Where's the MAP on this, and why?

Discussion in 'Cleared for the Approach' started by Mistake Not..., Mar 19, 2017.

  1. Mistake Not...

    Mistake Not... Cleared for Takeoff

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    http://155.178.201.160/d-tpp/1703/05299R18.PDF

    KSYI, RNAV RWY 18.

    Where's the MAP for the LNAV approach?

    I understand the MAP for the LPV (follow glideslope down to DA). And for a localizer type of approach, I can identify the MAP when the heavy black line changes to the dotted "missed" symbology at a fix. But when the dotted missed symbology occurs -between- fixes... what then?

    I'm guessing it's either the VDP or the end of the runway. But I thought VDP were just just suggestions.

    Help?
     
  2. MauleSkinner

    MauleSkinner En-Route

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    The LNAV missed approach point is at the runway.

    Not being well-versed in NACO (or whatever they're called now) charts, I assume what's depicted is only the DA missed approach points.
     
  3. aterpster

    aterpster Pattern Altitude

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    How about you-get-what-you-pay-for charts?

    Having said the chart does show the runway threshold in the profile. Question as that asked by the OP can be answered by a thorough reading of the FAA chart legend and material on use of FAA charts.
     
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  4. Mistake Not...

    Mistake Not... Cleared for Takeoff

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    Well, I tried that.

    legend.jpg
    That's pretty clear. Except it doesn't coincide with a fix. Thus my confusion.

    But your response is useful. Only a designer of these charts could think these charts are clear. Would it kill you guys to put "MAP" on the fix designating the missed approach point?
     
  5. tsts4

    tsts4 Line Up and Wait

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    It's the flyover waypoint labeled "RW18" on the approach end of runway that's depicted on the plan view and called out in the profile view.
     
  6. Mistake Not...

    Mistake Not... Cleared for Takeoff

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    Sure, that's what I'd guess. But I can't find anything in the legend that would indicate that. If you had to -prove- it, what would you look at?
     
  7. MauleSkinner

    MauleSkinner En-Route

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    Since, technically, there are 3 different missed approach points on that chart, what do you suggest?
     
  8. Mistake Not...

    Mistake Not... Cleared for Takeoff

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    Good question.

    I'm assuming this is some sort of "everybody knows" convention. But if I had to do it, I'd extend the '*' note. Take the procedure I linked to. There's already a '*' for the VDP. Put an asterisk beside the RW18 fix, with MAP below it. then the note makes sense... "* LNAV only."

    Is that the convention? Since the LPV approach doesn't need the RW18 fix, I'm just supposed to assume it goes with (and defines) the MAP for the LNAV approach?
     
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  9. MauleSkinner

    MauleSkinner En-Route

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    The legend says the solid lines are terminal routes and the broken line is the missed approach.

    The plan view shows a solid line to the RW18 waypoint, with a broken line after that.
     
  10. Mistake Not...

    Mistake Not... Cleared for Takeoff

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    It does NOT show that. Look at the chart... if you're looking at the same chart I am, the solid line ends between the VDP fix and the RW18 fix.

    (Edit: Hang on a sec.. plan view... looking)
     
  11. MauleSkinner

    MauleSkinner En-Route

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    ....hanging on... :D
     
  12. Mistake Not...

    Mistake Not... Cleared for Takeoff

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    Interesting. (I'm referencing the same approach I posted.)

    There appears to be a 'fly over' way point at the north end of the runway. Which is nice. OTOH, the dashed symbol doesn't begin until the south end of the runway. So according to the plan view the map is at the other end of the runway. ;/
     
  13. tsts4

    tsts4 Line Up and Wait

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    MAPs are described in the FAA Instrument Procedures Handbook, GPS non- precision approaches use a flyover waypoint to determine the missed approach point--simple as that.

    The dashed line is associated with the LVP approach to indicate executing the missed at the DA. For an LNAV you would motor at the MDA to the RW18 waypoint disregarding the dashed line prior to the waypoint
     
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  14. MauleSkinner

    MauleSkinner En-Route

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    Technically it's a solid arrow rather than a line...you can see the arrowhead at the RW18 waypoint. :)
     
  15. Mistake Not...

    Mistake Not... Cleared for Takeoff

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  16. Mistake Not...

    Mistake Not... Cleared for Takeoff

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    lol. Noted.

    So. If you were going to tell someone how to find the MAP for an LNAV approach, it's:
    * A Fly OVER waypoint
    * ...on the final approach course
    * ...located on or after the LPV MAP depicted in the profile view
    * ...usually designated as "RW" and the runway name
    ?
     
  17. Palmpilot

    Palmpilot Touchdown! Greaser! PoA Supporter

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  18. Bill Watson

    Bill Watson Pattern Altitude

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    The solid line starting at the RWnn and MAP is the runway. Since the first segment of the miss procedure is to climb straight ahead, the dashed line overlays the solid runway depiction. It becomes dashes become visible once past the runway symbology.

    It makes more sense, or perhaps less, looking at an approach to a parallel runway with a straight miss segment (example above)

    OTOH, if the first segment is an immediate turn, the dash line is visible (not overlaid) starting at the MAP. Try KMGW RNAV Y Rwy 18 for example.

    Graphically, it seems logical.




    Sent from my iPad using Tapatalk
     
  19. tsts4

    tsts4 Line Up and Wait

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    Yes but I wouldn't ref the non-precision missed approach point to the LPV in any way as there is no relationship, just as there's no relationship between an ILS's DA and the LOC only missed approach point. And don't forget that the flyover waypoint is depicted on the plan view as a 4-point star within a circle as opposed to the fly-by waypoints which are just the 4-point star with no surrounding circle.
     
  20. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    The point where the dotted arrow departs from the glide path, while stated to be the MAP, rarely is. They always show it departing from about the intersection with the MDA, even when other information on the chart clearly shows the MAP is further along (typically the runway).

    On an RNAV(GPS) approach, the MAP is where the MAP waypoint is in the procedure. My GPS very nicely says "missed approach" when I get there.
     
  21. aterpster

    aterpster Pattern Altitude

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    ,
    I am not one of "those guys." I use Jeppesen charts. Having said that, the profile view you posted is for an FAA chart ILS, not RNAV.

    Jeppesen profile view:

    Jepp Profile.jpg
     
  22. aterpster

    aterpster Pattern Altitude

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    Mistake Not... likes this.
  23. jordane93

    jordane93 Final Approach PoA Supporter

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    Another reason why Jepp is superior to government plates.
     
  24. aterpster

    aterpster Pattern Altitude

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    Yes, plus the coverage doesn't end at the U.S. border. Another point: The FAA charts are bound by a rigorous set of charting specification down to font type and size, etc, and these specs cannot be changed without jumping through a lot of hoops (in other words, government inaction). Attached is the regulatory source document for the OP's example; all the data are there.
    KSYI Shelbyville TN RNAV 18 Source.jpg
     
  25. aterpster

    aterpster Pattern Altitude

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    Interestingly, the U.S. is the only country that publishes charts on textual forms rather than in graphical format. Further, the U.S. is the only country that issues approach procedures as individual amendments to Part 97. (Airways are Part 95). In other countries, the IAP becomes regulatory as an air traffic clearance when issued by ATC. Sort of like SIDS and STARS in this country (and elsewhere). The FAA has its own drum core. :)
     
  26. WillFly4Food

    WillFly4Food Filing Flight Plan

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    Actually, that is the missed approach point. It resembles a fly over point, but not exactly - the MAP symbol is quite a bit smaller than a fly over way point symbol. The size of "fly over" and "fly by" waypoints are similar, so if you're looking for a symbol to compare a MAP symbol to and don't see any fly overs, you can just compare symbol size to a fly by symbol.

    The heavy solid line terminates here in order to make way for the runway symbol, also a solid line. But this is not an RNAV approach, so don't look for an RNAV MAP symbol. This is an ILS or LOC approach. On this one, if flying the LOC, the MAP is at the SJC VOR/DME station, or DME=0, which appears to be at least part of the reason for the DME required comment. I would think you could also watch for SJC station passage. But for that would want to have a secondary Nav indicator tuned to that station.
     
  27. Mistake Not...

    Mistake Not... Cleared for Takeoff

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    Very interesting. Thanks, aterpster!
     
  28. aterpster

    aterpster Pattern Altitude

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    The LOC (GS out) MAP is the ILS DME (ISJC) 1.4 DME.
     
  29. MAKG1

    MAKG1 Touchdown! Greaser!

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    Which is DAMN close to the 30L threshold, which of course is invisible during a missed approach. The VORTAC is located just past the DER.
     
  30. aterpster

    aterpster Pattern Altitude

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    What difference does it make if you can't see the threshold for a missed approach? In any case, you can't "roll your own" MAPs.
     
  31. MAKG1

    MAKG1 Touchdown! Greaser!

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    You can't specify the MAP is the end of the runway if people may not be able to see it. You have to specify it some other way. Like DME.
     
  32. Palmpilot

    Palmpilot Touchdown! Greaser! PoA Supporter

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    Any idea what the reason could have been for equipping the ILS with its own DME, instead of using the one on the San Jose VOR?

    I'm guessing that on NACO charts, the last vertical line on the profile view indicates where the MAP is. That seems to agree with the explicit marking on the Jepp charts you posted.
     
  33. WillFly4Food

    WillFly4Food Filing Flight Plan

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    Yep, I blew it. (Don't do approaches on the fly after just waking up. For some reason I had started to think of it like a VOR approach.)

    By the way, remember that the MAP in no way indicates a position you can safely execute a landing from. It's just a point in space marking the beginning of the Missed segment of the approach, that you have to be able to identify with the equipment you have on board.
     
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  34. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    Yep, that's what the VDP is all about.
     
  35. MAKG1

    MAKG1 Touchdown! Greaser!

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    You bet. It's where missed approach turns are measured from, nothing more. It's kinda obvious a straight-in landing from 250 feet or more above the threshold cannot be done, unless the runway is very long.
     
  36. aterpster

    aterpster Pattern Altitude

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    That's they way it has always been. That's why they're called non-precision approaches. Having said that, so long as I am not flying for hire, I do not have to land in the official TDZ. On some very long runways I could cross the threshold at MDA and safely land in, say, a Cessna 182. KRIV is an example.
     
  37. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    Yep, usually by the time they put an instrument approach (let alone an ILS), in you're talking about a runway long enough that I can go from the MDA at the threshold and land the plane with "normal" manouvers.
     
  38. MAKG1

    MAKG1 Touchdown! Greaser!

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    No. There are quite a number of instrument approaches at not-very-long runways. You will never make it at KPAO GPS 31, for instance. That's a 460 foot straight-in minimum with the MAP at the threshold, and a 2400 foot runway. Or KRHV RNAV Y 31R (that one has a 1200 AGL minimum on a 2700 foot runway -- yikes!). Or O69 RNAV 29 (620 feet over a 3600 foot runway, for LNAV minimums).

    You don't have to operate out of IAD to find instrument approaches anymore. They are at quite a lot of smaller airports.
     
  39. midlifeflyer

    midlifeflyer Final Approach

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    It's so funny. There seem to be two "approaches" to the chart in this thread:

    1. Learn how to read it.
    2. whine about it not being the way you would write it.
     
  40. aterpster

    aterpster Pattern Altitude

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    That doesn't even make sense.