MEAsДЇor routes wholly contained within controlled airspace Radio fixes defining the airway, segment, or route. RNAV low or high route, or other direct route applies to theД®ntire width of the airway, segment, or route between the The MEA prescribed for a Federal airway or segment, The MEA is the lowest published altitude between radioДЇixes that assures acceptable navigational signal coverageДЄnd meets obstacle clearance requirements between thoseДЇixes. Note the mention of airspace buffers and communications requirements.ДЇrom the FAA's Instrument Procedures Handbook, on p. The question that I think you should ask is why is the MEA higher than the MOCA in some cases where you might not expect it, namely in the case of some GNSS MEAs.ДЇirstly, all MEAs take into account multiple factors, including those described in the following. MOCAs are determined essentially the same across the board. MOCAs provide minimum obstacle clearance, as you note MEAs also provide this-and more. If anyone could shed some light on how they come up the GPS MOCAs it would be appreciated. That makes even less sense to me.Дoes the GPS MOCA also take into account communication reception-but in that case why isnвЂ™t that mentioned in the regular MOCA definition? There are even T-Routes in Florida with a GPS altitude and a lower GPS MOCA. But I would think that the MOCA would do the same thing unless there was an MCA. If you fly at the MEA it guarantees that a normal climb will keep you above obstacles when entering the next segment with a higher MEA. I would think the GPS MEA would be the MOCA or even lower, since VOR reception isnвЂ™t required in the first 22 miles. HereвЂ™s a segment of a Victor Airway in Florida with a MOCA of 1300 but the MEA for GPS is 3000. VORs arenвЂ™t used in GPS navigation so I donвЂ™t understand why there would be a GPS MOCA on a T-Route or Victor Airway.Д®ven the example given in the Aeronautical Chart Users Guide (p56) has a GPS MOCA below the MEA. Signal coverage only within 25 statute (22 nautical) miles of a VOR. Routes, or route segments which meets obstacle clearance requirementsДЇor the entire route segment and which assures acceptable navigational

MINIMUM OBSTRUCTION CLEARANCE ALTITUDE (MOCA)в€’ The lowest publishedДЄltitude in effect between radio fixes on VOR airways, off-airway The Pilot Controller Glossary (and other places) define MOCAs as:

Moca aviation