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post #61 of Old 01-27-2013
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Re: US Navy ship strikes reef because of incorrect charts

Originally Posted by Boasun View Post
If the USN ship was using digital charts. There is no simple way to correct them....
I have digital chart on my boat and I have Identified quite a few errors... It seems that the people who produce them, either don't know what they are doing or just too lazy to correct any known errors. The key word in that last bit is "known."
I don't know, I'd tend to believe that the folks at The National Geospatial-Intelligence Agency (NGA) probably have a pretty fair idea of what they're doing, and doubt such an error would have been due to "laziness"...

Sounds like the error might possibly have occurred during the digitizing of the known charts in the Sulu Sea... I'd love to know how accurately existing paper charts place the reef, but I'd put my money on the likelihood that they're not 8 miles off... (grin)


While a review of the digital navigation charts (DNC) used by a U.S. 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.”

U.S. Navy: Charts Used By Grounded Minesweeper Are Safe | Defense News |
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