Acho que 14 CFR Seção 91.205 (b) (12) define "sobre a água".
(12) If the aircraft is operated for hire over water and beyond power-off gliding distance from shore, approved flotation gear readily available to each occupant and, unless the aircraft is operating under part 121 of this subchapter, at least one pyrotechnic signaling device. As used in this section, “shore” means 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.
Em seguida, 14 CFR Seção 121.573 descreve os requisitos de briefing de passageiros para voos com operações sobre a água:
§121.573 Briefing passengers: Extended overwater operations.
(a) In addition to the oral briefing required by §121.571
(a), each certificate holder operating an airplane in extended overwater operations shall ensure that all passengers are orally briefed by the appropriate crewmember on the location and operation of life preservers, liferafts, and other flotation means, including a demonstration of the method of donning and inflating a life preserver.
(b) The certificate holder shall describe in its manual the procedure to be followed in the briefing required by paragraph (a) of this section.
(c) If the airplane proceeds directly over water after takeoff, the briefing required by paragraph (a) of this section must be done before takeoff.
(d) If the airplane does not proceed directly over water after takeoff, no part of the briefing required by paragraph (a) of this section has to be given before takeoff, but the entire briefing must be given before reaching the overwater part of the flight.
Por fim, a exigência de livretos de segurança impressos é de 14 CFR 121.571 (b) para responder a sua última pergunta, ela precisa ter apenas informações pertinentes ao vôo, portanto, se o avião não estiver sobrevoando a água, não é necessário.
(b) Each certificate holder must carry on each passenger-carrying airplane, in convenient locations for use of each passenger, printed cards supplementing the oral briefing. Each card must contain information pertinent only to the type and model of airplane used for that flight, including—
(1) Diagrams of, and methods of operating, the emergency exits;
(2) Other instructions necessary for use of emergency equipment; and
(3) No later than June 12, 2005, for Domestic and Flag scheduled passenger-carrying flights, the sentence, “Final assembly of this airplane was completed in [INSERT NAME OF COUNTRY].”