Last week, when the U.S. Coast Guard called off its search for three men, including two NFL football players, who were pitched into the Gulf of Mexico when their fishing boat capsized, its spokesman commented, "We’re extremely confident that if there are any survivors on the surface of the water that we would have found them."
Following up on this, Scientific American interviewed an oceanographer in the Coast Guard’s Office Search and Rescue, to ask about the source of this confidence. It turns out that the Coast Guard uses Monte Carlo software to plan every search operation. It’s the basis of the system they call SAROPS (Search and Rescue Optimal Planning System). What SAROPS simulates is the drift trajectory for search targets–people, vessels. Based on historical data on drift patterns for similar objects, it projects drift scenarios for various starting locations and times. At the same time, it factors in an environmental risk analysis of wind and current.
The models produce tightly defined options for search patterns, which save search time and increase the likelihood of finding castaways while they are still alive. But, as the Coast Guard oceanographer pointed out about the case of the missing fishermen, "There’s always uncertainty, of course, which is why we’re having a search in the first place."