A few departure clarifications

Discussion in 'Cleared for the Approach' started by Electric, Mar 20, 2017 at 10:23 PM.

  1. Electric

    Electric Pre-Flight

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    Have a few questions that I can't seem to find the answers anywhere:

    1. If I depart straight out from a runway with standard T/O minimums, am I protected against the "low close in obstacles"? Do departure minimums and ODPs protect me from the low close in obstacles?

    2. How far out does Obstacle Clearance Surface (OCS) end? I've heard several answers. One being 25nm normally and 46 in mountainous areas. The other answer I've heard is that you supposed to be on a positive course guidance within 10NM departing straight out, and within 5NM after turning. And I've also read that that the OCS is unlimited.

    Thanks in advance!
     
  2. luvflyin

    luvflyin Pattern Altitude

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  3. RussR

    RussR Line Up and Wait

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    1. Not really. They are "low close-in" obstacles because you are expected to be able to avoid them visually or otherwise easily. They are the small stuff, like the fence that's a couple hundred feet away, that would cause a climb gradient of greater than 200 feet per NM but only to a very low altitude (less than 200' AGL). Further, these calculations are based around the airplane getting airborne on the very last foot of the runway. So they are not a factor for the vast majority of airplanes. But they are noted because they do technically penetrate the OCS, and some companies do use them in calculations for climb - one engine inoperative, that kind of stuff.

    2. The OCS ends at 25/46 nm if it is what's known as a "diverse" departure - meaning no "route". If there is a departure route established, then the OCS extends along the entire length of the route, until the obstacle clearance reaches the appropriate enroute value of 1000 or 2000 feet. The requirement for PCG is really a separate issue than the OCS (the PCG is a "horizontal" issue, while the OCS is a "vertical" issue).

    Reference if you really want to get into it - FAAO 8260.3C, chapter 14.

    https://www.faa.gov/regulations_pol...fm/go/document.information/documentID/1029266
     
    Last edited: Mar 21, 2017 at 11:26 AM
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  4. Electric

    Electric Pre-Flight

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    Thanks, good information!