MEA vs MOCA?

[SkyBoy1981]

blah blah blah blah blah. So why prey tell is the MOCA on the chart to begin with?

And don't give me that 22 Nautical mile crap, cause they don't DELINIATE that distance on the freaking chart. Look at one, where do you see the 22 mile MOCA markings?...no where.

GRB offered MOCA, I TOOK IT. I can't help it if you never flew ifr except under a hood or with someone else who was responsible for the flight.

Real classy response there, sparky. I actually flew for 3 years as PIC in several turbine corporate aircraft prior to becomming a "regional puke", but thats neither here nor there. The 22nm is for radio reception only, as it states in the FAA's Instrument Flying Handbook. If one wishes to fly along in the soup only 1000ft above obstacles and terrain using only a GPS signal to keep them on the airway, I suppose you could fly around at MOCA. Is it legal? Sure, but is it smart? First off, what happens if you lose communications? According to the FAR's the absolute lowest altitude you can maintain after a loss of communications is MEA right? So now you're creating an unnecessary workload for yourself having to climb back to MEA while sorting out all of your other lost comm procedures. Then, as someone else mentioned, what happens if that almighty GPS craps out on you? Now you're stuck flying around in the blind until you can climb back up high enough to receive the VOR. I think the advice of any wise pilot would be to stay at or above MEA, unless safety prevents it. Perhaps you could use an ICC from someone, "regional puke" or not. Thanks for playing.

 

[Donsa320]

I don't think some of you folks have thought this through. The MOCA puts you BELOW the airway. The base of the airway and contolled airspace is 1200 ft except where the 700 ft "E" or surface "B, C, D & E" areas exist. Part 91 says you cannot operate below the MEA IFR except for take-off and landing and then that has to be in a Part 97 arrival or departure area. If you were down there groping along at the MOCA enroute you could expect VFR traffic, flying with a mile visibility clear of cloud, to mix it up with you. They'd be legal, you would not be. Our airline legal gurus said we could use the MOCA within 22 miles of the facility but offered no relief from the VFR traffic if the controlled airspace base was still 1200 ft out there. So best keep your eyes open I guess.

 

[FN FAL]

I don't think some of you folks have thought this through. The MOCA puts you BELOW the airway.

With all due respect, the MOCA raises the standard base of the AIRWAY...it does not lower it. And your ops specs don't apply to my use of the MOCA. I would see no reason for an airliner to use a MOCA to stay out of icing. In addition, your ops specs do not limit me from doing so in the type of operations I fly in.

Criteria for designating MOCA...

http://www.airspaceusa.com/MINIMUM OBSTACLE CLEARANCE ALTITUDE MOCA (en route criteria).htm

Defined in the Tall Structures Act of 1959....

http://www.msue.msu.edu/msue/imp/modla/pa259001.html

 

[satpak77]

Nice avatar, craptacular real life IFR experience...you'll make a great regional pilot.

and

To answer all of your questions...no, you freaking bone head.

and

choke yourself on my hand.

and

Hahaha...that's why I would never get an ICC from a regional puke.

and

blah blah blah blah blah.

Real professional posts in response to someones question re MOCA/MEA

MODERATORS: TAKE NOTE, you gonna tolerate this?

 

[Immelman]

what the hell are MEA and MOCA????????
the only thing i care about is the MVA (minimum vectoring altitude)

I was corrected above on this as I forgot MEA had nothing to do with radar... but the issue is that if you're in a non-turbo'd recip and/or without o2, there are a lot of MVAs out west that are untouchable to you (since I don't have an ATC chart witth MVAs printed on it I am going from experience). When you can't get radar at 12k' over 4000 ft terrain (6-7k mountains here and there) it is it something to care about.

 

[minitour]

The base of the airway and contolled airspace is 1200 ft except where the 700 ft "E" or surface "B, C, D & E" areas exist.

I'll agree with that. The airway starts at 1200 AGL...and is Class "E" airspace.

If you were down there groping along at the MOCA enroute you could expect VFR traffic, flying with a mile visibility clear of cloud, to mix it up with you. They'd be legal, you would not be.

uh...bearing in mind that the airway is Class E airspace (the whole airway including both sides of the centerline all the way down to 1200 AGL), how could VFR traffic be legal on an airway with a mile visibility?

Last I remembered was Class E requires 3-152 below 10k and 5-111 above 10k.

I can't believe if you were at MOCA skimming the bases there would be legal VFR traffic down there.

That, of course, assumes that people out there are always legal and...even someone with my low time knows that isn't always the case.

-mini

 

[FN FAL]

Real classy response there, sparky. I actually flew for 3 years as PIC in several turbine corporate aircraft prior to becomming a "regional puke", but thats neither here nor there.

I'd let you hold the yoke for while as I ate lunch as well...just so long as you didn't scare me too much and you can log it as you wish. Just don't be touching me...that's all I ask.

The 22nm is for radio reception only, as it states in the FAA's Instrument Flying Handbook. If one wishes to fly along in the soup only 1000ft above obstacles and terrain using only a GPS signal to keep them on the airway, I suppose you could fly around at MOCA. Is it legal? Sure, but is it smart?

Is it smart to fly in continious icing when the Airway allows a legal and safe option...NOOOO! Using your faulty syllogism, one would have to wonder why anyone would ever use invisible radio beams to pass within 100 feet of terrain on a precision approach...EGADDDS! For your sins, penance is five minutes here...PENANCE...log it as PIC if you want.

First off, what happens if you lose communications?

Yea...it's an emergency...screw the FARS, meet the need. If I'm at MOCA and VMC and I'm passing by an airport after radio failure, I'll land and call and cancel my IFR. If not near an airport, I'm going to meet my needs to the furthest limit of the law and then beyond. Do you think the FAA is going to MISS that three hundred feet difference between MOCA and MEA? I don't have to climb up into ICING conditions just because I lost radio...it's an emergency. Pilot IN Command may deviate. That's why holding a yoke and logging PIC does not a CAPTAIN make. Five more minutes penance here...PENANCE...remember, god is watching!

According to the FAR's the absolute lowest altitude you can maintain after a loss of communications is MEA right? So now you're creating an unnecessary workload for yourself having to climb back to MEA while sorting out all of your other lost comm procedures.

Climbing three hundred feet is workload? Heck, I bet you just about roll the plane over on a MISSED APPROACH! Five more minutes penance...PENANCE

Then, as someone else mentioned, what happens if that almighty GPS craps out on you? Now you're stuck flying around in the blind until you can climb back up high enough to receive the VOR. I think the advice of any wise pilot would be to stay at or above MEA, unless safety prevents it. Perhaps you could use an ICC from someone, "regional puke" or not. Thanks for playing.

If you look at federal law, the airway is 4 miles wide plus an additional 2 miles wide...I cite federal law. There is no crashing of a aircraft because the GPS craps out...you simply climb to MEA and make your mandatory report of nav loss OR you call the controller up and work out any "deals" that may be available...like this one, CANCEL IFR or how about a VECTOR!

Criteria for designating MOCA...

http://www.airspaceusa.com/MINIMUM%...20criteria).htm

Defined in the Tall Structures Act of 1959....

http://www.msue.msu.edu/msue/imp/modla/pa259001.html

Have a nice day!

 

[FN FAL]

and...

and...

and...

and...

Real professional posts in response to someones question re MOCA/MEA

MODERATORS: TAKE NOTE, you gonna tolerate this?

and...and...and...take a ride on the Big Rock Candy Mountains for your penance; at least until you know the lyrics!BIG ROCK CANDY MOUNTAINS by Burl Ives!
For you, the special Burl Ives addition!

 

[SkyBoy1981]

Did you not see where I stated that MOCA is to be used for an engine failure or any SAFETY RELATED situation that would prevent you from flying at MEA? I think that would include icing if you're in an aircraft not certified to be in it. My point was simple, fly at MEA unless its unsafe, then the minimum can be MOCA. What exactly IS your argument?

 

[Donsa320]

Fn Fal

Well, it seems to me that 91.177 (a)(2)(ii) says exactly what I just did. You cannot drop down to the MOCA until within 22 NM of the station. I guess I can't read English if it does not say that. Of course if you are saying that in some sort of emergency you can use the MOCA further out, then yes you can. So what is the disagreement?

If you were around before 1960, before AOPA got this stuff pushed through...ie; base of the airway 1200 ft, 700ft transition areas and all the rainbow colors on the sectional/WAC charts etc, you would have seen that the MEA's were established with the pure 1,000 ft obstruction clearance as a criteria with nav reception a secondary consideration. On the Low Frequency airways line of sight was not needed so even that seldom raised the MEA. AOPA's aim was to give the scud runners a little more room, plain and simple. So the base of the airways now is 1200 ft and the MOCA gives you 1,000 ft obstacle clearance. The MEA gives you nav reception and keeps you on the airway (1200 ft floor) and MOCA does not.

No, "airliners" are not running around at the MOCA. This discussion I thought was about normal operations for everyone. In my opinion, 91.177 is quite clear. In non emergency operations you cannot use the MOCA IFR unless within 22nm of the station. You, of course, can do what ever you want.

-DC

 

[Donsa320]

I'll agree with that. The airway starts at 1200 AGL...and is Class "E" airspace.




uh...bearing in mind that the airway is Class E airspace (the whole airway including both sides of the centerline all the way down to 1200 AGL), how could VFR traffic be legal on an airway with a mile visibility?

Last I remembered was Class E requires 3-152 below 10k and 5-111 above 10k.

I can't believe if you were at MOCA skimming the bases there would be legal VFR traffic down there.

That, of course, assumes that people out there are always legal and...even someone with my low time knows that isn't always the case.

-mini

Have you got it figured out yet Mini....it is legal to fly below the airway VFR which is "G" airspace and you only need that 1 mile clear of cloud below 1200 ft, which all you guys recite so religiously, but I wonder if you know what it means. The MOCA is down there too. Below the airway.

-DC

 

[minitour]

Have you got it figured out yet Mini....it is legal to fly below the airway VFR which is "G" airspace and you only need that 1 mile clear of cloud below 1200 ft, which all you guys recite so religiously,

Sure, you can fly VFR below the airway in class "G" airspace.

but I wonder if you know what it means. The MOCA is down there too. Below the airway.

-DC

I've got it figured out, but I think you need to combine the rote knowledge on MOCA with the 1,200' AGL base of the airway and see what's going on.

Lets review...the MOCA gives you 1,000' obstruction clearance in non-mountainous areas, 2,000' obstruction clearance in designated mountainous areas and navaid reception up to 22nm from the facility.

So lets just assume that you've got an obstruction which stands 500' AGL and you're in a nonmountainous area. Your MOCA couldn't be any lower than 1500AGL (on the airway and in Class E airspace). If you've got 1sm and you're just below the clouds at this MOCA, you would not run into legal VFR traffic.

Of course, if you had no obstructions in a non-mountainous area, you could have a MOCA down to the bottom of the airway...but even then, VFR traffic wouldn't be legal in the 1sm situation previously described...because they'd be in Class E airspace on the airway if they were at the MOCA.

m'kay?

-mini

 

[Donsa320]

Mini

I don't think so...in your case the MEA would be at least 1700 Ft would it not? 1200 ft AGL means above everything that is surveyed unless it is in a terminal area I believe. I will delve into your point, though, but not tonight.

-DC

 

[minitour]

I don't think so...in your case the MEA would be at least 1700 Ft would it not? 1200 ft AGL means above everything that is surveyed unless it is in a terminal area I believe. I will delve into your point, though, but not tonight.

-DC

Why would the MEA give you another 500'?

MEA and MOCA are the same except MEA guarantees you NAVAID reception. MOCA only gives you 22nm of NAVAID reception.

-mini

*edit*
I see what you're getting at now...roger

 

[jackotron]

...wouldn't this be a mute point?

Don't you mean a "moot" point? I'm a little confused.

Jack

 

[FN FAL]

Don't you mean a "moot" point? I'm a little confused.

Jack

Don't waste your time...next think you know, these jackalopes will turn you buggy too...MUHAHAHAHAHAHAHAHA!

 

[100LL... Again!]

With GPS becoming more prevalent, I am betting that the 22nm reg will go away at some point for /G filers. Not to mention that ATC can clear you to whatever altitude their chart shows for your area. If ATC clears me there and it does not conflict with the OROCA or MORA (Jepp), then I feel just fine going there.

If the MOCA is safe within 22nm, it's safe along the whole route.

It is VERY IMPORTANT to remember that the regs are a very poorly thought out set of rules. There are many cases that can be posited that have no good answer in the regs. That is where the responsibility and authority of the PIC comes in.

 

[FN FAL]

Why would the MEA give you another 500'?

MEA and MOCA are the same except MEA guarantees you NAVAID reception. MOCA only gives you 22nm of NAVAID reception.

-mini

*edit*
I see what you're getting at now...roger

How could a navaid not give 22 nm of service volume at 1,200 AGL? What turd would buy that VOR?

here's some more stuff to chew on...



Q: "I have a question about victor airway lengths as compared to VOR service volumes. Perhaps you can find someone for me who can give me a firm answer.

Occasionally I see a victor airway whose length exceeds what would be covered by the standard service volumes of the VORs on the two ends.

For example, V499 from Binghamton to Lancaster is over 100 nm long, even though the service volumes of the VORs on the ends imply that the airway should not be more than 80 nm long.

In other words, there is a sizeable segment in the center of the airway which, theoretically speaking, is not covered by either of the two VORs.

Is there a technical standard that governs when it is permitted to define an airway in this way, and if so, could I get a look at the standard and have someone explain it to me?

A: It is true that most electronic navigational aids have a standard service volume. A description of navigational aids and standard service volumes can be found in the Aeronautical Information Manual, Chapter 1. I direct your attention to Paragraph 1-1-8:

1-1-8. Navigational Aid (NAVAID) Service Volumes

a. Most air navigation radio aids which provide positive course guidance have a designated standard service volume (SSV). The SSV defines the reception limits of unrestricted NAVAID's which are usable for random/unpublished route navigation.

b. A NAVAID will be classified as restricted if it does not conform to flight inspection signal strength and course quality standards throughout the published SSV. However, the NAVAID should not be considered usable at altitudes below that which could be flown while operating under random route IFR conditions (14 CFR Section 91.177), even though these altitudes may lie within the designated SSV. Service volume restrictions are first published in Notices to Airmen (NOTAM's) and then with the alphabetical listing of the NAVAID's in the A/FD.

c. Standard Service Volume limitations do not apply to published IFR routes or procedures.

In paragraph "c" you will note that "Standard Service Volume limitations do not apply to published IFR routes or procedures." Published routes are verified by FAA flight inspection aircraft before they are published and then periodically thereafter. If the published route does not meet the quality requirements necessary for reliable navigation, restrictions may be required. The minimum reception altitude may be raised, or the changeover point may have to be moved. A good example of this is Victor 2 between Rochester and Syracuse. Even though the Syracuse VORTAC is an "H" class, the standard service volume below 14,500' MSL is still 40 nautical miles. The changeover point on Victor 2 (Lorth) is 52 nm from Syracuse (beyond the standard service volume). This was necessary to make Victor 2 useable below 6,000' MSL, due to limitations on the Rochester VORTAC. You may also notice that the Rochester VORTAC is used as a high altitude fix, even though it's standard service volume only goes to 18,000' MSL. When the Kleinberg (near Toronto) VORTAC was de-commissioned, another navaid was needed to define Jet Route 522 and the KLOPS intersection. An "expanded use" flight inspection was conducted for the Rochester VORTAC and it was determined to be acceptable for use at high altitudes within the confines of J522.

You may also be interested to know that ATC may assign a direct route to any navaid even though the distance exceeds the standard service volume for that navaid. This can be done only when the route will remain within the radar coverage of ATC and ATC will maintain radar monitoring."

 

[100LL... Again!]

You can navigate by your mood watch as long as you are under radar surveillance.

"Denver Center, my mood watch recommends a heading of 180".

Roger, cleared as requested.

 

[minitour]

Good read FN! Good stuff