MCA vs MOCA/MEA
- Thread starter Joffreyyy
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labbadabba
Pattern Altitude
If you're assigned the airway on lost coms the expectation is that you'll fly the MCA at JESSY, 13000 Northbound. Southbound you can be at JESSY 11000.
But why can I be lower then 13 going south ? I can’t use the MOCA? I don’t get your answer I’m not asking about lost comms I’m asking for a normal flight what is the lowest altitude I can use why have a MOCA if you must be at the MCA?
I saw it and was curious as to how they can have a MOCA which gives obstacle clearance that is lower then an MCA it doesn’t make sense to me why would you need to climb higher then a MOCA to clear an obstacle for MCA when the MOCA should give you the clearance ?
Clark1961
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At 13,000 ft he will prolly need oxygen. At 11,000 ft not so much. Knowing what altitude to plan for sorta matters. Learning how to read charts is sorta important too. Either reason is good enough to ask.
It’s sorta interesting to hear ATC concerns with altitudes out here. They will give you MEA and sometimes they wonder out loud if you can manage it.
nav or com reception problems. Missoula is in a sorta hole with terrain all around so that VOR is gonna have problems. ATC transmitter locations are also problems in the hills. They’ve made improvements over the years but there are still holes in the system.
Cooter
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Cooter
MOCA doesn’t guarantee reception outside of 22nm.
Cooter
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Cooter
The oxygen makes sense, didn’t think of that. But if I couldn’t fly the MEA, I wouldn’t fly it. Counting on only having to fly MOCA altitudes sounds like setting yourself up for trouble.
Clark1961
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Agree that requesting MOCA would prolly get an interesting response from ATC.
luvflyin
Touchdown! Greaser!
The MCA is part of the MEA thing that guarantees NAVAID reception. The MCA will guarantee you BOTH obstacle clearance and NAVAID reception. You don't need the MCA to clear the rocks in this case where there is both a MOCA and an MEA.
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RussR
En-Route
Just to be clear, I would make that "You don't need the MCA to clear the rocks IN THIS CASE." There are many cases where not making the MCA will indeed put you in the rocks.
luvflyin
Touchdown! Greaser!
Yeah. IN THIS CASE being edited into that post. thanks
BillTIZ
Final Approach
If I remember correctly. (IIRC)
MEA and MCA assures both ground clearance and the ability to receive ground based navigation signals.
The MOCA assures ground (obstruction) clearance, but not navigation.
You can navigate via own means or GPS.
The MCA 13000 at Jessy going north is to ensure navigation reception. They do not seemed to be concerned with it at Skott coming south as the expected climb rate to 13000 will keep you in Nav reception. Must be something going on at Jessy that blocks reception.
MEA and MCA assures both ground clearance and the ability to receive ground based navigation signals.
The MOCA assures ground (obstruction) clearance, but not navigation.
You can navigate via own means or GPS.
The MCA 13000 at Jessy going north is to ensure navigation reception. They do not seemed to be concerned with it at Skott coming south as the expected climb rate to 13000 will keep you in Nav reception. Must be something going on at Jessy that blocks reception.
SbestCFII
Line Up and Wait
The MEA = Obstruction clearance + NAV Reception while the MOCA is only Obstruction clearance and Reception within 22 NM of the VOR stations defining the airway. You can fly above the MOCA, at appropriate IFR/VFR cruise altitudes all day long with a GPS and never have an issue. However, remember that you can't actually cruise at the MOCA (8700) because of vertical seperation issues. The proper VFR/IFR altitude for direction of travel, which in this case just shy of due South (178-179) you would have to be at least 9000 IFR or 9500 VFR.
labbadabba
Pattern Altitude
You can use the MOCA if that is your clearance or if you're using the airway VFR. My assumption however was that your question was IFR-related since you referenced MEA/MCA/MOCA. If you're flying an airway IFR, it's because you're assigned and in that case the MCA altitudes will apply.
The reason I say lost comms is that is in large part the main driver of IFR procedures is to resolve a lost comms scenario. So when planning an IFR flight, (particularly over terrain with high MEAs and MCAs) I start with the assumption that a lost comms scenario is in-play and treat everything else as gravy.
One question I have for you, if you don't have a plane that's capable of flying 13,000 ft would you really be all that comfortable flying the MOCA in the clouds?
PaulS
Touchdown! Greaser!
Studying this now, in my mind, to answer this correctly on the test, if you have that flag with the X at a fix, you cross at at least the altitude associated with the flag or you get the answer wrong.
SbestCFII
Line Up and Wait
Correct!
drotto
Cleared for Takeoff
Yes, the X flag mean you must cross at the altitude indicated or higher. No X flag mean you can start your climb when you cross the point, you are not required to be at the new altitude yet.
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roncachamp
Final Approach
MEAs are established based upon obstacle clearance, NAVAID reception, and communications requirements. The communications requirement does not have to be direct pilot-controller, FSS relay is sufficient.