Faulty map or navigation? In vast sea, USS Guardian smashes into tiny Tubbataha

Last Thursday, around 2:55 am, the USS Guardian —a United States Avenger-class minesweeping vessel— ran aground near the northern tip of Tubbataha reef’s south coral atoll. The site is one of 15 dive spots in Tubbataha, a marine park world-famous for its spectacular biodiversity. With the Amihan monsoon now in the area, each powerful wave sends the 68-meter boat smashing into the coral beneath it. The weather conditions make recovery efforts hazardous, as the US Navy contemplates lifting the boat off the reef and placing it on another ship.

 

Below is a map of the approximate site of the Guardian's grounding, based on the January 18 incident report of the Tubbataha Protected Area Management Board. Zooming out will show its distance from Puerto Princesa. Also shown are the inner and outer boundaries of the Reef, as defined by law (Republic Act 10067):

 

 

Reliance on charts, GPS

According to the US Navy, the USS Guardian was relying on inaccurate Digital Nautical Charts that "indicate(d) an error in the location of Tubbataha Reef" when it ran aground in the UNESCO-designated world heritage site and marine sanctuary on January 17.

However, the vessel's charts would have had to be off by at least 10 nautical miles (18.52 kilometers) —the width of the Tubbataha Reef buffer zone, as declared by law— for the crew to have continued to mistakenly believe that they were still outside the protected area when they ran aground. Aside from nautical charts, the US Navy relies on Global Positioning Systems (GPS) technology and other navigation technologies.  

But military-grade GPS has a margin of error of no more than 10 meters. And even if the ship had to rely on just civilian-grade GPS, the crew's reckoning would still have been no more than 40 meters off course.  In any case, some observers have questioned why the Guardian did not utilize alternative means of navigation —especially since most seafaring vessels, especially military ships, have multiple technologies in place to prevent such collisions.

Redundant systems, underwater visibility

 

“(The) US Navy has many redundant systems in place that can easily correct navigation errors,” said Jose Ma. Lorenzo Tan, preisdent of World Wildlife Fund – Philippines.  

Given the Guardian's "draft limit" —the maximum distance that the hull is allowed to sink below the water— the coral reef would have been just 12 feet below the water's surface for it to be able to strike the bottom of the boat. 

 

According to several diving websites, underwater visibility in the area of Tubbataha Reef can easily exceed 100 feet. This would have meant that the atoll should have been in plain sight to the Guardian's crew, even at night with powerful lights.  

In any case, the Convention on the International Regulations for Preventing Collisions at Sea (COLREGS) requires that "every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision."  

^{The USS Guardian on Tubbataha Reef, January 21. Note the visible coral beneath the ship. Photo: AFP Western Command}  

Explanation forthcoming? As of Tuesday evening, January 22, the US Navy has yet to explain the exact circumstances surrounding the USS Guardian's grounding.

 

Meanwhile, Vice Admiral Scott H. Swift, commander of the US 7th Fleet, said he regretted the incident.

 

“As a protector of the sea and a sailor myself, I greatly regret any damage this incident has caused to the Tubbataha Reef,” said Swift in a news release posted on the US 7th Fleet website. — With reporting by Rouch Dinglasan, map by Wayne Manuel, GMA News