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Hello,

As you can see, at the missed approach point, the chart gives 984 feet. On the other hand, The Decision altitude given as 959 feet. What is the reason ? Thanks.

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The glideslope altitude at the LOC MAP is 984. That’s not the DA.

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    $\begingroup$ Isn't the LOC MDA 1750? What's the point of including this extra figure? $\endgroup$
    – Ben
    Commented May 22, 2023 at 22:08
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    $\begingroup$ @Ben The MDA is 1750, but if you were flying the ILS (and could execute the 5.4% climb out) then the altitude serves as a check just prior to hitting the DA (959). Likewise, if you were leveling at 1750 on the LOC it would provide a good indication for how much lower the normal 3 degree glidepath is to the runway at the MAP (should you get the runway in sight). $\endgroup$
    – Timbo
    Commented May 22, 2023 at 23:20
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    $\begingroup$ If you look at the history in the U.S. of "middle marker beacons" - MM (FAA Instrument Flying Handbook, AIM, etc.) you would see that their primary purpose was to alert the pilot, flying an ILS, that he/she was at the approximate decision height point (of course now the point would be the Decision Altitude). When I received my Instrument Rating in 1973 I can't remember ever flying an ILS without an MM. They were used as a cross check that you were near or over the DA/MAP. My guess is that since the LOC MAP is already marked (.7 from IYEN), this is serving the same purpose as MM used to. $\endgroup$
    – user22445
    Commented May 23, 2023 at 0:20

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