USNS Impeccable (T-AGOS-23): Wikis


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USNS Impeccable T-AGOS-23.jpg
USNS Impeccable
Name: USNS Impeccable
Owner: United States Navy
Operator: Military Sealift Command
Builder: American Shipbuilding, Tampa, Florida
Laid down: 15 March 1992
Completed: at Halter Marine Inc., Gulfport, Mississippi, in 1995
Launched: 28 August 1998
In service: 22 March 2001
Honors and
National Defense Service Medal
Status: in active service, as of 2010
General characteristics
Type: Impeccable-class ocean surveillance ship
Displacement: 5,368 tons
Length: 281 ft 5 in (85.78 m)
Beam: 95 ft 8 in (29.16 m)
Draft: 26 ft (7.9 m)
Propulsion: diesel-electric, two shafts, 5,000shp
Speed: 12 knots (22 km/h; 14 mph)
Complement: 25 civilian mariners, 25 military
Sensors and
processing systems:
SURTASS passive and active low frequency sonar arrays

USNS Impeccable (T-AGOS-23) is an Impeccable-class ocean surveillance ship acquired by the U.S. Navy in 2001 and assigned to the Navy’s Special Missions Program.



Impeccable was built by American Shipbuilding, Tampa, Florida. The contract was awarded on 28 March 1991. The ship's keel was laid down on 15 March 1992, but the Tampa shipyards went bankrupt by November 1993.[1] On 3 December 1992, the General Accounting Office published a report that concluded that T-AGOS 24-28 should not be built.[2]. Shortly afterwards the government decided to discontinue this class of ships, but the Impeccable was to be completed as the sole ship in its class. The hull was towed to Gulfport, Mississippi, in 1995 where it was finished by Halter Marine Inc.[3] She was launched on 28 August 1998 and was delivered to the Navy on 22 March 2001 which assigned her to the Military Sealift Command (MSC) Special Missions Program.[4]


The ship is a designated T-AGOS vessel built to tow a Surveillance Towed Array Sensor System. The ship's catamaran-type small waterplane area twin hull (SWATH) design prevents the vessel from rolling in heavy seas and gives additional deck space for storing the acoustic equipment.[5]


The mission of Impeccable is to directly support the Navy by using SURTASS passive and active low frequency sonar arrays to detect and track undersea threats.

Operational history


Low Frequency Active Sonar

  • The SURTASS Low Frequency Active Sonar system, onboard Impeccable, commenced sea trials in late February 2004. During the spring and summer of 2004, Impeccable conducted five training missions in the Philippine Sea and the northwest Pacific Ocean . All LFA sonar operations included the operation of the High Frequency / Marine Mammal Mitigation sonar and compliance with all mitigation requirements.[6]
  • Total operational days onboard the Impeccable using the LFA array:
(August 15, 2003 to August 15, 2004) 26.2 days with 63.0 hours of transmissions
(August 15, 2004 to August 15, 2005) 9.4 days with 22.7 hours of transmissions
(August 15, 2005 to August 15, 2006) 22.5 days with 39.4 hours of transmissions.[7]
  • The ship had five years of active and passive operations in the Western Pacific before the incident in the South China Sea.

South China Sea incident

Two Chinese trawlers stop directly in front of the Impeccable, forcing the ship to conduct an emergency "all stop" in order to avoid collision.

On March 8, 2009, the Impeccable, while monitoring submarine activity[8] 75 miles south of Hainan, China, was harassed by several Chinese Naval ships. The unarmed Impeccable was shadowed by five Chinese ships, including a Bureau of Maritime Fisheries Patrol Vessel, a State Oceanographic Administration patrol vessel, a Chinese Navy ocean surveillance ship, and two small Chinese-flagged trawlers, which maneuvered close to the Impeccable, with two closing in to 50 feet (15 m), waving Chinese flags, and ordering the Impeccable from the area.[9][10] The civilian crew sprayed water at one of the nearest Chinese ships; the Chinese sailors stripped down to their underwear and their vessel closed in to within 25 feet of the American ship. Shortly after the incident, the Impeccable radioed the Chinese crews, informing them of its intentions to leave the area, and requesting a safe pass to travel. When it was trying to leave the area, however, the two Chinese trawlers stopped directly in front of the Impeccable, forcing it to do an emergency stop to avoid a collision.[11][12] Once the Impeccable got underway, the crew aboard one of the Chinese ships used a grappling hook to try to snag Impeccable's towed sonar array.[13]

The Hainan Submarine Base is on the island of Hainan. The nearby Paracel Islands are administered by China, but claimed by both Vietnam and China

This was the latest in a string of incidents involving the Impeccable and Chinese vessels. On March 5, 2009, a Chinese frigate approached Impeccable, crossing its bow at a range of approximately 100 yards without first making contact. This was followed less than two hours later by a Chinese Y-12 aircraft, conducting 11 flyovers of Impeccable at an altitude of 600 feet (180 m) and a range from 100–300 feet (30–90 m). The frigate then crossed Impeccable's bow again, this time at a range of approximately 400–500 yards.[14][15]

One Chinese crewmen waves a Chinese flag, while another uses a grappling hook to try to snag Impeccable's towed sonar array.

On March 7, a Chinese intelligence collection ship contacted the Impeccable over bridge-to-bridge radio, calling her operations illegal and directing Impeccable to leave the area or "suffer the consequences."[16]

The United States lodged formal protests following the incident. Under international law, the U.S. military can conduct activities "in waters beyond the territorial sea of another state without prior notification or consent" including in an exclusive economic zone of another country, said a Pentagon spokesman. "The unprofessional maneuvers by Chinese vessels violated the requirement under international law to operate with due regard for the rights and safety of other lawful users of the ocean."[12][17]

The Chinese Foreign Ministry says the USNS Impeccable was conducting activities in China's Exclusive Economic Zone in the South China Sea. As such, it maintains that it may prohibit non-Chinese naval vessels from operating in this area. The United States claims that, according to the United Nations Convention on the Law of the Sea, China has no legal basis for restricting other nations' naval vessels' operations in this area.[18][19 ][20] Several legal experts also state that there is no legal foundation in China's claim that it can prevent foreign naval vessels from operating within its Exclusive Economic Zone.[21] The Foreign Ministry also said that the Pentagon's complaint that five Chinese vessels had harassed the Impeccable were "totally inaccurate".[19 ][22] China's claim has already been disputed by several released reports, which all state that the Impeccable was interfered with numerous times, both while operating in the area and when attempting to leave.[23][24][25].

On March 12, 2009, U.S. President Barack Obama gave the go ahead to send the guided missile destroyer USS Chung-Hoon (DDG-93) to the South China Sea to protect the Impeccable while operating in that area.[26][27][28]

Hans M. Kristensen of the Federation of American Scientists has suggested that the incident may be related to the classified Type 093 submarine that the Chinese navy had recently deployed in the area.[29]

Standard response

In similar incidents the United States has a standard formal response. Their Freedom of Navigation program challenges territorial claims on the world's oceans and airspace that are considered excessive by the United States. The United States position is an insistence that all nations must obey the international law of the sea as stated by the UN Law of the Sea Convention, though the United States has yet to ratify the treaty. Some coastal states make claims that the United States considers to be inconsistent with international law, which, if unchallenged, would limit navigational freedoms of the vessels and aircraft of the U.S. and other countries. The only case of a U.S. surveillance ship being captured was the USS Pueblo (AGER-2) in 1968.

Honors and awards

Impeccable personnel are qualified for the following medals:

See also


  2. ^ "Navy Continues to Build Ships Designed for Soviet Threat".  
  3. ^ "USNS IMPECCABLE (T-AGOS 23)". Naval Vessel Register. United States Navy. October 21, 2004. Retrieved 2009-03-11.  
  4. ^ Ship Inventory - USNS IMPECCABLE (T-AGOS 23) - Ocean Surveillance Ship, Military Sealift Command
  5. ^ T-AGOS 23 Impeccable - Swath-L (Large) Ocean Surveillance Ship
  6. ^ "Federal Register: August 25, 2005 (Volume 70, Number 164)".  
  7. ^ "SURTASS/LFA Final Report".  
  8. ^ Officials: Ship in China spat was hunting subs MSNBC 2009-03-10
  9. ^ Pentagon: Chinese vessels harassed unarmed ship, Associated Press, March 9, 2009
  10. ^
  11. ^ U.S. protests harassing of Navy ship by Chinese, MSNBC, March 9, 2009.
  12. ^ a b U.S. Protests 'Harassment' of Navy Ship by Chinese Vessels, Washington Post, March 9, 2009
  13. ^ Close call off South China Sea, MSNBC, March 9, 2009
  14. ^ USNS Impeccable: Chinese Vessels Harass US Navy Ship, March 9, 2009
  15. ^ Pentagon says Chinese vessels harassed U.S. ship, CNN
  16. ^ Chinese Vessels Harass U.S. Navy Ship, Pentagon Says, Bloomberg L.P., March 9, 2009
  17. ^ U.S. says Chinese vessels harassed Navy ship, Reuters, March 9, 2009
  18. ^ US And China Face-Off On The High Seas, Sky News, March 9, 2009
  19. ^ a b China hits out at US on navy row BBC News 2009-03-10
  20. ^ Chinese ships 'harass' US vessel, BBC News, 9 March 2009
  21. ^
  22. ^ Foreign Ministry says the USNS Impeccable violating international and Chinese law, Xinhua, March 10, 2009
  23. ^
  24. ^
  25. ^
  26. ^
  27. ^
  28. ^
  29. ^ US-Chinese Anti-Submarine Cat and Mouse Game in South China Sea

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.

External links


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