class. In circumstances when a vessel is required to be continually on duty over a long period of time, common naval practice is to have at least three units of the type available to allow for replenishment, repair and overhaul. Three further vessels of the CS-50/Moss Sirius design were under construction or contract at the Severodvinsk Shipyard in Russia as of early 2007, but were configured for oil production. On 11 May 2011, Col. Mark Arn, the SBX project manager for MDA, said that the "SBX is the only one of its kind and there are no current plans for another one". In July 2011, a Missile Defense Agency spokesman explained that other, smaller radars in the Pacific will "pick up the slack" while SBX is in port with its radar turned off. Operational history The SBX deployed in 2006. The ship has spent time for maintenance and repair at Pearl Harbor, Hawaii several times, including 170 days in 2006, 63 days in 2007, 63 days in 2008, 177 days in 2009, and 51 days in 2010. When not at Hawaii, the SBX has been on operational deployments in the Pacific, including the waters off Alaska. The ship has not moored at Alaska, in spite of the construction of a $26 million, eight-point mooring chain system installed in 2007 in Adak's Kuluk Bay. On 23 June 2009, the SBX was moved to offshore Hawaii in response to a potential North Korean missile launch. Between 2009 and 2010, the vessel spent 396 continuous days at sea. The SBX failed during a flight test on 31 January 2010, designated FTG-06. The test was a simulation of a North Korean or Iranian missile launch. The test failure arose from two factors, the first being that algorithms in the SBX radar software (designed to filter out extraneous information from the target scene) were left disengaged for the test, and the second was a mechanical failure in a thruster on the kill vehicle. During flight test FTG-06a on 15 December 2010, the SBX performed as expected, but intercept of the target missile was again not achieved. In May 2011, the SBX-1 entered Vigor Shipyard (formerly the Todd Pacific Shipyard) in Seattle for a $27 million upgrade and maintenance work by contractor Boeing. The work was completed in about three months and in August 2011, SBX-1 departed Seattle for deployment. In December 2011, MDA transferred responsibility