Australia has started dropping sonobuoys as part of its hunt for the black box beacon in the Indian Ocean.
The Lockheed P-3 Orion is a four-engine turboprop anti-submarine and maritime surveillance aircraft developed for the United States Navy and introduced in the 1960s. Lockheed based it on the L-188 Electra commercial airliner. The aircraft is easily recognizable from the Electra by its distinctive tail stinger or "MAD Boom", used for the magnetic detection of submarines.
Over the years, the aircraft has seen numerous design advancements, most notably to its electronics packages. The P-3 Orion is still in use by numerous navies and air forces around the world, primarily for maritime patrol, reconnaissance, anti-surface warfare and anti-submarine warfare. A total of 734 P-3s have been built, and during 2012, it joined the handful of military aircraft including the Boeing B-52 Stratofortress and Boeing KC-135 Stratotanker that have served 50 years of continuous use by the United States military. The U.S. Navy's remaining P-3C aircraft will eventually be replaced by the P-8A Poseidon.