The P-3 Orion is based on the ill-fated Lockheed L-188 Electra passenger aircraft. Unlike the unsuccessful Electra, it has repeatedly proven itself in the patrol and anti-submarine role. In 2012, the P-3 will join a tiny handful of aircraft to have enjoyed 50 years of continuous service. However, the celebration will be short lived, as the P-3 is being replaced by the P-8 Poseidon, based on the Boeing 737.