The senior executive at the Toyota Motor Corporation who oversaw its hybrid vehicle program died Saturday when a small aircraft he was piloting crashed into the Pacific Ocean near San Pedro, Calif.

David Hermance, the executive engineer who oversaw Toyota’s hybrid vehicle program, and who is credited for the success of the Toyota Prius, died in plane crash on November 25, The New York Times reports.

It’s unclear how Hermance’s death might affect the company’s hybrid program.