The single-engine Cessna 185 was heading to Canada when the engine stalled, forcing the pilot to make an emergency landing in the sea around 3:45 p.m., said Federal Aviation Administration spokesman Allen Kenitzer.
The Coast Guard received a distress call at 3:06 p.m. from the plane whose beacon alerted rescuers to the aircraft's whereabouts, which was a mile offshore and northwest of Morro Bay, Petty Officer Rachel Polish said.
She said the beacon, which was hooked to an international satellite system that detects and locate distress calls, was key in getting rescuers to the scene quickly.
Coast Guard helicopters and boats from San Francisco, Los Angeles, Monterrey and Morro Bay were dispatched. Aircraft from several other agencies helped pinpoint the overturned plane.
Rescuers from a San Francisco-based Coast Guard helicopter ultimately hoisted the pair from the water, Polish said.
A man in his 70s and his son in his 30s were rescued, Polish said. No other information on the two was released.
They were taken to Paso Robles, where they declined medical attention.
The plane got caught in a kelp field in the water, and it sank after the rescue, Kenitzer said.
The aircraft was registered to AirCapital Nevada Inc. of Carson City, Nevada. An after-hours call to the business was not immediately returned.