FAA Instrument Rating Airplane (IRA)IFR Procedures and ChartsMedium
An en route low-altitude chart depicts a MOCA of 5,000 feet along a Victor airway, with no MEA shown for that segment beyond a certain point. According to 14 CFR Part 91, what does the MOCA guarantee to a pilot flying beyond 22 NM from the VOR?
- ANeither obstacle clearance nor signal reception beyond 22 NM
- BReliable NAVAID signal reception only, without guaranteed obstacle clearance
- CObstacle clearance only, without guaranteed navigation signal reception
- DBoth obstacle clearance and reliable NAVAID signal reception
Show answer & explanationAnswer & explanation
Correct answer: C. Obstacle clearance only, without guaranteed navigation signal reception
The MOCA guarantees obstacle clearance and acceptable navigational signal coverage only within 22 NM of the VOR. Beyond that distance, obstacle clearance is still guaranteed, but reliable signal reception is not, since the MOCA is calculated based on obstacle clearance requirements for the entire route segment.
Why the other options are wrong
- A. Incorrect—obstacle clearance is still guaranteed beyond 22 NM
- B. Incorrect—obstacle clearance is guaranteed for the entire segment at MOCA
- D. Incorrect because signal reception beyond 22 NM is not guaranteed at MOCA
MOCA (Minimum Obstruction Clearance Altitude)
The lowest published altitude that guarantees obstacle clearance for the entire route segment, but assures acceptable NAVAID signal coverage only within 22 NM of a VOR.
- MOCA is charted with a superscript asterisk on IFR en route charts
- Guarantees 1,000 ft (2,000 ft mountainous) obstacle clearance
- Signal reliability only assured within 22 NM of the VOR
Memory trick: MOCA: Obstacles always covered, signal only up close (22 NM).