In what now appears to have been a tragic freak accident, the Los Angeles-class nuclear powered fast-attack submarine hit an uncharted undersea mountain. At the time, San Francisco was moving at high speed, while submerged, on her way from Guam (a U.S. Territory and her home port) to Australia. The accident occurred 350 miles south of Guam. This would put her near the Federated States of Micronesia, also known as the Caroline Islands, a chain of mid-Pacific Ocean atolls of volcanic origin just north of the equator. Sadly, one crewman later died from serious head trauma, and about two dozen other men were hurt too badly to be able to stand watch. These injuries occurred when people were suddenly thrown against unyielding metal equipment, or hurled from their sleeping racks or knocked off their feet, by the force of the crash. San Francisco surfaced immediately, and returned to Guam under her own power, her nuclear reactor and propulsion plant undamaged. U.S. Navy ships and aircraft rushed to assist, and emergency medical personnel (including at least one M.D.) transferred aboard while she was still at sea.

It’s natural to ask how and why an accident of this nature could occur.

Before I go on, some disclaimers: Further information will be determined, and might (or might not) be declassified, in the days and weeks to come. This essay is based on unclassified news releases as of January 11, 2005, tempered by my knowledge of the open literature concerning American submarine operations and procedures, the unclassified portions of my four days at sea on another Los Angeles-class vessel, plus logical inference and informed speculation. The ideas and conclusions expressed here are solely my own, they may be superseded by additional news disclosures, and they are not meant in any way to reflect upon the current or future practices of the U.S. Navy.

Technically, since the vessel impacted terrain, she is considered to have “run aground.” To laymen, that phrase might give the wrong impression of what seems to have happened. The terrain with which San Francisco collided may have been a seamount -- an extinct undersea volcano -- which did not show on any of her navigational charts. (The world’s oceans are peppered with countless seamounts.) It is also possible that recent earthquake activity altered seafloor contours, and this fact was not realized in advance. (As the horrific earthquake and tsunami in the eastern Indian Ocean demonstrate, such events can indeed take place.) Another scenario is that a mountain arose where one had not existed before, as a result of ongoing volcanic activity.

So we need to understand a little about nautical charts, seafloor geology, and regular submarine “work habits.”

Nautical charts: The world’s oceans have a total surface area of tens of millions of square miles. In the era since modern oceanography began, and nations started deploying civilian or military oceanographic research ships, it has simply been impossible to map much of the seafloor in very exacting detail. Certain areas, of particular interest to countries such as the U.S. or former USSR, have been charted very thoroughly to support submarine maneuvers -- and anti-submarine warfare, too. But those regions represent only a portion of the total planetwide seabed, and they tend to be concentrated in geographic locations that were most relevant during the Cold War. After the Soviet Union collapsed, military oceanographic research has been scaled back drastically, due to budget cuts. In some cases, in some areas, the only charts available for United States Navy warships are rather old, and were inaccurate or incomplete even when first prepared.

Furthermore, accuracy is relative, and time-sensitive. Charts more than adequate for some purposes, such as commercial continental-shelf oil and natural gas exploration, are not fine enough for other purposes, including military activity (both real or training exercises) in coastal or shallow (“littoral”) waters. Accuracy is time-dependent because the precise arrangement of the seabed isn’t forever fixed and unchanging, as was once believed.

Seafloor geology: The ocean floor in many locations is extremely active in geological terms. Even today, the phenomena that occur, and their precise causal mechanisms, are not all well understood. For instance, the first “black smoker” hydrothermal vents weren’t discovered until the 1970s: Before a research minisub encountered one eye-to-eye, scientists never even suspected that such things might exist. Yet in the past three decades, many hundreds of gigantic fields of black smokers (and “white smokers” too, caused by different chemistry) have been found all over the world.

Undersea volcanoes, both extinct and active, can develop a structure quite different from volcanoes occurring on land. Because the lava outflows hit cold seawater at high pressure, the lava solidifies very rapidly. Instead of the familiar cone-shaped or terraced shield-shaped volcanoes that arise in the open air, volcanoes under the sea often tend to pile up much more like sharp pinnacles -- their sides can be nearly vertical, projecting literally miles above the surrounding deep-ocean basin’s floor. Oceanic volcanoes sometimes happen in chains, apparently because a permanent hot-spot in the earth’s mantle periodically causes magma eruptions through an overlying, gradually moving tectonic plate. Other volcanoes occur at the margins between two adjacent plates, when they either press together and one slides under the other, or they spread apart, and lava emerges from the resulting gap for eons to create long mid-ocean ridges.

Seamount tips may or may not project above the surface. If a chain of them do stick out of the water, you get something like the Hawaiian Islands -- or the Carolines. Parts of the Pacific are particularly active volcanically, because that ocean is rimmed by the famous “Ring of Fire.” In fact, a new island is being born in Hawaii right now, as a live volcano on the seafloor near Big Island gradually builds itself higher and higher. To give an idea of the steepness involved, the waters just a few miles off Oahu reach a depth of more than 15,000 feet.

As another example, just a few years ago a nuclear submarine performing investigations under the North Pole ice cap discovered an area of large lava outflows only a few months old, where no such outflows were believed to be possible. The position of these fresh lava deposits subsequently was found to correlate exactly with a series of minor undersea seismic events that had been detected by instruments on land. Earthquakes of varying Richter Scale magnitudes are going on all the time underwater; they don’t always cause tsunamis, or provide recognizable signatures that the seafloor terrain has changed.

Submarine procedures: For any naval submarine, stealth is always of the utmost importance. Remaining undetected by an adversary can make the difference between victory and defeat in a sub-on-sub dogfight, and between destruction and survivability during a shooting war. The best way to hold a decisive advantage in stealth is to practice it constantly. Submariners therefore frequently conduct simulated wartime operations, to maintain various otherwise-perishable crew skills. Also -- vital to national defense and homeland security -- they do this to maximize the credibility of the deterrent represented by both nuclear missile “boomers” (SSBNs), and conventionally armed fast-attacks (SSNs). Thus, whereas cruising around and pinging on sonar constantly to see if there’s an unexpected terrain feature dead ahead might appear to be a good safety measure, in reality, given the bigger picture of why submarines exist and what they’re for, active pinging is avoided whenever possible, in favor of highly sophisticated passive (listening-only) systems.

Furthermore, the effectiveness of all sonar systems degrades as a submarine goes faster through the water. This is because hydrodynamic drag, and the ship’s own propulsion machinery, create noise that deafens the sonar receptors, called hydrophones. It has always been an inescapable and challenging tradeoff for submarine officers to make, balancing between speed of reaching a crisis destination (or outrunning an inbound torpedo), and sensitivity of the hydrophone arrays. There’s nothing easy about commanding, or serving on, an SSN or an SSBN.

Conclusion: We ought to mourn the crewman who perished, pray that the other seriously injured make good recoveries, and give thanks that USS San Francisco reached port for needed repairs. Should submarine crews be provided with seatbelts? Only a few watch stations typically are equipped with them now. Sleeping racks have straps to hold crewmen in, when near the surface during very rough seas, but ordinarily these straps aren’t used. Besides, many watch stations, and other essential duties, require standing, not sitting, for hours at a time. Are crash helmets -- and even safety harnesses -- worth considering, at least for use when the sub is making high speed?

Is increased funding appropriate to better map the ocean floor in areas now more relevant than they once were, given the Global War on Terror and Third World nuclear weapons proliferation? Do submarine squadron- and group-level routing guidelines, and underway navigation techniques, need critical revisiting? I’m sure that as the Navy continues their investigations, these issues will be given proper attention. One thing the Silent Service is very good at is learning well from hard experience.

JoeBuff.Com / Joe Buff Inc. Joe Buff, President Dutchess County, New York E-Mail readermail@JoeBuff.Com