The Helikopter-Streichquartett (English: 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 1995. Although performable as a self-sufficient piece, it also forms the third scene of the opera Mittwoch aus Licht ("Wednesday from Light").
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). By this time, he had had several more dreams concerning the piece, including one involving a swarm of bees and a violinist, about which Stockhausen said, “The buzzing made by lots of bees is a magic sound to me” (Schweitzer 2008). 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. In part because of protests by the Austrian Green Party, that it would be "absolutely impossible for Austrian air to be polluted by performing this Stockhausen", in the end the planned 1994 première had to be cancelled (Stockhausen 2004, 90).
The first performances of the piece took place in Amsterdam on 26 June 1995, as part of the Holland Festival, with Alouette helicopters from the Royal Dutch Air Force display team, The Grasshoppers. The performers were: first violinist Irvine Arditti and pilot Marco Oliver; second violinist Graeme Jennings and pilot Lieutenant Denis Jans; violist Garth Knox and pilot Lieutenant Robert de Lange; cellist Rohan de Saram and pilot Captain Erik Boekelman (Stockhausen 1996, 216). There were three performances given, at the Westergasfabriek, after two test flights at the same location the day before, and several earlier at an airfield in Deelen for the purpose of trying out the microphones (Stockhausen 2004, 90). Following these performances, Stockhausen revised the score, adding about three minutes of material near the end, just before the descent, increasing the overall duration from about 29 minutes to 32 minutes (Stockhausen 2004, 91). Since its premiere, the Helicopter Quartet has been performed "fairly regularly" and has become "the most iconic piece of classical music from the 1990s", though it was not presented in its full context, as the second scene of Mittwoch aus Licht, until the opera's staged premiere in August 2012 (Fallows 2012, 1284).
The Licht cycle—as a whole and in all of its parts—is serially composed, being based upon a three-layered "superformula". This design principle is an extension of the series-based techniques Stockhausen developed at the beginning of the 1950s—a connection to which Stockhausen himself has repeatedly called attention in his theoretical explanations (Misch 2004, 36). The Quartet is based on a short portion of the Eve layer from the Wednesday segment of the superformula: D–F–G♭. After the initial ascent, there are three iterations of the three-voiced superformula, each time distributed among the four instruments, and each time with the Michael, Eve, and Lucifer lines in a different vertical arrangement. The superformula as a whole is successively transposed so that the Eve layer begins each time with the corresponding pitch from the "helicopter" segment: D–F–G♭ (Shimizu 2004, 66). The durations of the three statements of the triple formula are also determined by the rhythms of the small "helicopter" segment (Stockhausen 2004, 98).
More general traits found in the work are also characteristic of the serial fabric of Stockhausen's music. For example, the interpenetration of macro and micro dimensions, found in earlier compositions such as Kontakte, where Stockhausen compresses rhythm into pitch, or in Hymnen, where he slows down the sound of geese until they are revealed as the shouts of a football crowd. The violin tremolos here and also in Mittwoch's preceding scene, Orchester-Finalisten, invoke the sound of a buzzing mosquito, so "what the composer is also saying is that the mosquito is also a tiny helicopter", and the connection between the two is being made by the violin (Maconie 2005, 514). Another is the way in which the scenic character of the Helicopter Quartet forms one of four "serial variants": The first and fourth scenes of the opera represent the idea of communication and cooperation, first when World Parliamentarians meet to debate the topic of love, and then when interplanetary delegates consider cosmic problems, while the second scene and this one revolve around the idea of community music making (Misch 2004, 42–43).
A third serial principle is the integration of distinct elements into a whole. This was expressed by Stockhausen in a text written in 1953:
Evidently, self-contemplation and the awareness of a universal, planned order exist today "more than ever”. With this comes the desire to give the individual tone a very specific sense that transcends momentary saturation and the merely impulsive play of organization and combination; a sense, that is, of music as a representation of that comprehensive "global" structure in which everything is integrated. (Stockhausen 1963, 46)
In Licht generally this is seen in "scenic contexts that are not tied to a single, linear, teleological narrative, but as the compositional events in multi-dimensional, process-independent, run in folding, intersecting, or parallel layers and yet are held together by the principle of uniformity" (Misch 2004, 42). In the Helicopter Quartet in particular this is manifested spatially, as the physical separation of the players from the audience and among themselves, circling in the sky in four different helicopters, is overcome through the use of audio-visual equipment, so that "only when transmitted via television screens and loudspeakers in the concert hall do the four-layered musical events fit together into a unified whole" (Misch 2004, 43).
Performance practice 
A performance requires: four helicopters, each equipped with a pilot and sound technician, television transmitter and 3-channel sound transmitter, and an auditorium with four columns of televisions and loudspeakers, a sound projectionist with mixing desk, and a moderator (optional), as well as the members of the string quartet.
The piece focuses on Stockhausen's dreamed idea of a string quartet playing tremolos which blend so well with the timbres and the rhythms of the rotor blades that the helicopters sound like musical instruments (Stockhausen 1996, 214). This is accomplished by using microphones placed so the helicopters may blend with the stringed instruments, with the instruments being heard as slightly louder than the blades (Stockhausen 1996, 215).
The piece is played as follows: A moderator, who may be the sound projectionist, introduces the quartet, and then explains the technical aspects of the piece. The players then walk out, always being visible to the auditorium audience via the video cameras that follow them, until they have all arrived at and boarded their helicopters (Stockhausen 1996, 214–15).
From the moment of takeoff until disembarcation the musicians and helicopters remain constantly in the view of the cameras, with video and audio (using three microphones in each helicopter) of each string player transmitted to his assigned group of television monitors in the auditorium. "The earth can be seen through the glass cockpit of the helicopter behind each player" (Stockhausen 1996, 215).
Then the piece begins. The helicopters circle at a radius of 6 km from the auditorium, changing altitude constantly to create the 'bounce' of the piece. All 12 incoming signals are controlled by the sound crew (Stockhausen 2012, 36, 82).
The descent lasts five minutes, with the decreasing sound of the rotor blades acting as a background as the quartet re-enter the hall. The moderator then takes questions and leads applause (Stockhausen 2012, 36, 39, 82, 84).
Press reviews 
Writing for the New York Times, Alex Ross called the premiere a "memorable spectacle" citing the virtuoso performances by both the Arditti and the Grasshoppers. However, his review was mostly negative:
German experimentalism in its classic form has evidently run its course. Nothing illustrated its obsolescence more lucidly than the recent premiere at the Holland Festival of a Helicopter String Quartet by Karlheinz Stockhausen...it was not, as Mr. Stockhausen claimed, important research into new sound materials, nor anything of consequence in purely musical terms. It was a grandiose absurdist entertainment, not unlike Christo's wrapping of the Reichstag back in Berlin. (Ross 1995)
Andrew Clements in The Guardian marveled at Stockhausen's logistical achievement:
The technological complexities of making such a thing work almost flawlessly are immense (a planned performance in Salzburg last year failed, literally and metaphorically, to get off the ground), and in the context of Stockhausen's achievement as a composer the Helicopter Quartet may not be hugely significant, but as a reminder of the sheer force of his creative personality and organisational ability it is a remarkable if impossibly bizarre achievement. And what it all has to do with the opera only time will reveal. (Clements 1995)
Helikopter-Streichquartett says things about quartet psychology the placing of oneself at risk, the trust that others will come in on time (isolated visually and aurally, the players could get directions only from a click-track heard on headphones) and the devotion to duty...this is a work that can be just as well imagined as experienced. Indeed, the Helikopter-Streichquartett of the imagination is probably to be preferred, since the one big disappointment of the Amsterdam performance was that one had so little sense of the musicians the Arditti Quartet being up aloft: the monitors just showed us four guys in cramped conditions, bowing away. (Griffiths 1995)
Marlise Simons, writing in The New York Times, provides a snapshot of multiple critical reactions in the Dutch press:
The performance was widely reviewed in Dutch newspapers, which admired the flawless technical delivery but had less ear for the unusual sounds. The influential NRC-Handelsblad found "the hot-tempered music" from clattering aircraft disturbing and said the "noise of the rotorblades created tension" in the audience. But Yannis Anninos, a Greek composer who had flown from Athens to attend the concert, said the Helicopter Quartet was the "superb work of a genius." Mr. Stockhausen said he had other performances in mind for the quartet. He was also asked if he thought it possible to raise an entire orchestra aloft in helicopters. "Why not?" he said. (Simons 1995)
The CD 
The first CD was created on request of the Arditti Quartet themselves, and includes both the world-première recording and a studio recording of a revised version, which adds some material composed after the world première. The studio recording was made by the WDR, on 7 December 1996 in Kürten, using the Übertragungswagen, or mobile studio. They used four different rooms in the studio, with the helicopter sounds dubbed in, using Sony 24-track tape.
- Stockhausen, Karlheinz. Helikopter-Streichquartett: Uraufführung 1995 + Studioproduktion 1996. Arditti String Quartet (Irvine Arditti, Graeme Jennings [world premiere] and David Alberman [studio recording of the revised score], violins; Garth Knox, viola; Rohan de Saram, cello); "The Grasshoppers" (helicopter acrobatic team); Karlheinz Stockhausen, musical direction, recording supervision, sound projection, mix-down, and moderation [of the world premiere]. Stockhausen Complete Edition, Compact Disc 53 A-B (2 CDs). Kürten: Stockhausen-Verlag, 1999. Studio version also released on Montaigne Auvidis MO 782097 (CD).
- Stockhausen, Karlheinz. Helikopter-Streichquartett. Arditti String Quartet (Irvine Arditti & David Alberman, violins; Garth Knox, viola; Rohan de Saram, cello); "The Grasshoppers" (helicopter acrobatic team, recording from the third Amsterdam performance, mixed in). Arditti Quartet Edition 35. Montaigne Auvidis MO 782097 (single CD). 32'00". Paris: Montaigne Auvidis, 1999.
- Helicopter String Quartet, a film by Frank Scheffer. Close-up: documentaireserie waarin Frank Scheffer zijn visie geeft op diverse 20e-eeuwse componisten. [S.l.]: AVRO. Televisie-opname, 1995.
- German DVD release (German and English, DVD) Helicopter String Quartet. Frank Scheffer; Karlheinz Stockhausen. Kürten, Germany: Stockhausen-Verlag, 2006.
- UK release: Helicopter String Quartet. Frank Scheffer; Ton van der Lee; Karlheinz Stockhausen. German. Videorecording: DVD video 1 videodisc (77 min.). London: 2008.
- French DVD release. Helicopter String Quartet. Karlheinz Stockhausen; Frank Scheffer. Videorecording: DVD video (77 mins. [erroneously listed as 113 min. in publisher's catalogue]). [Paris]: Idéale Audience International, 2008.
- Stockhausen: Helikopter Streichquartett. Sound Director: André Richard. a co-production with Red Bull & Salzburg Festival. Bernhard Fleischer Moving Images, 2003.
- Boehmer, Konrad. 1998. "Ab in die Wolken mit Knattern …". Neue Zeitschrift für Musik 159, no. 4 (July–August):43–47.
- Clements, Andrew. 1995. "Super Soaraway Stockhausen". The Guardian (June 29).
- Dirmeikis, Paul. 1999. Le Souffle du temps: Quodlibet pour Karlheinz Stockhausen. [La Seyne-sur-Mer]: Éditions Telo Martius. ISBN 2-905023-37-6.
- Fallows, David. 2012. "Mittwoch aus Licht: Birmingham Opera Company at the Argyle Works, Birmingham, August 22". Opera (October): 1284–86.
- Griffiths, Paul. 1995. "Stockhausen Has Lift-Off". The Times (July 5).
- Maconie, Robin. 2005. Other Planets: The Music of Karlheinz Stockhausen. Lanham, Maryland, Toronto, Oxford: The Scarecrow Press, Inc. ISBN 0-8108-5356-6.
- Misch, Imke. 2004. "Serielles Denken in LICHT.” In Internationales Stockhausen-Symposion 2000: LICHT. Musikwissenschaftliches Institut der Universität zu Köln, 19. bis 22. Oktober 2000. Tagungsbericht. Edited by Imke Misch and Christoph von Blumröder, 36–51. Münster, Berlin, London: LIT-Verlag.
- Ross, Alex. 1995. "CLASSICAL VIEW; In Flux, Berlin Remaps, Reminds", New York Times (August 13).
- Schweitzer, Vivien. 2008. "Fulfilling a Dream With Strings and Rotors". New York Times (13 July).
- Shimizu, Minoru. 2004. “Potentiale multimedialer Aufführung und 'szenische Musik'—einige Bemerkungen zum Helikopter-Streichquartett.” In Internationales Stockhausen-Symposion 2000: LICHT. Musikwissenschaftliches Institut der Universität zu Köln, 19. bis 22. Oktober 2000. Tagungsbericht. Edited by Imke Misch and Christoph von Blumröder, 61–73. Münster, Berlin, London: LIT-Verlag.
- Simons, Marlise. 1995. "A Helicopter Quartet. What Else?". New York Times (July 31).
- Spahn, Claus. 2007. "Abheben in Braunschweig". Die Zeit, no. 26 (21 June): 50.
- Stockhausen, Karlheinz. 1963. "Zur Situation des Metiers (Klangkomposition)”. In his Texte zur Musik 1, edited and with an afterword by Dieter Schnebel, 45–61. DuMont Dokumente. Cologne: Verlag M. DuMont Schauberg.
- Stockhausen, Karlheinz. 1996. "Helikopter-Streichquartett". Grand Street 14, no. 4 (Spring, "Grand Street 56: Dreams"): 213–25. ISBN 1-885490-07-0. Online variant version , as "Introduction: HELICOPTER STRING QUARTET (1992/93)" (some omissions, some supplements, different illustrations).
- Stockhausen, Karlheinz. 1999. Helikopter-Streichquartett, booklet for the Stockhausen Complete Edition CD 53.
- Stockhausen, Karlheinz. 2004. “Helikopter-Streichquartett: Eine 8-Spur-Tonbandaufführung mit Erläuterungen.” In Internationales Stockhausen-Symposion 2000: LICHT. Musikwissenschaftliches Institut der Universität zu Köln, 19. bis 22. Oktober 2000. Tagungsbericht. Edited by Imke Misch and Christoph von Blumröder, 89–114. Münster, Berlin, London: LIT-Verlag.
- Stockhausen, Karlheinz. 2012. "Helikopter-Streichquartett (1992/93): Dritte Szene vom Mittwoch aus Licht" / Helicopter String Quartet (1992/93): Third Scene of of [sic] Wednesday from Light". In Karlheinz Stockhausen, Mittwoch aus Licht: Uraufführung, Birmingham Opera Company: London 2012 Festival, 35–40, 81–84. Kürten: Stockhausen-Stiftung für Musik.
- Toop, Richard. 2008. "Mittwoch aus Licht ('Wednesday from Light')". Grove Music Online: The New Grove Dictionary of Opera (22 October) (Subscription access) (Accessed 17 April 2013).
Further reading 
- Arditti, Irvine. 2008. "German Focus: Flight of Fantasy". The Strad 119, no. 1415 (March): 52–53, 55.
- Stockhausen Official Site
- Helicopter String Quartet photos
- "Stockhausen: Watch the Helicopter String Quartet". Video of the Elysian Quartet at the Birmingham Opera production, 2012. Thespace.org (Accessed 21 April 2012). [Note: Video does not work in Google Chrome]
- Geyer, Elke. 2009. "Stockhausens Helikopter-Streichquartett: Ein aufwendiges Werk für vier Hubschrauber, Musiker und Techniker" (record review). Suite101.de: Das Netzwerk der Autoren (3 October). (German)
- Maconie, Robin. "Helikopter-Streichquartett" (English)
- Maconie, Robin. 2005. "Stockhausen's Musical Helicopters" (English)