MEAs that critical?

Ghery

Ghery

Touchdown! Greaser!
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Feb 25, 2005
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Olympia, Washington
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Ghery Pettit
I went for a quick XC flight yesterday. Severe clear, VFR flight. OLM-YKM-OLM via V204. 9500 MSL east bound, 10,500 MSL west bound. The MEA (had I been on in instrument clearance) is 10,000 MSL.

That's the background.

Picked up FF from SEA approach after leaving OLM. Got a squawk code and was radar identified. Continued my climb to 9500 MSL. Handed off to SEA center. I received several requests to ident, which I did, along with requests for my altitude. Seems they were having trouble with my transponder. At WHYTE V204 makes a bend and you switch from the OLM VOR to the YKM VOR. 57 DME from OLM, 50 DME from YKM. Before getting to WHYTE I lost the OLM VOR on Nav 1, but still had it on Nav 2. When I tuned the YKM VOR all I had was a loud tone on the frequency and no indication of the receiver picking it up. Both Nav radios had the same response. I'm flying VFR, visibility is unlimited, so what the heck. Got to WHYTE and turned to the heading to YKM (070). Set the DME to YKM and got no reading. Remember, I'm at 9500 MSL and the MEA is 10,000 MSL. When I got to about DME 45 or so from YKM the DME came alive. And I started getting a response from the nav radios. Chinook approach still had a problem with my transponder.

Came into YKM, shot a T&G and headed back to OLM. Got a new squawk code for FF for the trip home and Chinook approach was happy with the signal from my transponder. Climbed to 10,500 MSL and headed back across the Cascades. Now I'm 500 feet above the MEA, rather than 500 feet below it. DME worked all the way, nav radios worked all the way. Guided my along V204 to WHYTE and had a good signal from the OLM VOR before I got there. Still had a question from SEA center when I got out of the radar shadow from Mt Rainier about my location, but when I gave them my distance and vector from OLM they found me and seemed happy.

Long winded, but the bottom line is this. Was I having equipment problems, or is the MEA that touchy? I'd really like to know before I get my IR and fly that route in the clag some time.

Oh, and ATC in this part of the world is great. Even with the problems there was no hint of "squawk VFR, good day" until it was time to call the tower at OLM coming home. Great folks around here.
 
Ghery said:
Long winded, but the bottom line is this. Was I having equipment problems, or is the MEA that touchy? I'd really like to know before I get my IR and fly that route in the clag some time.

Oh, and ATC in this part of the world is great. Even with the problems there was no hint of "squawk VFR, good day" until it was time to call the tower at OLM coming home. Great folks around here.
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You said you went one way at 9500 and came back along the airway at 10500. Did you have problems coming back with the VOR reception at 57nm?

Are your antenna's clean? No oily grime?
Good connections from antenna to radio to display unit?

There are some high VFR quadrangles in the area, real close to Mt Ranier, but nothing really high along the airway to cause reception issues because of terrain.
 
BillTIZ said:
You said you went one way at 9500 and came back along the airway at 10500. Did you have problems coming back with the VOR reception at 57nm?

Are your antenna's clean? No oily grime?
Good connections from antenna to radio to display unit?

There are some high VFR quadrangles in the area, real close to Mt Ranier, but nothing really high along the airway to cause reception issues because of terrain.
Click to expand...

No problem with VOR reception coming home. I had the OLM VOR tuned and identified before WHYTE (57+ DME from OLM). The antennas are clean (we fly in the rain a lot around here. :D ). I can't speak to the connections. I have an e-mail off to the maintenance officer for this plane (club plane) describing what I experienced, as well.

As I noted, the MEA is 10,000 MSL over this route, so I was 500 below it east bound when the problems were noted and 500 above it when the VOR problems were not noted. Hence my question, just how touchy is the MEA?
 
Two thoughts:
Could have been a temperature inversion that was bending the radio signal on the way out, that then either dissipated or the temperature changed, during the time it took to make run out and then back to that mid point... We ham radio ops love the spring and fall when there are the temperature inversions that bend the VHF signals allowing us to communicate at longer distances than usual - but often block shorter range signals that we can normally work...

The other is that there is coupling between the two antennas that make reception more directional depending on the angle the signal is coming from...

But, since your transponder was also affected early in the flight but not later, I am leaning towards the temperature inversion that was changing with time - being that the transponder antenna is at a frequency nearly ten times higher than the VHF radios is not as likely to be affected by the vhf antennas...

denny-o
 
As we used to say in the Air Force, if the minimum wasn't good enough, it wouldn't be the minimum. Conversely, if something less than the minimum was good enough, that lesser value would be the minimum. I think you have effectively proven that 10,000 really is the minimum.
 
Ron Levy said:
As we used to say in the Air Force, if the minimum wasn't good enough, it wouldn't be the minimum. Conversely, if something less than the minimum was good enough, that lesser value would be the minimum. I think you have effectively proven that 10,000 really is the minimum.
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I disagree. Given the multitude of environmental and reception issues that can affect adequate quality of VOR signals I'd be really surprised to find that 200 ft would normally make the difference between a normal signal quality and an unusable one. And IMO, a key statement here is:

"When I tuned the YKM VOR all I had was a loud tone on the frequency and no indication of the receiver picking it up."

This suggests to me that Ghery was experiencing some kind of interference, either from his own airplane or from the ground.

Also, IME when one first enters an area below acceptable navigation signal coverage the indications are excessive needle wandering and occasional flags, not a complete loss of CDI function.
 
Keep in mind the automatic doubling of MEAs in designated "Mountainous areas."

Here locally that area extends a bit west of the actual "mountains." Therefore CLE CTR keeps you up at 5,000 when the airport is 1200' MSL. When available I cancel otherwise it's a rapid descent to MVA.
 
Ghery said:
Long winded, but the bottom line is this. Was I having equipment problems, or is the MEA that touchy? I'd really like to know before I get my IR and fly that route in the clag some time.
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I don't know the answer to your question, but if it makes you feel any better, I do know that the FAA flight checks airways for VOR reception. Details available here:

http://www.faa.gov/documentLibrary/media/Order/ND/8200.1C.pdf

11.21c(2):
All radials supporting instrument flight procedures must be checked for signal quality and accuracy. Fly Airways, Off-Airway Routes, or route segments throughout the length of the intended use, at or below the minimum requested altitudes. If these radials have procedural requirements beyond the Flight Inspection Standard Service Volume (FISSV) distance, they must be inspected to the additional distances at the minimum requested altitudes.


​
In this document, "instrument flight procedure means more than just instrument approaches (6.10):

Instrument flight procedures specify standard routings, maneuvering areas, flight altitudes, and visibility minimums for instrument flight rules (IFR). These procedures include airways, jet routes, off-airway routes, Standard Instrument Approach Procedures (SIAP(s)), Standard Instrument Departure Procedures/ Departure Procedures (SID(s))/ DP(s)), and Standard Terminal Arrival Routes (STAR(s)).
​
 
BillTIZ said:
You said you went one way at 9500 and came back along the airway at 10500. Did you have problems coming back with the VOR reception at 57nm?
Click to expand...

In case anyone is wondering about the use of VORs outside their service volumes, they are flight checked along the entire length of whatever airways are based on them, as mentioned in my preceding post.
 
dmccormack said:
Yes -- without any consideration for actual clearance.
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The higher required obstacle clearance in mountainous areas is hardly an "automatic doubling of MEAs". The actual obstacle clearance may be significantly more than the minimum required due to signal coverage and airspace issues.
 
roncachamp said:
The higher required obstacle clearance in mountainous areas is hardly an "automatic doubling of MEAs". The actual obstacle clearance may be significantly more than the minimum required due to signal coverage and airspace issues.
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"Automatic" as in "If it's deemed a 'mountainous area,' it's automatically afforded a 2000' clearance requirement."

Never mind that "mountainous areas" often have valleys, large plateaus, and actually end abruptly in some cases requiring higher MEAS when they are not actually warranted.

Clear it up fer ya? :rolleyes2:
 
dmccormack said:
"Automatic" as in "If it's deemed a 'mountainous area,' it's automatically afforded a 2000' clearance requirement."

Never mind that "mountainous areas" often have valleys, large plateaus, and actually end abruptly in some cases requiring higher MEAS when they are not actually warranted.

Clear it up fer ya? :rolleyes2:
Click to expand...

Well, since you've changed your original position in response to my message it seems I've cleared it up fer you.

You're welcome.
 
roncachamp said:
Well, since you've changed your original position in response to my message it seems I've cleared it up fer you.

You're welcome.
Click to expand...

Changed? :rolleyes2:

Changed what?

dmccormack said:
Keep in mind the automatic doubling of MEAs in designated "Mountainous areas."
Click to expand...

dmccormack said:
"Automatic" as in "If it's deemed a 'mountainous area,' it's automatically afforded a 2000' clearance requirement."

Never mind that "mountainous areas" often have valleys, large plateaus, and actually end abruptly in some cases requiring higher MEAS when they are not actually warranted.
Click to expand...

Nope, no change -- just more explanation for those who need that sort of thing.

:thumbsup:
 
MEA's don't "double" in mountainous area. What doubles in mountainous areas is the required obstruction clearance in the primary zone (normally 4nm either side of centerline) from 1000 feet to 2000 feet. If the MEA is driven by navaid reception rather than obstruction clearance, no change occurs in mountainous areas unless the greater primary zone requirement overcomes the reception requirement. In addition, the secondary zone obstruction clearance doesn't change -- it still slopes up from 500 feet at the outer edge of the primary zone to zero at the outer edge of the secondary zone (normally 2nm outside the primary zone).
 
dmccormack said:
Changed? :rolleyes2:

Changed what?
Click to expand...

Changed from "the automatic doubling of MEAs in designated 'Mountainous areas' " to "if it's deemed a 'mountainous area,' it's automatically afforded a 2000' clearance requirement."
 
dmccormack said:
That's not a "change" -- that's a restatement.
Click to expand...

Well, as the statements mean different things, it's actually a "change", not a "restatement".

Do you have any other questions about MEAs or the meanings of words?
 
dmccormack said:
Keep in mind the automatic doubling of MEAs in designated "Mountainous areas."
Click to expand...
Sorry, I don't follow this. I'm not even sure how you can tell what the MEA would have been in the same area if it hadn't been a "designated mountainous area", or did you mean something else?

Oh, okay, you must be referring to the required minimum obstacle clearance (1000 feet except in designated mountainous areas, where it's 2000).

Hopefully anyway.

edit: ugh. I should really read through to the end of the thread before posting. :(
 
dmccormack said:
1000 times two = (I'm thinking somewhere near -- doubled?)
Click to expand...
1000 feet is not the MEA -- it's the minimum obstruction clearance in the primary zone for enroute IFR flight in nonmountainous areas. MEA is the MSL altitude providing both minimum obstruction clearance and navaid reception. Different terms, different meanings. If an airway with an MEA of 8000 feet crosses the "mountainous" line, I guarantee that doesn't double the MEA to 16,000 feet, although it may drive it up to 9000 to meet the obstruction clearance requirement.

Discussions like this happen because people use a term with a specific meaning to describe something other than what it is officially defined to mean. This also confuses the heck out of trainees.
 
I knew what you originally meant Dan.
 
EdFred said:
I knew what you originally meant Dan.
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Ditto. As a "trainee" I have read the AIM, Pertinent IFR "FARS", FAA's Instrument handbook, Instrument procedures handbook, and even Bob Gardners Instrument pilot handbook. I tried to get thru Machaddo's book, but find his sense of humor insulting. Due diligence Ron.
 
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Ugh.

I just read Liz's post and realized I caused confusion -- mea culpa.

My apologies to Ron and Stephan.

CFR 91.117:
(i) In the case of operations over an
area designated as a mountainous area
in part 95, 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
(ii) In any other case, an altitude of
1,000 feet above the highest obstacle
within a horizontal distance of 4 nautical
miles from the course to be flown.
Click to expand...

My only point is that the 1000 minimum safe altitude over highest obstruction goes from 1000 to 2000 feet, no matter what the topography is in such designated areas.

This causes problems for us flying in from the east IFR, as we're miles past the last ridge before we're permitted to descend.
 
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