8
$\begingroup$

MEA, MORA, grid MORA, and MOCA for a non-mountainous area gives 1,000 ft clearance from the highest obstacle, and in mountainous area gives 2,000 ft clearance from the highest obstacle.

But what is the exact definition of a mountainous area?

I have also heard that MOCAs have a different clearance calculation for the mountainous area depending on the terrain/obstacle elevation, (3000 ft - 5000 ft gets 1500 ft clearance) and (above 5000 ft gets 2000 ft clearance) can someone clarify this.

$\endgroup$
0
7
$\begingroup$

(I'm assuming you're asking about the USA.)

14 CFR 91.177(a)(2)(i) says (emphasis mine):

In the case of operations over an area designated as a mountainous area in part 95 of this chapter, an altitude of 2,000 feet above the highest obstacle within a horizontal distance of 4 nautical miles from the course to be flown; or [...]

If you then go to 14 CFR 95, you'll see that it defines mountainous areas by latitude and longitude. It's entirely useless for practical purposes, but at least it's precise :-)

As for the MOCA, I can't find anything to support the different definitions that you mentioned. 95.1(e) simply says:

(e) The MOCA assures obstruction clearance on an ATS route, ATS route segment, or other direct route, and adequate reception of VOR navigation signals within 22 nautical miles of a VOR station used to define the route.

The AIM and PC/G support that; there's no other definition that I could find.

$\endgroup$
1
  • $\begingroup$ Thanks alot for that :D $\endgroup$ Jan 25 '19 at 8:42
0
$\begingroup$

Designated mountainous areas include those areas having a terrain elevation differential exceeding 3,000 feet within 10 nautical miles within those one arc-second quadrangles overlying terrain or U.S. territorial waters. This new definition would also align with that used by ICAO.

$\endgroup$
1
  • $\begingroup$ Do you have any sources you can add to back up your answer? $\endgroup$
    – dalearn
    Jan 18 at 2:09

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.