FAR 91.511 — Overwater Equipment
FAR 91.511 sets communication and navigation equipment requirements for airplanes flying over water more than 30 minutes or 100 NM from shore.
FAR 91.511 governs the communication and navigation equipment required when you fly an airplane over water more than 30 minutes flying time or 100 nautical miles from the nearest shore. The rule exists because if you lose a radio or nav unit far from land, you need backup to stay in contact with ATC and navigate safely back to shore.
Before taking off on such a flight, the airplane must have at least:
- Two transmitters
- Two microphones
- Two headsets, or one headset and one speaker
- Two independent receivers
- At least two independent electronic navigation units capable of navigating within ATC-assigned airspace
Independent means no part of one unit depends on another to function. A combined comm/nav receiver can count for both roles.
Key exceptions:
- Ferry flights with no passengers may depart with one of each dual item inoperative to reach a repair facility.
- If both VHF and HF are required and the airplane has dual VHF, only one HF transmitter and receiver are needed.
- In specified areas of the Gulf of Mexico, Caribbean, and western Atlantic, a single long-range nav system is acceptable if no more than a 30-minute VHF comm gap is expected.
Five FAA-written-style questions. Instant explanations, every answer cites its source — no account needed.
You are flying VFR in Class E airspace at 8,500 feet MSL during the day. What are your minimum visibility and cloud clearance requirements?