Digital Map Error May Have Led To Minesweeper Grounding; Conditions Worsen (updated)


The Guardian remains hard aground on Tubbataha Reef in the Philippines. In this view from Jan. 19, the ship, which struck the reef bow-on, has been swung broadside to the reef by wind and waves. The reef is clearly visible in the foreground.


“Multiple spaces” are flooded aboard the minesweeper USS Guardian, still stranded on a reef in the Philippines since Jan. 17. While the ship’s condition remains stable, a U.S. destroyer has arrived on the scene in the Sulu Sea, and a salvage team headed by a rear admiral is being established as more ships and assets head to the area.

Weather conditions remain rough, and the ship, once pointed straight into the reef with her bow hard aground, has swung broadside on, where most of the starboard hull is in contact with the coral. As of Saturday evening Washington time, according to the Navy, the ship experienced a “slight increase to a port list,” but as of Sunday evening local time there is no evidence the ship is taking on more water.  Concerns persist, however, that the ship will sustain further damage.

No injuries have been reported, and the entire crew of 79 sailors was taken off the ship late Jan. 17 local time. As of Sunday night Jan. 20 local time, no one has been back on board the Guardian, the Navy confirmed.

On Jan. 18, the service revealed that a digital chart used by the ship to navigate in the region misplaced the location of a reef by about eight nautical miles, and may have been a significant factor when the ship drove on to the reef on Jan. 17.

As of Jan. 18, U.S. Navy ships have been directed to “operate with caution” when using similar electronic charts and compare the map data with paper charts, which are considered accurate.

Another view of the Guardian on Jan. 19. The ship's crew of 79 sailors was taken off on Jan. 18, and no one has been aboard the minesweeper since, although several ships are standing by to resume salvage operations.

Guardian sits bow on to the reef on Jan. 17, hours after she struck at 2:25 a.m. local time. (Armed Forces of the Philippines photo)

Crewmembers are visible on the Guardian's upper superstructure in this image taken Jan. 17. They were subsequently taken off the ship for safety reasons. The ship appears to have driven straight on to the reef, with its stern still in deeper water. (Armed Forces of the Philippines photo)

The Guardian drove onto Tubbataha Reef in the Sulu Sea around 2:25 a.m. on Jan. 17 (some sources cite a date of Jan. 16, since that was the date in Washington, D.C. when the incident occurred; there is a 13-hour time difference between Washington and the reef, with the Philippines 13 hours ahead of D.C.). The reef is about 80 miles east-southeast of Palawan Island in the western portion of the Philippine archipelago.

The ship had been at Olongapo City in Subic Bay, and was en route to Indonesia when she struck the reef, according to the Navy. Earlier plans for the ship to refuel at Puerto Princessa in Palawan Island were cancelled before the Guardian left Subic Bay, the Navy said, and media reports that the minesweeper was bound for Puerto Princessa when she struck the reef are incorrect.

The Guardian is homeported at Sasebo, Japan.

The mine countermeasures vessel, with a wooden hull sheathed in fiberglass, has been taking on water and moving on the reef, and 79 crew members were taken off the ship on Jan. 18, 45 transferring to the Navy survey ship Bowditch and 34 sailors to the C-Champion, a commercial vessel chartered by the Navy’s Military Sealift Command.

The Guardian has not been abandoned, the Navy said, and the service said removal of the crew was a temporary safety measure. But the ship remains threatened by the weather, according to the Navy official, and rough, unpredictable seas coming from different directions added to the ship’s movement on the reef.

Aerial surveys by U.S. Navy P-3C Orion maritime surveillance aircraft indicated no fuel leaks and no additional flooding on the ship by Sunday evening, a Navy official said, although the hull continues to be battered, particularly on the port side.

The Japan-based destroyer Mustin arrived on the scene on Jan. 19 and is assisting, the Navy official said, and a salvage assessment team is on board the Bowditch. On Sunday, 36 Guardian crewmembers were transferred to the Mustin, and as of Sunday evening, 35 sailors remain on the C-Champion with 8 on the Bowditch.

The Mustin departed the scene later on  Sunday for Puerto Princessa on Palawan Island to embark Rear Adm. Thomas Carney, commander of Task Force 73 and the U.S. Navy’s Singapore Area Commander, who will take charge of the salvage operation. The destroyer is expected to be back on scene with the Guardian by Monday Jan. 21.

A Philippine salvage tug, the Trabajador, also is on the scene and assisting, as is the Philippine Coast Guard. The salvage ship is equipped with environmental container booms but has been unable to deploy them in the rough weather. Conditions are expected to improve on Tuesday, and the booms will be deployed when the weather permits, the Navy said.

Forecasts for the region over the next one to two days are for 15-to-20-knot winds and four-to-six-foot seas. Conditions are expected to improve on Tuesday Jan. 22.

The Vos Apollo, an anchor-handling ship from Singapore, is expected to arrive at Puerto Princessa early Monday to load lighterage and oil recovery equipment for the salvage operation, the Navy said.

Other U.S. Navy teams are gathering at Puerto Princessa to assist the operation, including a Seabee detachment, technicians from the Southwest Regional Maintenance Center, and a Navy marine chemist.

The Pearl Harbor-based salvage ship Salvor also is en route, although she is not expected on the scene until late next week.

Digital Error

The Digital Nautical Charts (DNC) used by the Guardian and most Navy ships are produced by the National Geospatial-Intelligence Agency (NGA), a largely secret organization headquartered in Springfield,Va.

The DNC charts come in several versions. “General” and “coastal” versions are used in open areas such as the Sulu Sea, and “approach” and “harbor” versions are used for operating in and around harbors. According to an NGA memo sent to the Navy on Jan. 18, the error was in the coastal DNC, apparently in use on board the Guardian at the time of the grounding.

The general DNC and hardcopy charts show the reef’s location correctly, NGA said.

Letitia Long, the agency’s director, told the Navy that the coastal DNC chart for the Sulu Sea would be corrected by Jan. 30, and advised ships not to use DNC coastal charts in the area until then.

The Navy’s head navigator took things a step further, advising in a message sent to the fleet Jan. 18 “to operate with caution when using NGA-supplied Coastal Digital Nautical Charts due to an identified error in the accuracy of charting in the Sulu Sea.”

Rear Adm. Jonathan White, Oceanographer and Navigator of the Navy, said in the message that preliminary analysis of the error indicates it “resulted from incorrect geographic rectification of satellite imagery used to build” the coastal DNC charts.

“NGA has found no other anomalies, but is currently conducting a comprehensive review of its source data,” White said in the message.

He cautioned Navy ships “to compare coastal DNC charts with general DNC library charts, and not rely on [a] single source for navigation data.

“Commanding officers,” White added, “are directed to report any anomalies immediately to NGA.”

The agency expects to complete its review of all coastal DNC charts by Jan. 22, White noted.

A Navy official cautioned that while the digital chart error may have contributed to the incident, an accident investigation is continuing.

“This guidance to the fleet does not presuppose the cause of the USS Guardian grounding,” the official said Jan. 18. “The investigation will look at a number of potential contributing factors.”

The Guardian is commanded by Lt. Cmdr. Mark Rice, who first reported to the ship in October 2011.

The 14-ship minesweeper fleet, which generally toils in obscurity, has become the focus of major refurbishment and modernization efforts with the delay of planned replacements, renewed concerns about anti-mine capabilities, and a surge deployment to the Persian Gulf.

Guardian is one of four ships forward-deployed to Japan and is assigned to Mine Countermeasures Squadron 7. Four other mine countermeasures ships are homeported at Bahrain, where four San Diego-based ships also are operating. Two others remain at San Diego, home base for the mine force.

The ships entered service between 1987 and 1994.

Environmental Worries

The Guardian grounding triggered worries in the Philippines about potential damage to the coral reef, which is in a Unesco World Heritage zone where entry is restricted. Many local media are portraying the incident as an environmental issue, rather than a maritime accident.

No fuel leaks have been reported from the ship as of Sunday evening local time, but on Saturday, the U.S. Seventh Fleet commander issued a statement of regret regarding the grounding.

“As a protector of the sea and a sailor myself, I greatly regret any damage this incident has caused to the Tubbataha Reef,” said Vice Adm. Scott Swift. “We know the significance of the Tubbataha Reefs Natural Park and its importance as a World Heritage Site. Its protection is vital, and we take seriously our obligations to protect and preserve the maritime environment.”

In the statement, the Seventh Fleet declared that, “When the Guardian is safely recovered by the U.S. Navy, the U.S. government will continue to work with the Republic of Philippines government to assess the extent of the damage to the reef and the surrounding marine environment caused by the grounding. The Republic of the Philippines government was promptly informed of the incident and is being updated regularly by U.S. officials.”


The Guardian in happier times: Above, the ship heads out to sea in 2003 from her base at Sasebo, Japan, from where she's operated for most of her career. (U.S. Navy photos by by Photographer's Mate 2nd Class Jonathan Kulp)


Above and below, the ship arrives at White Beach, Okinawa on Jan. 8, 2013 for a refueling stop, eight days before grounding in Philippine waters. (U.S. Navy photos by Mass Communication Specialist 2nd Class Steve White)


Christopher P. Cavas
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Christopher P. Cavas

If it's on, over, under or around the water, I write about it. Ships and aircraft, units, tactics, leadership, strategies, acquisition, politics, industry. In the USA and around the world.
Christopher P. Cavas
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