USNS Big Horn (T-AO-198)
History
United States
Name	Big Horn
Namesake	The Bighorn River in Wyoming and Montana
Ordered	20 June 1988
Builder	Avondale Shipyard, Inc., New Orleans, Louisiana
Laid down	9 October 1989
Launched	2 February 1991
In service	21 May 1992
Identification	IMO number: 8812162 MMSI number: 368889000 Callsign: NBIG
Status	In active service
Badge
General characteristics
Class and type	Henry J. Kaiser-class replenishment oiler
Tonnage	31,200 DWT
Displacement	9,500 tons light Full load variously reported as 42,382 tons and 40,700 long tons (41,353 metric tons)
Length	677 ft (206 m)
Beam	97 ft 5 in (29.69 m)
Draft	35 ft (11 m) maximum
Installed power	16,000 hp (12,000 kW) per shaft 34,442 hp (25,683 kW) total sustained
Propulsion	Two medium-speed Colt-Pielstick PC4-2/2 10V-570 diesel engines, two shafts, controllable-pitch propellers
Speed	20 knots (37 km/h; 23 mph)
Capacity	178,000 to 180,000 bbl (28,300 to 28,600 m3) of fuel oil and jet fuel 7,400 sq ft (690 m2) dry cargo space; eight 20-foot (6.1 m) refrigerated containers with room for 128 pallets
Complement	103 (18 civilian officers, 1 U.S. Navy officer, 64 merchant seamen, 20 U.S. Navy enlisted personnel)
Armament	Peacetime: usually none Wartime: probably 2 × 20 mm Phalanx CIWS
Aviation facilities	Helicopter landing platform
Notes	Five refueling stations Two dry cargo transfer rigs

USNS Big Horn (T-AO-198) is a Henry J. Kaiser-class replenishment oiler of the United States Navy. Big Horn was laid down on 9 October 1989 and launched on 2 February 1991. The ship entered service with Military Sealift Command on 21 May 1992 as part of the United States Atlantic Fleet.

Big Horn, the twelfth ship of the Henry J. Kaiser class, was laid down at Avondale Shipyard, Inc., at New Orleans, Louisiana, on 9 October 1989 and launched on 2 February 1991. She entered non-commissioned U.S. Navy service under the control of the Military Sealift Command with a primarily civilian crew on 21 May 1992. She serves in the United States Atlantic Fleet.

This ship was one of several participating in disaster relief after the 2010 Haiti earthquake. Big Horn brought relief supplies to Haiti. During Operation Unified Response, Big Horn transferred 618 pallets of cargo and humanitarian assistance/disaster relief supplies and over 2,000,000 US gal (7,600,000 L) of fuel. Big Horn got underway from Naval Station Norfolk the day after the earthquake struck, arrived on scene in Haiti on 17 January and worked until being relieved by USNS Leroy Grumman on 11 February.^[1] In 2015, she refueled RFA Gold Rover in the South Atlantic.^[2]

In September 2024, she ran aground off Oman while with attached to USS Abraham Lincoln's strike group. The incident strained American logistics within the fleet amid rising tensions due to Israeli–Hezbollah conflict as she was the only oiler in the region. She was quickly brought into a local port, and no casualties or oil spills were reported; images showing flooding were released.^[3][4]

•  This article includes information collected from the Naval Vessel Register, which, as a U.S. government publication, is in the public domain. The entry can be found here.

• NavSource Online: Service Ship Photo Archive: USNS Leroy Grumman (T-AO-195)
• USNS Big Horn (T-AO 198)
• Wildenberg, Thomas (1996). Gray Steel and Black Oil: Fast Tankers and Replenishment at Sea in the U.S. Navy, 1912-1995. Annapolis, Maryland: Naval Institute Press. Retrieved 28 April 2009.