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.
In Plain English
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.
Regulation Text
14 CFR § 91.511§ 91.511 Communication and navigation equipment for overwater operations.
(a) Except as provided in paragraphs (c), (d), and (f) of this section, no person operating under this subpart may take off an airplane for a flight over water more than 30 minutes flying time or 100 nautical miles from the nearest shore unless it has at least the following operable equipment:
(1) Radio communication equipment appropriate to the facilities to be used and able to transmit to, and receive from, at least one communication facility from any place along the route:
(i) Two transmitters.
(ii) Two microphones.
(iii) Two headsets or one headset and one speaker.
(iv) Two independent receivers.
(2) Appropriate electronic navigational equipment consisting of at least two independent electronic navigation units capable of providing the pilot with the information necessary to navigate the airplane within the airspace assigned by air traffic control. However, a receiver that can receive both communications and required navigational signals may be used in place of a separate communications receiver and a separate navigational signal receiver or unit.
(b) For the purposes of paragraphs (a)(1)(iv) and (a)(2) of this section, a receiver or electronic navigation unit is independent if the function of any part of it does not depend on the functioning of any part of another receiver or electronic navigation unit.
(c) Notwithstanding the provisions of paragraph (a) of this section, a person may operate an airplane on which no passengers are carried from a place where repairs or replacement cannot be made to a place where they can be made, if not more than one of each of the dual items of radio communication and navigational equipment specified in paragraphs (a)(1) (i) through (iv) and (a)(2) of this section malfunctions or becomes inoperative.
(d) Notwithstanding the provisions of paragraph (a) of this section, when both VHF and HF communications equipment are required for the route and the airplane has two VHF transmitters and two VHF receivers for communications, only one HF transmitter and one HF receiver is required for communications.
(e) As used in this section, the termmeans that area of the land adjacent to the water which is above the high-water mark and excludes land areas which are intermittently under water.
(f) Notwithstanding the requirements in paragraph (a)(2) of this section, a person may operate in the Gulf of Mexico, the Caribbean Sea, and the Atlantic Ocean west of a line which extends from 44°47′00″ N / 67°00′00″ W to 39°00′00″ N / 67°00′00″ W to 38°30′00″ N / 60°00′00″ W south along the 60°00′00″ W longitude line to the point where the line intersects with the northern coast of South America, when:
(1) A single long-range navigation system is installed, operational, and appropriate for the route; and
(2) Flight conditions and the aircraft's capabilities are such that no more than a 30-minute gap in two-way radio very high frequency communications is expected to exist.
[Docket 18334, 54 FR 34314, Aug. 18, 1989, as amended by Amdt. 91-249, 61 FR 7190, Feb. 26, 1996; Amdt. 91-296, 72 FR 31679, June 7, 2007; Docket FAA-2022-1355, Amdt. 91-366, 87 FR 75846, Dec. 9, 2022]
Oral Exam Questions a DPE Might Ask
Q1When does FAR 91.511 require redundant communication and navigation equipment?
Per FAR 91.511(a), the redundant equipment is required before taking off on a flight over water more than 30 minutes flying time or 100 nautical miles from the nearest shore.
Q2What specific equipment must be installed for a Part 91 overwater flight beyond those limits?
FAR 91.511(a) requires two transmitters, two microphones, two headsets (or one headset and a speaker), two independent receivers, and at least two independent electronic navigation units appropriate for the route.
Q3What does 'independent' mean in the context of receivers and nav units under this rule?
Under FAR 91.511(b), a receiver or nav unit is independent if no part of its function depends on the functioning of any part of another receiver or nav unit.
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Related Sections in Part 91