DEFINITIONS (MINIMUM FLIGHT ALTITUDES)

Question 1

Minimum En-Route IFR Altitude (MEA)

Answer 1

The lowest published altitude (or flight level) between radio fixes that meets obstacle clearance requirements between those fixes and assures acceptable navigational and radio signal coverage. The MEA applies to the entire width of the airway, segment, or route between radio fixes defending the airway, segment, or route.

Question 2

Minimum Obstacle Clearance Altitude (MOCA)

Answer 2

The lowest published altitude (flight level) in effect between radio fixes on VOR airways, off-airways routes, or route segments, which meets obstacle clearance requirements for the entire route segment.

Question 3

Minimum Off-Route Altitude (MORA)

Answer 3

Route MORA values are computed on the basis of an area extending 10 NM to either side of the route centerline and including a 10 NM radius beyond the radio fix / reporting point or mileage break defining the route segment.

Grid MORA is an altitude computed by Jeppesen and the values are shown within each grid formed by the charted line of latitude and longitude. Figures are shown in thousands and hundreds of feet (omitting the last two digits so as to avoid chart congestion). Values followed by ± are believed not to exceed the altitudes shown.

MORA values clear all terrain or obstacle elevation (whichever is highest), by:
1,000 ft in areas where the highest reference points are 5,000 ft MSL, or lower;
2,000 ft in areas where the reference points are above 5,000 ft MSL.

Question 4

Minimum Safe / Sector Altitude (MSA)

Answer 4

MSA is the altitude depicted on instrument Approach, SID or STAR charts and identified as the minimum safe altitude which provides a 1,000 ft obstacle clearance within a 25 NM radius (or other value as stated) from the navigational facility upon which the MSA is predicated. When the MSA is divided into sectors, with each sector a different altitude, the altitudes in these sectors are referred to as “Minimum Sector Altitudes”.

Question 5

Minimum Vectoring Altitude (MVA)

Answer 5

The lowest MSL altitude at which an IFR aircraft will be vectored by a radar controller, except as authorised for Radar departures, approaches and missed approaches.
MVA Considerations:
MVA can be below MSA
MVA can provide only 1,000 ft obstruction clearance in designated mountainous areas.