Editing Magnetic anomaly detector (section)

==Operation==
[[File:Tu-142M&P-3C-Orion-1986-DN-SC-87-00265.jpg|thumb|A Soviet [[Tupolev Tu-142|Tu-142MK]] (with MAD located in aft-facing fin-top fairing) escorted by US Navy [[Lockheed P-3C]] (MAD located in projection at base of tail), March 1986]]
The [[magnetic anomaly]] from a submarine is usually very small. One source estimates that it is only about 0.2 n[[Tesla (unit)|T]] at a distance of 600 m.<ref>{{cite journal|title=Magnetic Anomaly Detection Based on Full Connected Neural Network|year=2019 |page=182198|publisher=[[IEEE]]|doi=10.1109/ACCESS.2019.2943544|last1=Liu |first1=Shuchang |last2=Hu |first2=Jiafei |last3=Li |first3=Peisen |last4=Wan |first4=Chengbiao |last5=Chen |first5=Zhuo |last6=Pan |first6=Mengchun |last7=Zhang |first7=Qi |last8=Liu |first8=Zhongyan |last9=Wang |first9=Siwei |last10=Chen |first10=Dixiang |last11=Hu |first11=Jingtao |last12=Pan |first12=Xue |journal=IEEE Access |volume=7 |bibcode=2019IEEEA...7r2198L |s2cid=204082945 |doi-access=free }}</ref> Another source estimates that a 100{{nnbsp}}m long and 10 m wide submarine would produce a magnetic flux of 13.33 nT at 500{{nnbsp}}m, 1.65 nT at 1{{nnbsp}}km and 0.01 nT at 5{{nnbsp}}km.<ref>{{cite conference
  |title=Methods of Differential Submarine Detection Based on Magnetic Anomaly and Technology of Probes Arrangement
  |url=https://www.atlantis-press.com/proceedings/iwmecs-15/25840634
  |page=446
  |work=Proceedings of the 2015 2nd International Workshop on Materials Engineering and Computer Sciences
  |author1=Yuqin Chen |author2=Jiansheng Yuan
  |year=2015
  |doi=10.2991/iwmecs-15.2015.88
|doi-access=free
  }}</ref> To reduce interference from electrical equipment or metal in the [[fuselage]] of the aircraft, the MAD sensor is placed at the end of a boom or on a towed aerodynamic device.<ref name=":0">{{Cite web|url=https://fas.org/man/dod-101/navy/docs/fun/part09.htm|title=Fundamentals of Naval Weapons Systems - Chapter 9 Underwater Detection and Tracking Systems}}</ref> Even so, the submarine must be very near the aircraft's position and close to the sea surface for detection of the anomaly, because magnetic fields decrease as the [[Magnet#Fields of a magnet|inverse cube of distance]], one source gives a detection [[slant range]] of 500{{nnbsp}}m.<ref name=":0" /> The size of the submarine, its hull composition and orientation, as well as the water depth and complexity of the natural magnetic field, determine the detection range. MAD devices are usually mounted on [[aircraft]].<ref name=":0" /> For example, one study showed that a horizontal detection range of 450–800{{nnbsp}}m, when aircraft was 200{{nnbsp}}m above a submarine, decreased to less than 150{{nnbsp}}m when the aircraft was 400{{nnbsp}}m above the submarine.<ref name=chengjing>{{cite journal|title=Detection Range of Airborne Magnetometers in Magnetic Anomaly Detection|author=Chengjing Li|journal=Journal of Engineering Science and Technology Review |year=2015 |volume=8 |issue=4 |pages=105–110 |doi=10.25103/JESTR.084.17 |s2cid=117237628 |display-authors=etal|doi-access=free }}</ref>

If the sea floor has sunken ships, then submarines may operate near them to confuse magnetic anomaly detectors.<ref>{{cite book|title=China's Rising Sea Power|page=93-94|author=Peter Howarth}}</ref>

MAD has certain advantages over other detection methods. It is a passive detection method. Unlike sonar it is not impacted by meteorological conditions; indeed above [[sea state]] 5, MAD may be the only reliable method for submarine detection.<ref name=chengjing/>