A minimum off-route altitude (MORA) provides a quick way for an aircraft pilot to read the minimum altitude required for terrain and obstacle clearance.
[1] MORAs are given feet, rounded up to the nearest 100 and omitting the last two figures.
Route MORAs provide an obstacle clearance within 10 nautical miles (19 km) on both sides of the airways and within a 10-nautical-mile (19 km) radius around the ends of the airways.
An MEA gives a minimum altitude for reception of navigation aids and radio communications, and is found only within controlled airspace.
An OROCA gives 2000 feet of clearance only in mountainous areas.