Mea Gap?

[MikeSF340]

What is an "MEA GAP?" I know I have heard the term, but I have no idea what it is. Any help would be appreciated.

Thanks!

 

[Andy Neill]

http://www.flightsimaviation.com/aviation_theory_17_Enroute_Charts.html

At this website, you will read that an MEA gap exists when you cannot receive the necessary navaids for the airway at the MEA. In other words, although the MEA will guarantee you terrain and obstacle clearance, it will not guarantee navigation capability.

 

[minitour]

...wouldn't that make it a MOCA?

-mini

 

[Andy Neill]

No, a MOCA guarantees you terrain and NAVAID but only within 22 miles of the faicility.

....or to say it better, a MOCA may be involved when there is an MEA gap, but an MEA gap is NOT a MOCA.

 

[minitour]

No, a MOCA guarantees you terrain and NAVAID but only within 22 miles of the faicility.

....or to say it better, a MOCA may be involved when there is an MEA gap, but an MEA gap is NOT a MOCA.

Okay...I think you said what I was thinking in your second sentence...

like...if I'm 36 nm away from a NAVAID then the MEA gap would be the/a MOCA...but if I'm 21 nm away from a NAVAID the MEA gap would be just an MEA gap....

...I guess I never considered an MEA gap close to a navaid....thanks for clearin that up!

-mini

 

[Andy Neill]

like...if I'm 36 nm away from a NAVAID then the MEA gap would be the/a MOCA...but if I'm 21 nm away from a NAVAID the MEA gap would be just an MEA gap....

-mini

I wouldn't say that.

 

[SSDD]

MEA gap usually involves a leg with navaids that are hundreds of miles apart. Somewhere in the middle you would be beyond the operational service volume of both navaids. There are a few examples out west. J56 between FFU and MVA is 312 miles and the MEA is a woping 33,000'. Also J158 from LCU and MVA is 256 miles and the MEA is 23,000'. On J36 GTF and DIK are 354 miles apart.

MOCA and MEA gaps are two different issues. Mini seems to be confused. At 36 miles from the navaid, MOCA would not apply. At 21 miles you wouln't have an MEA gap, they'd just raise the MEA.

 

[minitour]

...MOCA and MEA gaps are two different issues. Mini seems to be confused. At 36 miles from the navaid, MOCA would not apply. At 21 miles you wouln't have an MEA gap, they'd just raise the MEA.

I understand the two different issues thing...

...but why wouldn't the MOCA apply at 36 miles?

It provides obstruction clearance and NAVAID reception to 22nm...now what if you're using GPS? You don't need NAVAID reception...just RAIM.

You still get "guaranteed" obstruction clearance.

During my oral, the examiner pulled out a chart and we talked about exactly that scenario (which is why I brought it up)...don't know which chart but it was a low enroute...anyone know?

Andy:
How would you say it?

-mini

 

[IP076]

Yeah, that whole GPS thing is confusing...Technically speaking, to use GPS as a sole source of navigation, you need to have a back up.

So, do you legally have a back up at the MOCA?

Just throwing it out, I used to say the same thing you are, now I'm just hearing lots of people saying that you can't legally do it.

I'll be honest in saying that I havent had the time lately to peruse the appropriate faa docs and find out, if anyone has an hard info one way or the other, I'm all ears.

 

[minitour]

Yeah, that whole GPS thing is confusing...Technically speaking, to use GPS as a sole source of navigation, you need to have a back up.

So, do you legally have a back up at the MOCA?

Just throwing it out, I used to say the same thing you are, now I'm just hearing lots of people saying that you can't legally do it.

I'll be honest in saying that I havent had the time lately to peruse the appropriate faa docs and find out, if anyone has an hard info one way or the other, I'm all ears.

That was the "argument" I made but the examiner quickly assured me that if I was flying along at the MOCA and lost RAIM or my GPS went out completely, I could just fly up to MEA and boom...be legal.

Then I asked about high density altitude affecting the airplane's performance and cieling...but I was quickly assured that if I wanted to pass my oral I would believe that GPS at the MOCA was more than legal...so I shut my pie hole...

of course he's also the same guy that tried to bust me for using the "crab and kick" method coming in....I'm inbound on the approach and we pop out like (guessing) 300 feet above MDA so I hang out at MDA until I see the runway...when I do, I start a descent and configure the beast for landing:
him: "you better stay there if you want to pass"
me: (thinking of 91.175) "Yeah it would be a shame to bust a reg now"
him: "so get back up there"

so we continue in and I've got white over white but I'm affraid to descend
him: "Are you going to land tonight?"

so I'm on short final
him: "You know you're not lined up with the centerline"
me: (looking at the LOC needle which is centered) "I'll kick it out in the flare"
him: "YOU ARENT LINED UP WITH THE CENTERLINE - MY PLANE"
me: "your plane"
*SLAM* (side loaded - he didn't kick it out)
him: "I shouldn't pass you just for that stunt"
me: "my landings aren't being tested here"

totally pi$$ed me off...but oh well...

Rant over

-mini