8900.1 CHG 0



Section 6   General Communication Concepts, Policies, and Guidance

4-126        GENERAL. For all operations, Title 14 of the Code of Federal Regulations (14 CFR) part 91 91.183 requires that the pilot in command (PIC) of each aircraft maintain a continuous watch on the appropriate frequency when operating under instrument flight rules (IFR) in controlled airspace. This section contains information and guidance concerning the communication equipment requirements for 14 CFR parts 121 and 135 over-water operations.



A.      Over-Water Operations. Title 14 CFR part 91 91.511 identifies the radio equipment that is required when operating over water more than 30 minutes flying time or 100 nautical miles (NM) from the nearest shore. Different from the extended over-water definition found in 14 CFR part 1, this term is applied to part 91 operations of large and turbine-powered multiengine airplanes.

B.      Extended Over-Water Operations. Part 1 defines extended over-water operation for airplanes as an operation over water at a horizontal distance of more than 50 NM from the nearest shoreline and for helicopters as an operation over water at a horizontal distance of more than 50 NM from the nearest shoreline and more than 50 NM from an off-shore heliport structure. The definition applies to both part 121 and 135 operations.

C.      Regulations. The appropriate regulations and accompanying guidance for conducting extended over-water operations under part 121 are as follows:

1)        Section 121.351(a) states that no person may conduct an extended over-water operation unless the airplane is equipped with the radio equipment necessary to comply with 121.349 and an independent system that complies with 121.347(a)(1).
2)        Section 121.349 requires all of the equipment required in 121.347(a) to be installed. In addition, the radio equipment must be able to satisfactorily receive all radio navigational facilities to be used by either of two independent systems.
3)        Section 121.347(a)(1) requires the radio equipment necessary for the crew to communicate with at least one appropriate ground station from any point en route.
4)        Section 121.347(a)(2) requires the radio equipment necessary for the crew to communicate with appropriate air traffic control (ATC) from any point in the control zone within which flights are intended.
5)        Section 121.347(a)(3) requires the radio equipment necessary for the crew to receive meteorological information from any point en route by either of two independent systems, and further states that one of the means provided to comply with this subparagraph may also be used to comply with subparagraphs (a)(1) and (2) of 121.347.

D.      Applicable Part 121 Guidance. To ensure adequate communication with ground stations, 121.351 requires part 121 operators engaged in extended over-water operations to have all aircraft equipped with two independent communication systems. Each of these independent communication systems must be capable of communicating with at least one appropriate ground station from any point on the route.

1)        If this requirement can be complied with on all over-water routes by using very high frequency (VHF) equipment, the airplane need only be equipped with two VHF receivers and two VHF transmitters.
2)        On the other hand, if compliance with 121.347(a)(1) can only be accomplished with high frequency (HF) equipment, the airplane must be equipped with two HF systems and at least one VHF system to also comply with 121.347(a)(2).

NOTE: Principal operations inspectors (POI) should be aware that Exemption No. 2081, as amended, grants relief from 121.99 by authorizing part 121 operators to dispatch airplanes over certain ocean areas with one of the two required HF radios inoperative at the time of departure, subject to certain conditions and limitations.

3)        The term appropriate ground station in 121.347(a)(1) includes, for example, aeronautical radio stations for ATC en route and air carrier dispatcher and flight-following services. Where there are gaps in air-ground communication capabilities that require the use of both VHF and HF systems en route to comply with 121.347(a)(1), there must be two VHF and two HF systems to comply with the requirement of 121.351.

E.      Part 135 Guidance. Section 135.165 prohibits operators from flying under IFR or on extended over-water operations unless the aircraft is equipped with certain communication and navigation equipment. Guidance for part 135 operators regarding this equipment is specified in 135.165 as follows:

1)        Section 135.165(a) pertains to turbojet airplanes with a passenger seating configuration of 10 or more and to multiengine airplanes carrying passengers as a commuter air carrier. Section 135.165(a) requires, in part, for IFR or for extended over-water operations, that those airplanes have radio communications equipment appropriate to the facilities to be used and that the equipment be capable of transmitting to, and receiving from, at least one ground facility at any place on the route. It also requires, in part, that two independent transmitters and two independent receivers for communication be used. For the purpose of this section, a receiver or transmitter is independent if it does not depend on the functioning of any part of another receiver or transmitter.
2)        Section 135.165(b) pertains to all other aircraft and requires, in part, only one transmitter and two independent receivers for communications under IFR or during extended over-water operations.
3)        Section 135.165(b)(7) also requires that an additional communications transmitter be used for extended over-water operations. This would mean that if an HF radio is required to communicate with ATC over any part of an extended over-water route, the aircraft will be required to be equipped with two independent HF transmitters and two independent HF receivers.

F.        Part 121 and 135 Operations Ferrying Aircraft Under Part 91. Section 91.511 requires those part 121 and 135 operators who ferry aircraft under part 91 to carry certain operable communications equipment on large and turbine-powered, multiengine airplanes when they are flown over-water. For example, when both VHF and HF communications equipment are required for the intended route under 91.511, 91.511(d) allows the part 91 operator to conduct over-water operations with only one HF transmitter and one HF receiver, provided the aircraft is equipped with two independent VHF transmitters and receivers. For part 135 operator aircraft ferried under part 91, which are not large, turbine powered multiengine airplanes, 91.205 governs.

4-129        DATA LINK. (TBD)

4-130        SATELLITE VOICE. (TBD)

RESERVED. Paragraphs 4-131 through 4-145.