The Société Nationale des Constructions Aéronautiques du Sud-Est (SNCASE, or simply Sud-Est) was a French aircraft manufacturer. It was born from the nationalisation of the French aeronautical industries in 1937.

They produced 2 autogyros, C.34 and the SE.700 Alouette (skylark). After World War II SNCASE continued experimenting with helicopters with the help from a team from Focke Achgelis. They built the SE.3000 which was a French version of the twin-rotor Focke-Achgelis FA 223 and a smaller SE.3101, built around the Focke-Wulf Fw 61. With this experience SNCASE went on to design more helicopters: SE.3100, SE.3110 and eventually the SE.3120 Alouette.

The Alouette first flew on July 21 1951 and broke the helicopter distance and speed records in July 1953. A production for several hundreds was envisaged but hopes were soon dashed when the SE.3120 was found non-marketable because it was too complicated.