ASI, the Boston AI startup formerly known as Air Space Intelligence, raised $325 million in a Spark Capital–led Series C valuing it at $3 billion, on the strength of software that models air traffic, power grids and military operations so operators can act before problems spread. It holds an $875 million, 12-year Federal Aviation Administration contract to manage US air traffic, began use around Washington in September, and also counts the US Army, Delta, Alaska, United, National Grid and Joby among its customers, with the FAA planning to expand the system nationwide.