The Helikopter-Streichquartett (Helicopter String Quartet) is one of Karlheinz Stockhausen's best-known pieces, and one of the most complex to perform. It involves a string quartet, four helicopters with pilots, as well as audio and video equipment and technicians. It was first performed and recorded in 1996. Although performable as a self-sufficient piece, it also forms the third scene of the opera Mittwoch aus Licht ("Wednesday from Licht"). The Helicopter Quartet was originally commissioned by Professor Hans Landesmann of the Salzburger Festspiele in early 1991 (Stockhausen 1996, 214). Stockhausen's initial reaction was that he was not interested in writing a string quartet, but then one night he dreamed he was flying above four helicopters, each carrying a member of a string quartet; he could see into and through the transparent helicopters (Dirmeikis 1999, 21–22). He subsequently made some sketches and plans, but it was not until 1992–93 that he found the time to compose the quartet (Stockhausen 1996,214). The Arditti Quartet was to play the première. After Stockhausen finished his score, it was sent back to Professor Landesmann for criticism. His reaction was positive, as was that of the Director of the Festspiele, Gerard Mortier. A long series of negotiations started with the Festspiele and the Austrian army, who were to loan the helicopters, as well as various TV channels who were airing the piece. But in the end the planned 1994 première had to be cancelled. The first performance of the piece took place in Amsterdam on June 26, 1995, as part of the Holland Festival.