Naval ships, designed to avoid detection by enemy fleets and aircraft, are exempt from an international requirement that vessels automatically and continuously broadcast their position, course and speed. They tend to have fewer lights than many commercial vessels, making them harder to pick out. They are painted gray to blend into the sea during wartime but become even more difficult to spot at night. And a growing number of modern naval vessels, including the John S. McCain, are designed to scatter incoming radar signals, so that they are less detectable.
Credit Joshua Fulton/U.S. Navy, via Getty Images
The Maritime and Port Authority of Singapore told The Straits Times, a Singapore newspaper, this week that the government’s vessel traffic information system had not even known the John S. McCain was there until the tanker, the Alnic MC, carrying 12,000 metric tons of fuel oil, delivered a crushing blow to the warship’s left side. Two sailors from the ship, a guided-missile destroyer, are dead, and eight more are listed as missing, as divers have begun discovering human remains inside the vessel’s mangled decks.
The Singaporean agency told The Straits Times that it had not detected the destroyer on radar and that its traffic information system had not picked up data on the ship. In addition to radar, traffic information systems rely on data from the so-called Automatic Identification Systems that all but the smallest commercial vessels are required to use to broadcast information about their whereabouts.
Military vessels typically carry the systems but often turn them off because the captains do not want to reveal so much information. The Maritime and Port Authority had no immediate comment or elaboration on its statement to The Straits Times. A United States Navy spokesman declined to comment on what systems were operating aboard the John S. McCain at the time of the accident, saying that the Navy’s focus remained on finding the missing sailors.
The difficulties with spotting naval vessels are amplified in busy waters — and those around Singapore are among the most crowded in the world because the city-state lies at the entrance to the Strait of Malacca, through which nearly all of East Asia’s oil imports and a large share of its seaborne exports move.
The congestion prompts military and commercial crews to turn off the early warning systems that alert them to potential collisions, said Capt. Harry Bolton, the director of marine programs at California State University Maritime Academy and a merchant marine officer who has traversed the waters near Singapore dozens of times.
Modern ship radars automatically calculate the closest point at which other vessels will approach them. The ship’s officers program the radars with a certain radius — typically one or two miles — and if any other vessel passes inside that radius, a beep begins sounding on the bridge.
Credit Christoph Van Der Perre/Reuters
The beeping can be switched off only when someone on the bridge hits a button to do so, acknowledging that the warning has been received. But bridge crews commonly turn off the systems near Singapore because other vessels are frequently less than a mile away, so the beeping would be almost continuous.
“You turn them off,” Capt. Bolton said. “I can see everything, and I can look on radar.”
But ships like the John S. McCain, a Burke-class destroyer, are considered among the Navy’s best examples of vessels with a smaller radar signature, according to several former officers. They are low to the waterline, with equipment masts tilted to the ship’s stern, rounded edges and no large “citadels” rising high off the deck, like those on cruisers.
While commercial vessels traversing the Strait of Malacca illuminate their hulls and the waters immediately around them so that they can spot any pirates who may be trying to climb aboard, heavily armed naval vessels with large crews have little to fear and are less lit up. Sometimes they appear like shadows moving among immense freighters resembling bright Christmas trees.
To better negotiate the Strait of Malacca, commercial ship captains sometimes dispatch two crew members to the bow with radios to tell bridge officers about hazards ahead, said Tim Huxley, the chairman of Mandarin Shipping, a Hong Kong shipping line.
Unlike the aviation industry, which also has to worry about congestion and collisions, the shipping industry has not instituted emergency avoidance systems.
Regulations in the United States, Europe and other large aviation markets require that the newest planes have electronic systems that communicate with each other almost instantly when a collision appears likely and recommend a coordinated response to the pilots. One pilot might be told, for example, to “climb, climb,” while the other might be told to “descend, descend.”