page_title: Geophysical MASINT
section_title: Airborne dipping sonar
hierarchical_section_title: Geophysical MASINT / Acoustic MASINT / Active acoustic sensors and supporting measurements / Airborne dipping sonar
caption_attribution_description: An AQS-13 DIPPING SONAR being lowered from an SH-3H Sea King helicopter from Helicopter Anti-submarine Squadron 2 (HS-2).
context_page_description: Geophysical MASINT is a branch of Measurement and Signature Intelligence that involves phenomena transmitted through the earth and manmade structures including emitted or reflected sounds, pressure waves, vibrations, and magnetic field or ionosphere disturbances.
  According to the United States Department of Defense, MASINT is technically derived intelligence that – when collected, processed, and analyzed by dedicated MASINT systems – results in intelligence that detects, tracks, identifies, or describes the signatures of fixed or dynamic target sources. MASINT was recognized as a formal intelligence discipline in 1986. Another way to describe MASINT is a "non-literal" discipline. It feeds on a target's unintended emissive by-products, the "trails" - the spectral, chemical or RF that an object leaves behind. These trails form distinct signatures, which can be exploited as reliable discriminators to characterize specific events or disclose hidden targets."
context_section_description: Antisubmarine helicopters can carry a "dipping" sonar head at the end of a cable, which the helicopter can raise from or lower into the water. The helicopter would typically dip the sonar when trying to localize a target submarine, usually in cooperation with other ASW platforms or with sonobuoys. Typically, the helicopter would raise the head after dropping an ASW weapon, to avoid damaging the sensitive receiver. Not all variants of the same basic helicopter, even assigned to ASW, carry dipping sonar; some may trade the weight of the sonar for more sonobuoy or weapon capacity.
  The EH101 helicopter, used by a number of nations, has a variety of dipping sonars. The (British) Royal Navy version has Ferranti/Thomson-CSF (now Thales) sonar, while the Italian version uses the HELRAS. Russian Ka-25 helicopters carry dipping sonar, as does the US  LAMPS, US MH-60R helicopter, which carries the Thales AQS-22 dipping sonar. The older SH-60F helicopter carries the AQS-13F dipping sonar.
caption: AN/AQS-13 Dipping sonar deployed from an H-3 Sea King, an aircraft used by numerous countries and produced in Italy, Japan, and the United Kingdom
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