In 1965 Gerhard Waibel left the Technical University of Darmstadt to enter Alexander Schleicher GmbH & Co as a designer.

The exploits of Hans-Werner Grosse in an ASW 12 are legendary, e.g. the 1,461 km flight of April 25, 1972 from Lübeck to Biarritz which stood for thirty years as the absolute World Free Distance Record.

The wings were of fiberglass/balsa wood sandwich construction and were built in the traditional manner using negative molds.

For approach and landing control the ASW 12 possessed a braking parachute rather than traditional spoilers or airbrakes.

The system proved unreliable and a number of ASW 12 were retrofitted with a second parachute to reduce the risk of an unsuccessful landing.