Days-At-Sea (DAS) is the unit used to annually plan mission time aboard NOAA ships. Approximately 100 survey and research missions are planned and executed each year. A DAS is a day is which the ship is underway, under its own power, for greater than one hour, conducting mission operations, training, sea trials, or calibration. Also included are days in which hydrographic ships are not underway but are conducting operations aboard one or more ship-based launches.