Off-Route Obstruction Clearance Altitude (OROCA)
Off-Route Obstruction Clearance Altitude (OROCA) : An off-route altitude that provides obstruction clearance with a 1,000 foot buffer in nonmountainous terrain areas and a 2,000 foot buffer in designated mountainous areas within the U.S. This altitude may not provide signal coverage from ground based navigational aids, air traffic control radar, or communications coverage