On 20 February 1974, the S-3A officially became operational with the Air Antisubmarine Squadron FORTY-ONE (VS-41), the "Shamrocks," at NAS North Island, California, which served as the initial S-3 Fleet Replacement Squadron (FRS) for both the Atlantic and Pacific Fleets until a separate Atlantic Fleet FRS, VS-27, was established in the 1980s. The first operational cruise of the S-3A took place in 1975 with the VS-21 "Fighting Redtails" aboard USS John F. Kennedy.
Starting in 1987, some S-3As were upgraded to S-3B standard with the addition of a number of new sensors, avionics, and weapons systems, including the capability to launch the AGM-84 Harpoon anti-ship missile. The S-3B could also be fitted with "buddy stores", external fuel tanks that allowed the Viking to refuel other aircraft. In July 1988, VS-30 became the first fleet squadron to receive the enhanced capability Harpoon/ISAR equipped S-3B, based at NAS Cecil Field in Jacksonville, Florida. 16 S-3As were converted to ES-3A Shadows for carrier-based electronic intelligence (ELINT) duties. Six aircraft, designated US-3A, were converted for a specialized utility and limited cargo COD requirement. Plans were also made to develop the KS-3A carrier-based tanker aircraft to replace the retired KA-6D Intruder, but this program was ultimately cancelled after the conversion of just one early development S-3A.
With the collapse of the Soviet Union and the breakup of the Warsaw Pact, the Soviet-Russian submarine threat was perceived as much reduced, and the Vikings had the majority of their antisubmarine warfare equipment removed. The aircraft's mission subsequently changed to sea surface search, sea and ground attack, over-the-horizon targeting, and aircraft refueling. As a result, the S-3B after 1997 was typically crewed by one pilot and one copilot; the additional seats in the S-3B could still support additional crew members for certain missions. To reflect these new missions the Viking squadrons were redesignated from "Air Antisubmarine Warfare Squadrons" to "Sea Control Squadrons."
Prior to the aircraft's retirement from front-line fleet use aboard US aircraft carriers, a number of upgrade programs were implemented. These include the Carrier Airborne Inertial Navigation System II (CAINS II) upgrade, which replaced older inertial navigation hardware with ring laser gyroscopes with a Honeywell EGI (Enhanced GPS Inertial Navigation System) and added digital electronic flight instruments (EFI). The Maverick Plus System (MPS) added the capability to employ the AGM-65E laser-guided or AGM-65F infrared-guided air-to-surface missile, and the AGM-84H/K Stand-off Land Attack Missile Expanded Response (SLAM/ER). The SLAM/ER is a GPS/inertial/infrared guided cruise missile derived from the AGM-84 Harpoon that can be controlled by the aircrew in the terminal phase of flight if an AWW-13 data link pod is carried by the aircraft.
The S-3B saw extensive service during the 1991 Gulf War, performing attack, tanker, and ELINT duties, and launching ADM-141 TALD decoys. The aircraft also participated in the Yugoslav wars in the 1990s and in Operation Enduring Freedom in 2001.
The first ES-3A was delivered in 1991, entering service after two years of testing. The Navy established two squadrons of eight ES-3A aircraft each in both the Atlantic and Pacific Fleets to provide detachments of typically two aircraft, ten officers, and 55 enlisted aircrew, maintenance and support personnel (which comprised/supported four complete aircrews) to deploying carrier air wings. The Pacific Fleet squadron, Fleet Air Reconnaissance Squadron FIVE (VQ-5), the "Sea Shadows," was originally based at the former NAS Agana, Guam but later relocated to NAS North Island in San Diego, California with the Pacific Fleet S-3 Viking squadrons when NAS Agana closed in 1995 as a result of a 1993 Base Realignment and Closure (BRAC) decision. The Atlantic Fleet squadron, the VQ-6 "Black Ravens," were originally based with all Atlantic Fleet S-3 Vikings at the former NAS Cecil Field in Jacksonville, Florida, but later moved to NAS Jacksonville, approximately 10 miles (16 km) to the east, when NAS Cecil Field was closed in 1999 as a result of the same 1993 BRAC decision that closed NAS Agana.
The ES-3A operated primarily with carrier battle groups, providing organic ‘Indications and Warning’ support to the group and joint theater commanders. In addition to their warning and reconnaissance roles, and their extraordinarily stable handling characteristics and range, Shadows were a preferred recovery tanker (aircraft that provide refueling for returning aircraft). They averaged over 100 flight hours per month while deployed. Excessive utilization caused earlier than expected equipment replacement when Naval aviation funds were limited, making them an easy target for budget-driven decision makers. In 1999, both ES-3A squadrons and all 16 aircraft were decommissioned and the ES-3A inventory placed in Aerospace Maintenance and Regeneration Group (AMARG) storage at Davis-Monthan AFB, Arizona.
Though a proposed airframe known as the Common Support Aircraft was once advanced as a successor to the S-3, E-2 and C-2, this plan failed to materialize. As the surviving S-3 airframes were forced into sundown retirement, a Lockheed Martin full scale fatigue test was performed and extended the service life of the aircraft by approximately 11,000 flight-hours. This supported Navy plans to retire all Vikings from front-line Fleet service by 2009 so new strike fighter and multi-mission aircraft could be introduced to recapitalize the aging Fleet inventory, with former Viking missions assumed by other fixed-wing and rotary-wing aircraft.
In March 2003, during Operation Iraqi Freedom, an S-3B Viking from Sea Control Squadron 38 (The "Red Griffins") piloted by Richard McGrath Jr. launched from USS Constellation (CV-64). The crew successfully executed a time sensitive strike and fired a laser-guided Maverick missile to neutralize a significant Iraqi naval and leadership target in the port city of Basra, Iraq. This was one of the few times in its operational history that the S-3B Viking had been employed overland on an offensive combat air strike and the first time it launched a laser-guided Maverick missile in combat. The first time an S-3B was employed overland during an offensive air strike was during Operation Desert Storm when an aircraft from VS-24, from the USS Theodore Roosevelt (CVN-71), attacked an Iraqi Silkworm missile site.
On 1 May 2003, US President George W. Bush flew in the co-pilot seat of a VS-35 Viking from NAS North Island, California to USS Abraham Lincoln off the California coast. There, he delivered his "Mission Accomplished" speech announcing the end of major combat in the 2003 invasion of Iraq. During the flight, the aircraft used the customary presidential callsign of "Navy One". The aircraft that President Bush flew in was retired shortly thereafter and on 15 July 2003 was accepted as an exhibit at the National Museum of Naval Aviation at NAS Pensacola, Florida.
Between July and December 2008 the VS-22 Checkmates, the last sea control squadron, operated a detachment of four S-3Bs from the Al Asad Airbase in Al Anbar Province, 180 miles (290 km) west of Baghdad. The planes were fitted with LANTIRN pods and they performed non-traditional intelligence, surveillance, and reconnaissance (NTISR). After more than 350 missions, the Checkmates returned to NAS Jacksonville, Florida on 15 December 2008, prior to disestablishing on 29 January 2009.
The final carrier based S-3B Squadron, VS-22 was decommissioned at NAS Jacksonville on 29 January 2009. Sea Control Wing Atlantic was decommissioned the following day on 30 January 2009, concurrent with the U.S. Navy retiring the last S-3B Viking from front-line Fleet service.
In June 2010 the first of three aircraft to patrol the Pacific Missile Test Center's range areas off of California was reactivated and delivered. The jet aircraft's higher speed, 10 hour endurance, modern radar, and a LANTIRN targeting pod allow it to quickly confirm the test range being clear of wayward ships and aircraft before tests commence. These S-3Bs are flown by Air Test and Evaluation Squadron Thirty(VX-30) based out of NAS Point Mugu, CA.
Also, the NASA Glenn Research Center acquired four S-3Bs in 2005. Since 2009, one of these aircraft (USN BuNo 160607) has also carried the civil registration N601NA and is used for various tests.