Editing Magnetic anomaly detector (section)

{{Short description|Instrument for detecting variations in the Earth's magnetic field}}
[[File:Lockheed P-3C (JMSDF)02.jpg|thumb|MAD rear boom on [[P-3C]]]]
[[File:SH-60B Seahawk.jpg|thumb|The [[SH-60B Seahawk]] helicopter carries a yellow and red towed MAD array known as a "MAD bird", seen on the aft fuselage]]

A '''magnetic anomaly detector''' ('''MAD''') is an instrument used to detect minute variations in the [[Earth's magnetic field]].<ref>{{cite book |title=A Dictionary of Aviation |first=David W. |last=Wragg |isbn=9780850451634 |edition=first |publisher=Osprey |year=1973 |page=183}}</ref> The term typically refers to [[magnetometer]]s used by military forces to detect [[submarine]]s (a mass of [[ferromagnetic]] material creates a detectable disturbance in the [[magnetic field]]). Military MAD equipment is a descendant of [[geomagnetic]] [[geological survey|survey]] or [[aeromagnetic survey]] instruments used to search for [[mineral]]s by detecting their disturbance of the normal earth-field.