How Did John Hubley Die?

John Kirkham Hubley was an American animated film director, art director, producer, and writer, known for his work with the United Productions of America (UPA) and his own independent studio, Storyboard, Inc.. A pioneer and innovator in the American animation industry, Hubley pushed for more visually and emotionally complex films than the productions at that time of Walt Disney Productions and Warner Bros. Cartoons.