A pilot is assigned the Minimum Obstruction Clearance Altitude (MOCA) of 4,500 feet for a Victor airway segment. The aircraft is currently 30 nautical miles from the VOR defining that airway. What limitation applies to using the MOCA at this distance?
- AMOCA cannot be used unless the aircraft is also above the MEA for that segment
- BMOCA only guarantees acceptable navigation signal reception within 22 nautical miles of the VOR; beyond that, signal reception may be unreliable even though obstacle clearance is still assured
- CMOCA is only valid for turbojet aircraft operating above FL180
- DMOCA guarantees reliable navigation signal reception at any distance from the VOR along the route
Show answer & explanationAnswer & explanation
Correct answer: B. MOCA only guarantees acceptable navigation signal reception within 22 nautical miles of the VOR; beyond that, signal reception may be unreliable even though obstacle clearance is still assured
Under 14 CFR 91.177, the MOCA provides obstacle clearance for the entire route segment but guarantees acceptable navigation signal coverage only within 22 nautical miles of the VOR. At 30 NM from the facility, obstacle clearance remains valid, but the pilot may not have reliable signal reception, unlike the MEA which guarantees both obstacle clearance and navigation signal reception throughout the segment.
Why the other options are wrong
- A. MOCA can be used as an assigned altitude below MEA under 91.177(a)(2) conditions without requiring MEA.
- C. MOCA applies to altitudes below 18,000 feet generally, not specifically to turbojets above FL180.
- D. MOCA does NOT guarantee signal reception beyond 22 NM from the VOR.
MOCA vs MEA (91.177)
The MOCA provides obstacle clearance for a route segment but only guarantees acceptable NAVAID signal reception within 22 NM of the VOR, unlike the MEA which guarantees both throughout the segment.
- MOCA = obstacle clearance for entire segment
- MOCA guarantees signal reception only within 22 NM of the VOR
- MEA guarantees both obstacle clearance and signal reception for the entire segment
Memory trick: '22 and Out' — MOCA's signal guarantee stops at 22 NM.