FAA Instrument Rating Airplane (IRA)IFR Procedures and ChartsEasy
A pilot is planning a direct GPS route between two airports that lies entirely off any charted federal airway, over mountainous terrain. The IFR en route low-altitude chart shows an Off-Route Obstruction Clearance Altitude (OROCA) of 12,500 feet for that quadrant. What does this altitude guarantee to the pilot?
- A1,000 feet of obstacle clearance and guaranteed radar coverage for ATC separation
- BThe minimum altitude ATC will assign for radar vectoring in that area
- C2,000 feet of obstacle clearance above the highest obstacle in the quadrant, but no assurance of navigation signal coverage
- DReliable VOR and GPS signal reception throughout the quadrant at that altitude
Show answer & explanationAnswer & explanation
Correct answer: C. 2,000 feet of obstacle clearance above the highest obstacle in the quadrant, but no assurance of navigation signal coverage
OROCA provides obstruction clearance only (1,000 ft in non-mountainous terrain, 2,000 ft in designated mountainous terrain) for operations off established airways. It does not assure navigation signal reception, communication reception, or ATC radar coverage.
Why the other options are wrong
- A. 1,000 ft applies only to non-mountainous terrain, and OROCA has nothing to do with radar coverage.
- B. OROCA is a charted planning altitude, not an ATC-assigned vectoring altitude.
- D. OROCA does not consider or guarantee any navigation signal reception.
OROCA
Off-Route Obstruction Clearance Altitude provides obstacle clearance for pilots operating off established airways or routes.
- 1,000 ft clearance in non-mountainous terrain
- 2,000 ft clearance in designated mountainous terrain
- Does not guarantee navigation signal or communication reception
- Found in the margins of en route low-altitude charts
Memory trick: OROCA: Obstacles cleared, but Reception Officially Cannot be Assured.