Stockhausen's helicopter opera set for take off

With a string quartet flying in helicopters, musicians suspended on giant swings and a dancing camel, Karlheinz Stockhausen's radical six-hour opera Mittwoch Aus Licht was thought to be unstageable - until now.

There are four helicopters lined up on a disused patch of tarmac just outside Birmingham city centre, and the members of the Elysian string quartet are cautiously trying out their unconventional concert spaces for the first time.

With a helicopter each, they are squeezed into their cabins, with music stands in front of them, camera rigs next to them and banks of broadcasting kit at the side, ready to beam their airborne performances back to the ground.

It is just five days before their public premiere, when they will attempt to synchronise their playing while circling high above the city, as 500 audience members watch and listen on four big screens in a disused factory somewhere down below.

They have rehearsed on the ground, but now they are looking a little nervous.

"The thing we haven't done yet is play the music with the massive loud noise of the helicopter at the same time, so that will be a challenge," says Jennymay Logan. "And also be on a vibrating surface, and play the violin at the same time, and read music, and not be sick."

This fleet of helicopters will become a regular sight in the skies over the city in the next couple of weeks, forming part of an ambitious opera by the experimental and highly influential composer Karlheinz Stockhausen, whose ideas were inspirational to some, and ridiculous to others.

Opera companies in Bonn, Berne, Basel and Bregenz have previously tried to stage Mittwoch Aus Licht in full. All have failed. Now, it is Birmingham's turn.

"The fact that it's never been done was very attractive," says Birmingham Opera Company artistic director Graham Vick. "But I love the music, I really do, and I wanted to do this music with this company."

There is a cast of 200, including 11 orchestral musicians suspended on giant swings, being gently lowered and raised from the ceiling of the old chemical factory that is being used as a venue; two choirs, one of which will be perched atop a forest of 40 giant chairs; a trombonist in a paddling pool trying to sound like an elephant; and the dancing camel (not a real one).

The audience will spend the six hours sitting on the factory floor and walking between areas of the building, with long sections performed in the dark.

Does Vick ever think he is in the middle of one big practical joke?

"Unquestionably there's an enormous amount of humour," he replies. "And, yes, on one level there's a laughter. But do you know, the Orientals think that laughter is God, don't they?"

Mittwoch Aus Licht (Wednesday From Light) is one part of Stockhausen's epic Licht cycle, written between 1977 and 2003. The idea for the helicopter segment, which lasts for 15 minutes, came to him in a dream after he was commissioned to write a string quartet in 1994.

"Stockhausen said: 'I'll never write a string quartet in my whole life,'" explains Kathinka Pasveer, who worked closely with Stockhausen and is the music director for this production. "He never used traditional forms - he never wrote symphonies or concertos.

"But then after he had refused this commission, he had this dream of four helicopters with four string players in it. When we went the next day into the studio, suddenly he saw four helicopters flying by the window."

He was articulate beyond belief, fertile, with a mercurial, wicked sense of humour and limitless imagination”

He decided that was a sign from above, and so put the trifling matter of technical requirements to one side and went ahead with his vision of musicians in the skies.

"Stockhausen loved this sound of rotor blades because for him it's music - the different rhythms, the different pitches," Pasveer adds.

The members of the string quartet will not be able to hear each other, but will wear headphones through which they will be fed clicks to keep them in time as well as the voice of Stockhausen's son Simon, counting which bars they should be playing.

Graham Vick, who has staged work in venues from La Scala to the Royal Opera House, once worked with Stockhausen for five days and describes the composer as "a dazzlingly brilliant man".

"He was articulate beyond belief, fertile, with a mercurial, wicked sense of humour and limitless imagination," Vick says.

Enthusiasts are due to travel from around the world for the four performances, and Birmingham is hoping to succeed where others failed thanks to funding from Arts Council England as part of the London 2012 Festival, as well as from Birmingham City Council.

Vick will not confirm the reported budget of £1m, only saying it cost "a lot of money". So why is it worth it, especially at a time of cuts?

"Because it's a great work of genius that's never been done" Vick replies.

"Because it's celebratory and will bring a huge amount of attention to the company. Because all of the people involved will be stimulated creatively beyond anything they've experienced before, as will the audience, and they will take that away with them."

Back on the tarmac, in his helicopter, viola player Vincent Sipprell is reflecting on the rigorous rehearsals they have been put through on the ground by Pasveer.

"If we make one slight mistake, she knows," he says. "But once you're in the helicopter I think it's going to be a bit of a free for all. We'll just try to survive it."

Mittwoch Aus Licht opens on Wednesday 22 August. It will also be broadcast on digital arts channel The Space.