Horner's assistant, Sylvia Patrycja, confirmed the news on Facebook, saying, "We have lost an amazing person with a huge heart and unbelievable talent. He died doing what he loved. Thank you for all your support and love and see you down the road."
The small plane that Horner was piloting crashed about 60 miles north of Santa Barbara, in a remote area.
Horner won an Oscar for Best Original Song for My Heart Will Go On and one for the Best Original Score for Titanic.
Horner once said, "I'm different from some other composers because I don't look at this as just a job. I see music as art."
His work also included music for Avatar, A Beautiful Mind, Field of Dreams, An American Tail, Legends of the Fall, and Aliens.
