful as they provide hints as to whether you're turning or not. If you think you're flying straight and the shadows are moseying left to right or right to left, it's time to check that scan.
     
  3. Arnold

    Arnold Pre-takeoff checklist

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    My guess is the runways are closer than the normal min. for parallel approaches. Also their thresholds are roughly the same distance from the airport boundary. Thus jumping through hoops to assure separation.
     
  4. jordane93

    jordane93 Final Approach

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    LNAV NA during simultaneous approaches in use is common. Not sure about your second question
     
  5. luvflyin

    luvflyin Final Approach

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    looks like they are exactly 4300’ which is a minimum for some simultaneous approaches. I’d bet they built the second runway with exactly that in mind. There are lesser minimums nowadays in some circumstances with some of the newer high update Radars. My guess is the requirement for FD or AP may have something to do with enough experiences of pilots not making good turns to final that they decided to make that requirement. Maybe the LP(localizer performance) is just not quite as accurate as Localizer. Just like WAAS Glideslopes are just a little less accurate than ILS Glideslopes. Just my guesses.
     
  6. AA5Bman

    AA5Bman Pre-takeoff checklist

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    Wow. It’s been a long time since I’ve seen a sim - that’s amazing. I remember flying cubes in in the 90s...
     
  7. coma24

    coma24 Line Up and Wait

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    Glad you enjoyed, and yes, sims really are amazing...I wish more pilots were aware. The litmus test is whether your thought process in the sim is the same as the real airplane and whether you feel like you're really drawing on the same skillset that you use in the airplane. I can put my hand over my heart after doing this for a number of years...it's at the point where, turbulence aside, flying approaches in the sim is effectively the same as doing it in my airplane in terms of proficiency.

    That is not a fancy sim setup, either...I'm using a $66 joystick (Thrustmaster T-16000M which is a real sleeper, it's stupidly precise and has no 'play' in it, $150 rudder pedals and a gaming-grade PC). The plane is the default Baron that comes with the sim (although I did tune the coefficient of drag of the fuselage to get the cruise speed closer to r/w numbers, it was a bit of a slouch otherwise) :)
     
  8. Clip4

    Clip4 Final Approach

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    Nothing special about that approach.
     
  9. coma24

    coma24 Line Up and Wait

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    It looks like you're right. I just checked a couple of other airports with parallel runways (LAX and SEA) and this is definitely a thing. Clearly not unique to EUG, I just hadn't looked closely at RNAV's at airports with widely-spaced parallels before.
     
    Last edited: Nov 13, 2019
  10. Clip4

    Clip4 Final Approach

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    Approaches are designed using set standards so they follow a rather predictable pattern.
     
  11. schmookeeg

    schmookeeg Cleared for Takeoff

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    Ayup.
     
  12. coma24

    coma24 Line Up and Wait

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    Am aware. My exposure to RNAV approaches at airports with appropriately-spaced parallels is low, I think that's why I just came across these recently.

    I'm still seeking to understand why the FD/AP requirement exists for the RNAV approach, but not the ILS. I don't see how the accuracy of navigation source is an immediate factor, unless the thinking is that RNAV is marginally less accurate (laterally) than the ILS. Compound that with pilot error in adhering to the course and the sum of errors may be a concern. That's all I've got, though.
     
  13. N1120A

    N1120A Line Up and Wait

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    The RNAV (GPS) 25 into KHHR also has the same AP or FD limitation during simultaneous operations with KLAX. It can also, based on the chart, only be carried out when LPV is available during simultaneous operations, yet a NOTAM says you only get the LNAV mins.
     
  14. luvflyin

    luvflyin Final Approach

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    Yup. The chart says ya gotta have Localizer Performance. The Notam says you can't do it with LP. So it just can't be used simultaneously with LAX Approaches. I wonder how many 'incidents' they had before someone said "we gotta quit doing this." Another thing that could have happened is Separation Criteria changed for Simultaneous Approaches and this situation didn't meet them. My guess is they had some close ones.
     
  15. N1120A

    N1120A Line Up and Wait

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    That's not exactly what it says. It says the DA for LPV and LNAV/VNAV is NA, so you can only go to the LNAV mins, but you need LPV available to actually do the approach with simultaneous operations. So they want you to do the approach with WAAS only, but only to the (only 9 feet higher) same mins as the LOC. The silly thing is that the GPS approach is safer and more accurate than the LOC, and even provides vertical guidance.

    The reality is that they want you on a visual with guidance into HHR, if at all possible.
     
  16. luvflyin

    luvflyin Final Approach

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    Gotcha. Kinda. Something is still not passing the logic check with me though. The Visibility Minimum. So 'mins' would be the LNAV MDA and the LPV(1 1/2) or LNAV/VNAV(1 7/8) Visibilty. By that logic you could still do it without LP if you had 1 7/8.
     
  17. N1120A

    N1120A Line Up and Wait

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    Except that the chart says LNAV is NA when doing simultaneous operations with LAX, which is always and forever. You have to have LPV.
     
  18. luvflyin

    luvflyin Final Approach

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    Ok. The LPV has minimums, like all Approaches. It is 571-1 1/2. But DA, 571, is NA. So I guess we make up a ‘hybrid’ minimum for the Approach. Keep the published Visibility minimum and pick an Altitude minimum from another line of minimums.
     
  19. N1120A

    N1120A Line Up and Wait

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    Basically, they say to treat it as a non precision approach.
     
  20. aterpster

    aterpster Pattern Altitude

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    You can descend on the LPV GS but to the LNAV MDA. My guess this is all about SCT wanting the MAP to be the runway threshold.
     
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  21. N1120A

    N1120A Line Up and Wait

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    Yup, and to not allow precision minimums on an approach so close to LAX. No reason for that approach to not be lower otherwise. Notice they even keep that 1500' segment from HASHY to ZANIR?
     
  22. aterpster

    aterpster Pattern Altitude

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    The DA is constrained by a transmission tower and the missed approach surface.
    CA_KHHR_RNAV GPS RWY 25_A1_F_CORRECTED_Page_07.jpg