Small Aircraft; Low Wing; 1 Eng; Fixed Gear
Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 24; Flight Crew Total 575; Flight Crew Type 375
Communication Breakdown; Situational Awareness
ATC Issue All Types; Conflict NMAC
Flight Crew Took Evasive Action
Human Factors; Airspace Structure
My passenger and I were transiting OAK Class C at 2;500 feet from the NW in contact with the tower. We were given the usual instructions to cross the Oakland Coliseum and then turn right to cross the RWY 30 numbers. Before reaching the stadium we had/heard several radio calls for traffic. One plane passed underneath and to our left. For a second plane; we heard the tower unsuccessfully establishing communications and giving varying instructions on altitude to fly and calling out us as traffic. We then finally heard a clear answer from the other traffic; stating they had us sight directly ahead. Indeed! They approached and passed off to our right at an estimated 300 feet and our altitude or slightly higher. I managed to take only slight evasive action to my left. This is the closest encounter I have had in all my flying and it happened in Class C within 1/2 mile of the runways. I have reflected on how I could have reacted faster or attained better situational awareness earlier; but I do not recall the traffic call out for this ever being clearly presented such that a conflict was possible.
GA pilot reported a near-mid-air-collision while transitioning OAK airspace while in communication with the tower.