Welcome Guest. Sign in or Signup

1 Answers

Why MAP and the starting point of the segmented line do not coincide?

Asked by: 1841 views General Aviation

Have a look at this chart: http://155.178.201.160/d-tpp/1701/09491R16.PDF (KEKS RNAV(GPS) RWY 16)

In the profile view of this chart, why the MAP (RW16) and the starting point of the segmented line signifying the missed approach course do not coincide? Not just in this chart. As I see it, it looks like there are a greater number of charts with this disagreement than those with coinciding the MAP and the starting point of the segmented line. How am I supposed to interpret this?

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

1 Answers

  1. Best Answer


    Russ Roslewski on Jan 20, 2017

    Understand that what you are looking at on this approach (like many, many others) is actually 4 approaches combined into one chart. They are all identical up to the final approach fix, but the DA/MDA is different for each of the four. Then once passing the MAP, the missed is back to being the same for all of them.

    Each line of minimums is really a separate approach:
    LPV
    LNAV/VNAV
    LNAV
    Circling

    What is the MAP on a vertically guided approach? It is defined as the point where you reach DA on the design glidepath. This will happen at some point before the runway, and on this approach will happen at different distances from the runway depending on if you are flying the LPV or LNAV/VNAV line of minima. So the notional depiction of where the dashed “missed approach” line starts is basically correct for these two lines.

    For the LNAV and Circling lines, the MAP is at the runway threshold, RW16. So the dashed line is NOT correctly depicted for these non-vertically guided lines.

    So, basically they chose to depict one and leave the other one off, presumably based on chart clutter. The charting standard says to depict the dashed line based on the “best” level of minimums, in this case the vertically-guided LPV line.

    If it instead depicted the line leveling off and going to the LNAV/Circling MAP (RW16), then you could just as readily ask the reverse question – “why does the solid line level off and go all the way to the runway, when I know I’ll be going missed before that, when I reach DA?”

    In reality, once flying, it doesn’t matter which is depicted, since you won’t be looking at the chart at that point anyway. You fly to the MAP (either DA or the fix) as appropriate, and go missed from there.

    +2 Votes Thumb up 2 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.