Welcome to Naval Warfare enthusiast website by PMC.
Anti-submarine warfare (ASW, or in the older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are typically carried out to protect friendly shipping and coastal facilities from submarine attacks and to overcome blockades. -source Anti-submarine warfare wikipedia.
Simple ASW scenario is a surface ship launching a helicopter with sonobuoys and dipping sonar.
ASW platforms also include Maritime Patrol Aircraft (MPA) like P-3C Orion which is a turboprop aircraft being able to travel great distances, loiter a long time and deploy a lot of sonobuoys.