The minesweeper Guardian, seen here on Jan. 19, remains stranded on Tubattaha Reef in the Sulu Sea. (Armed Forces of the Philippines)
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More on the Guardian:
While a review of the digital navigation charts (DNC) used by a Navy minesweeper that grounded last week in the Philippines found one additional error, the charts were declared safe Wednesday by the Navy's top navigator.
"Ships should continue to confidently navigate with DNC, using all standard safe seamanship and navigation practices," Rear Adm. John White, navigator of the Navy, said in messages sent Jan. 23 to Navy ships, commands and flag officers.
The National Geospatial-Intelligence Agency (NGA), creator of the charts, conducted "a comprehensive analysis of all DNC libraries," White said in the message, and confirmed the error in the location of the Tubattaha Reef in the western Philippines, which the minesweeper Guardian struck in the early hours of Jan. 17.
The NGA reported earlier the location of the reef on the DNC charts was about eight nautical miles away from its true location.
"Additional significant errors" — up to four nautical miles — were found along the southwest coast of Chile, White reported in his messages. Those errors, he wrote, "are reflected on DNC and paper charts. NGA has issued warnings on those errors to all mariners."
The two inaccuracies "are the only known significant errors in the entire DNC portfolio of over 3,700 libraries," White wrote.
"No chart is infallible, but NGA's DNC remains the most accurate chart portfolio available."
The errors that were found came from the LANDSAT satellite survey images used to "geo-rectify" the digital charts, White wrote.
"Navy will be a key participant in a follow-on review of NGA's procedures to ensure the products and services associated with nautical charting continue to be safe and accurate," White said in the messages.
"I share NGA's high confidence that these errors are isolated, and that DNCs are overall safe for navigation."
Salvage Surveys Conducted
The Guardian remains hard on the reef in the Sulu Sea, a Navy official said Thursday morning local time, but shows no signs of additional damage. No signs of a fuel leak have been observed, the official said.
Salvage teams on Wednesday rigged hoses and lines for removing the ship's fuel and "conducted a satisfactory defueling test, but have not commenced defueling yet," the official said.
Waves in the area continue at about four-to-six feet, with isolated showers, and salvage teams are "working in pockets of isolated better weather to do these operations." Teams are getting on and off the ship via small boats.
The U.S. destroyer Mustin has returned to the scene, with Rear Adm. Thomas Carney, commander of Logistics Group Western Pacific in Singapore, as the on-scene commander.
The salvage teams "are working through a number of environmental response plans," the Navy official said and, in the next 24 hours, will "continue hydrographic survey and salvage planning.
Heavy lift cranes and other salvage and environmental containment equipment are en route from Singapore, but not expected to arrive for another week, the official added.
All of the Guardian's 79 crewmembers were taken off the ship on the evening of Jan. 17, and 69 sailors are now returning to their home port of Sasebo, Japan, on board the Navy oiler Rappahannock.
A ten-member "command element" from the Guardian remains on the scene, the Navy official said.
While Filipino organizations are not taking part in the salvage operations, they are actively monitoring the wreck scene, which is on a coral reef in a protected environmental zone.
The U.S., the Navy official said, remains in constant communication with the Filipinos, and "continues to keep the Philippine coast guard and government informed of our actions."