Maritime reconnaissance

Maritime reconnaissance equip with sensors,...

Sensors

P-3 Orion clearly showing the MAD (tail boom) and sonobuoy chutes (array of dark spots under rear fuselage) while the IR sensor is retracted and not visible.
Maritime patrol aircraft are typically fitted with a wide range of sensors:[1]

Radar to detect surface shipping movements. Radar can also detect a submarine snorkel or periscope, and the wake it creates.
Magnetic anomaly detector (MAD) to detect the iron in a submarine's hull. The MAD sensor is typically mounted on an extension from the tail or is trailed behind the aircraft on a cable to minimize interference from the metal in the rest of the aircraft;
Sonobuoys self-contained sonar transmitter/receivers dropped into the water to transmit data back to the aircraft for analysis;
ELINT sensors to monitor communications and radar emissions;
Infrared cameras for detecting exhaust streams and other sources of heat and are useful in monitoring shipping movements and fishing activity.
Visual inspection using the aircrew's eyes, in some cases aided by searchlights or flares.
A modern military maritime patrol aircraft typically carries a dozen or so crew members, including relief flight crews, to effectively operate the equipment for 12 hours or more at a time.[2]