Which altitude is primarily concerned with off-route safety?

The correct answer is OROCA, which stands for Off-Route Obstruction Clearance Altitude. This altitude is specifically designed to provide a safe vertical clearance from obstructions in off-route areas, ensuring that an aircraft remains a safe distance above ground features and obstacles when not flying directly on a defined route. OROCA accounts for all known obstacles, providing a buffer that enhances safety for aircraft operating outside established airways.

In contrast, Minimum Obstruction Clearance Altitude (MOCA) provides clearance over obstacles on a specific route but does not extend the same level of safety when flying off the route. Minimum Reception Altitude (MRA) is concerned more with ensuring adequate reception of navigational aids within a defined airspace. Minimum Vectoring Altitude (MVA) is determined for the purpose of air traffic control to ensure safe separation between aircraft while in controlled airspace, but it does not specifically address obstructions outside route confines.