MEA vs MOCA?

[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