A few departure clarifications

E

Electric

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Electric
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!
 
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
 
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This calculation also includes the assumption that you will cross the departure end of the runway at at least 35 ft. The W, X, Y surfaces determine the resulting climb gradient. But technically, yes. The fence is considered in the W, X, and Y surface intrusion calculation. All permanent objects are considered.

So the climb gradient will start at the runway end at 35 ft then 200 fnm or 243 fnm or whatever to give the proper increase per nm based on the resulting unbroken surface. Any intrusion into those surfaces will result in a steeper cg and may trigger a controller procedure to clear the area if the offender is a vehicle and to inform the pilot of the intrusion if a vehicle.

tex
 
Dave S. said:
This calculation also includes the assumption that you will cross the departure end of the runway at at least 35 ft. The W, X, Y surfaces determine the resulting climb gradient. But technically, yes. The fence is considered in the W, X, and Y surface intrusion calculation. All permanent objects are considered.

tex
Click to expand...

There is no W, X, or Y surface on a departure procedure. Those are for approach procedures (ILS, LPV) only.
 
You're right. We have it on all ends of our runways and I lost my mind for a minute.

I was thinking of the ROC surface.

Tex
 
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