At 18:01, this is the longest song Iron Maiden has ever recorded. "[Bruce Dickinson] was working on ['Empire Of The Clouds'] for about a month on his own," guitarist Adrian Smith recalled to Total Guitar magazine. "Every single day we'd be in the studio blasting out stuff and he'd be in the soundproof glass booth playing piano. Like Beethoven with his ear to the piano, concocting this masterpiece. I think he wrote every single note in it."
"We interpreted it and we did it in sections," Smith continued. "Kevin [Shirley, producer] and Bruce would be in the control room and say, 'That's too bluesy, can you make it a bit more classical sounding?' He recorded all the piano from start to finish and then we played along to that. Then I think they put on all the orchestration afterwards. It's a bit of a story on its own that one."
Lyrically, the song is about the ill-fated British airship, R101, which when built was the world's largest flying craft. It crashed in France on its maiden overseas voyage on October 5, 1930, killing 48 of the 54 passengers on board, a greater toll than the better known Hindenburg tragedy, seven years later.
Dickinson told Classic Rock magazine: "Originally I was going to write a song about World War I and the soldiers who operated the dawn patrols – something a bit atmospheric. Then I went round to Adrian's house and we wrote this song 'Death Or Glory,' which kind of covered that subject in a slightly different way. So I started thinking about the R101."
"I've always been fascinated with airships, and the R101 especially. Only five of the passengers survived when it crashed. I've got a pocket watch of one of the survivors, and a tankard that says: 'Welcome aboard from the airship crew.' To tell that story, I thought, it's a big job – oh, go on then! So I started putting it together piece by piece. It was difficult, because I wanted to get everything as historically and technically accurate, but still making it… poetic, I guess."
Dickinson highlighted drummer Nicko McBrain's contribution to the huge, dramatic climax in the song when the airship crashes. The vocalist said: "He really bought into the story. I told him I wanted all this dissonant stuff for the airship plummeting to earth. I wanted that in the percussion. I said I wanted twisting metal, and he said, 'Oh, you want a bowed gong.' I said, 'What the f--k is that?'"
"He has this big orchestral gong at the back of his kit. You take a violin bow, scrape it against the edge of the gong, and it just resonates. I said, 'That's the sound of the airship dying!' So quick, back to the piano: diddle-de-diddle-de, bang, bang! Brilliant, that's it. That's the slo-mo shot in the movie, when suddenly you see everything blowing up and the music stops. That was the moment I had in my head."
"And then you get the line: "We're down, lads." That's the pilot's voice – the last thing that the survivors heard as they jumped from the back of the airship, from the rear power car, into the dark."