Investigators say the two planes that collided over San Francisco Bay, causing one of them to crash into the water, were involved in a passing maneuver.
Howard Plagens of the National Transportation Safety Board said Monday that the pilot of a vintage Hawker Sea Fury TMK 20 heard a "thump" after the maneuver and immediately focused on trying to fly his own plane to safety.
The investigator says the pilot saw the Cessna 210 going down, but did not see it crash Sunday afternoon.
The Contra Costa County Sheriff's Office said searchers have located the Cessna under 13 feet of water, but the plane and its pilot haven't been recovered.
Plagens said the surviving pilot managed to land safely but he is shaken. The identities of the pilots have not been released.