During the last year of World War II and shortly thereafter, the United States Navy acquired 48 ex-USAAF B-17s for patrol and air-sea rescue work. The first two ex-USAAF B-17s, a B-17F (later modified to B-17G standard) and a B-17G were obtained by the Navy for various development programs.[130] At first, these aircraft operated under their original USAAF designations but on 31 July 1945, they were assigned the naval aircraft designation PB-1, a designation which had originally been used in 1925 for the Boeing Model 50 experimental flying boat.[137]
Thirty-two B-17Gs[138] were used by the Navy under the designation PB-1W, the suffix -W airborne early warning. A large radome for an S-band AN/APS-20 search radar was fitted underneath the fuselage and additional internal fuel tanks were added for longer range, with the provision for additional underwing fuel tanks. Originally, the B-17 was also chosen because of its heavy defensive armament, but this was later deleted. These aircraft were painted dark blue, a standard Navy paint scheme which had been adopted in late 1944.[130][137] The PB-1W eventually evolved into an early warning aircraft by virtue of its APS-20 search radar.[138] PB-1Ws continued in USN service until 1955, gradually being phased out in favor of the Lockheed WV-2 (known in the USAF as the EC-121, a designation adopted by USN in 1962), a military version of the Lockheed 1049 Constellation commercial airliner.
In July 1945, 16 B-17s were transferred to the Coast Guard via the Navy; these aircraft were initially assigned U.S. Navy Bureau Numbers (BuNo), but were delivered to the Coast Guard designated as PB-1Gs beginning in July 1946.[130][133] Coast Guard PB-1Gs were stationed at a number of bases in the U.S. and Newfoundland, with five at Coast Guard Air Station Elizabeth City, North Carolina, two at CGAS San Francisco, two at NAS Argentia, Newfoundland, one at CGAS Kodiak, Alaska, and one in Washington state.[133] They were used primarily for air-sea rescue, but were also used for iceberg patrol duties and for photo mapping. Air-sea rescue PB-1Gs usually carried a droppable lifeboat underneath the fuselage and the chin turret was often replaced by a radome.[133][139] The Coast Guard PB-1Gs served throughout the 1950s, the last example not being withdrawn from service until 14 October 1959.[130][139]