The two men started out in Hollywood at around the same time and first teamed up for Aliens in 1986. Cameron went on to hire Horner to create the scores for Titanic and Avatar, and admits he was thinking about his friend and colleague when he heard the news of the tragedy in California.

In a statement to The Hollywood Reporter, the director writes, "The beginning and end of his filmography are films that he did, or would have done, with me. It's a curious bookend. We both started out on the same film in 1980, and his last listed films are the Avatar sequels, which he would have begun later this year.

"We only worked together three times, and each time it was a decade apart - Aliens in the mid-eighties, Titanic in the mid-90s and Avatar in '08 and '09.

"I met him on Battle Beyond the Stars, which was my first film getting a paycheck. I entered as a junior model builder and ended up three months later as production designer, which could only happen on a Roger Corman production. The score was absolutely the best thing about the film. It was a full-on orchestral score, not some rinky-dink (cheap) synth score. After that I ran into him a few times."

But Cameron admits his relationship with the revered composer wasn't always a good one, adding, "He was the obvious choice to do Aliens but we got off to a bad start. It was a time in his career when he was overbooking himself. He recorded the whole score in a day and a half in London and then he was gone. We wound up editing the score ourselves. He got an Academy Award nomination, so he thanked me afterwards, but we both allowed that was not the best way to do things.

"When I was doing Titanic, he had just done Apollo 13 and Braveheart. I thought, 'I don't care what happened, I want to work with James'. We had this very cautious meeting where we were falling all over ourselves to be polite. We laughed about it so much in subsequent years. But we developed a very transparent means of communication which made for a great working relationship.

"He totally committed himself to the movie. He blocked out his schedule and sat down and watched maybe 30 hours of raw dailies to absorb the feeling of the film.

"I drove over to his house and he sat at the piano and said, 'I see this as the main theme for the ship'. He played it once through and I was crying. Then he played Rose's theme and I was crying again. They were so bittersweet and emotionally resonant. He hadn't orchestrated a thing and I knew it was going to be one of cinema's great scores. No matter how the movie turned out, and no one knew at that point - it could have been a dog - I knew it would be a great score."

Cameron concludes his tribute with a regret, adding, "I didn't get to go to most of the orchestral scoring sessions. I made it to one. But the orchestra loved him. He always worked with a lot of the same players. Unlike most composers, he also conducted. He was classically trained. It was his room and they were sure to make something great. If I thought maybe there was something that wasn't supporting the picture, he could turn on a dime and make it work."

And the filmmaker recalls his last meeting with Horner after very special concert in London: "In April, they did a night at the Royal Albert Hall where the orchestra did the entire Titanic score live to the movie. James was there to take his bows. (Producer) Jon Landau and I went to London just for the concert, and we had a kind of reunion.

"It was emotional and I'm glad that was my last personal memory of James. They had to subtitle the film because when the orchestra was playing, you couldn't hear the words. I thought, 'This is how James would have imagined it'."