Maybe you’re thinking of the crash of a P3 April 12, 1973 onto the Sunnyvale Municipal Golf Course next to CA-101. The P3 was doing touch-and-goes after a mission off Big Sur. They collided with a NASA Convair 990. 16 of 17 people on the two aircraft died.
The safety record of the P-3 operations at Moffett was excellent. This collision was the first and only crash of a P-3 near the airfield between the early 1960s and 1994 when the Navy decommissioned Moffett.
No, the aircraft I saw was for sure an Electra-type airframe. I saw it when I was crossing directly over the SFO airport in a Mooney. Thought at the time it might be a scrapped airliner that was used for crew ditching drills. Then about the same time, a Japan Airlines DC-8 landed “a little short”, that is, in the bay right on the final approach path. It sat out there with the rudder sticking up out of the water for quite a while.