Low En-route Charts + Approach Plate Symbology

Question 1

Minimum IFR altitudes (91.177)

Answer 1

• Except for take off and landing, or otherwise authorized by the far, no person may operate an aircraft under IFR below:
• The minimum altitudes prescribed for the flown segment, or if none:
  1. Mountainous areas: 2,000 it above the highest obstacle within a horizontal distance of 4nm from the course.
  2. Non-mountainous areas: 1000 At above the highest obstacle within 4hm from the course

Question 2

DA

Answer 2

• decision altitude: the altitude (msl), on an Instrument approach at which point the pilot must decide whether to continue the approach or go around

Question 3

MAA

Answer 3

“Maximum authorized altitude’: “maa-17,000ft” (17,000 ft as an example) on IFR charts

Question 4

MDA

Answer 4

• minimum descent altitude: the lowest altitude (msl) to which descent is authorized on a non-precision approach until the pilot sees the usual references for landing.

Question 5

MEA

Answer 5

• minimum enroute altitude: the lowest published altitude between radio fixes that assure acceptable navigational signal coverage and meets obstacle clearance requirements. An MEA gap establishes an area of loss in navigational coverage and annotated “mea Gap” on IFR charts.

Question 6

MOCA

Answer 6

• minimum obstruction clearance altitude: provides obstacle clearance and navigation coverage only up to 22 nm of the VOR.
• if both MEA and a MOCA are prescribed for a particular route segment, a person may operate an aircraft lower than the MEA down to, but not below the MOCA, provided the applicable navigation signals are available. For aircraft using VOR for naviga ton, this applies only when the aircraft is within 22 nm of the VOR (91.177).

Question 7

MRA

Answer 7

Minimum reception altitude: the lowest altitude on an airway segment where intersection can be determined using radio navigational aids.

Question 8

MTA

Answer 8

Minimum turning altitude: previous vertical and lateral obstacle clearance in turns over certain fixes. Annotated with the MCA X icon and a note describing the restriction.

Question 9

OROCA

Answer 9

Off Route obstruction clearance altitude: provides obstacle clearance with a 1000 ft buffer in non-mountainous terrain areas and 2,000 ft in mountainous areas. OROCA may not provide navigational or communication signal coverage.