The Lockheed SP-2H Neptune was a Cold War maritime patrol aircraft designed to detect and combat submarines. It featured a unique combination of piston and jet engines and was equipped with advanced sensors, including radar, sonobuoys, and a magnetic anomaly detector.

The SP-2H was operated not only by the U.S. Navy but also by countries such as the Netherlands, France, Canada, and Australia. In the Netherlands, it remained in service until the early 1980s, flying from the Valkenburg naval airbase.