Missile Impact Location System

The Missile Impact Location System or Missile Impact Locating System (MILS) is an ocean acoustic detection system designed to locate the impact position of test missile nose cones at the ocean's surface and then the position of the cone itself for recovery from the ocean bottom. The systems were installed in the missile test ranges managed by the U.S. Air Force.

Source: Wikipedia — Missile Impact Location System (CC BY-SA 4.0)