Instrument Altitudes

Question 0

MOCA

Answer 0

Minimum Obstruction Clearance Altitude - ensures reliable navigation only within 22 NM of facility and obstacle clearance.

Question 1

MEA

Answer 1

Minimum En-route Altitude- lowest published alt between radio fixes that guarantee adequate navigational signal reception and obstruction clearance of 1000 ft in non mountainous and 2000 in mountainous terrain

Question 2

MAA

Answer 2

Maximum Authorized Altitude - max usable altitude or flight level for an airspace structure or route segment for which adequate reception of navigation aid signals are assured

Question 3

MRA

Answer 3

Minimum Reception Altitude - lowest altitude in which an intersection can be determined

Question 4

MCA

Answer 4

Minimum Crossing Altitude - the lowest altitude at certain fixes at which an aircraft must cross when proceeding in the direction of higher minimum en route IFR altitude.

Question 5

OROCA (NOS)

Answer 5

Off Route Obstacle Clearance Altitude. Provides obstacle clearance of 1000 and 2000 ft but may not provide signal coverage from ground based nav aids, ATC radar , or communications.

Question 6

MSA

Answer 6

Minimum Safe/ Sector Altitudes - Found on approach plates provides 1000 ft terrain clearance with in 22 NM of the airport, used for emergency purposes.