Minimum Altitudes

Question 1

What is the Off Route Obstruction Clearance Altitude (OROCA) and what does it provide?

Answer 1

OROCA provides 1,000 feet of clearance (2,000 in mountainous areas) within a quadrant 1 degree by 1 degree.

Question 2

What does the Minimum Enroute Altitude (MEA) assure?

Answer 2

MEA assures acceptable navigation signal coverage and obstacle clearance along an airway.

Question 3

What does the Minimum Obstruction Clearance Altitude (MOCA) assure?

Answer 3

MOCA assures obstacle clearance but only adequate signal within 22NM of either navaid.

Question 4

What is the Minimum Crossing Altitude (MCA)?

Answer 4

MCA is the altitude to cross a fix when proceeding to a higher MEA.

Question 5

What is the GNSS MEA?

Answer 5

GNSS MEA is the minimum altitude when using approved GPS.

Question 6

What is the Minimum Reception Altitude (MRA)?

Answer 6

MRA is the assigned signal coverage to identify an intersection with a cross radial.