QUESTIONED CTL ZONE PENETRATION.

Narrative

THERE WAS A BROKEN TO OVCST LAYER OVER THE BAY AREA; TFC (IFR) WAS BACKED UP FOR 20 MINS. I DSNDED BELOW THE LAYER NEAR NAPA COUNTY ARPT; RPTING 2200' BROKEN AND 10 MI; CLEAR SKIES TO THE NW; DECIDING THAT IT WOULD BE QUICKER TO GET INTO OAK VFR. OAK WAS RPTING 1500' OVCST AND 10 MI VIS. I WAS FOLLOWING THE FREEWAY (880) S AT 1000-1200' MSL. I WAS TOLD BY BAY APCH TO STAY 3 MI N OF ALAMEDA NAS; WHICH I COMPLIED. UPON LNDG IN OAK I HEARD ANOTHER ACFT ON OAK TWR FREQ ASKING FOR A SPECIAL VFR THROUGH THE ALAMEDA CTL ZONE. THIS MEANS THAT ALAMEDA MUST HAVE BEEN RPTING LESS THAN A 1000' CEILING. I WAS FLYING AT 1000' WITH THE CEILING WELL ABOVE ME AND EXCELLENT VIS. AFTER HEARING THE OTHER ACFT RECEIVE THE SPECIAL VFR; I ASSUMED THAT I MUST HAVE FLOWN THROUGH THE ALAMEDA CTL ZONE WHEN THEY WERE RPTING LESS THAN VFR MINIMUMS; ALTHOUGH IT WAS OBVIOUSLY ABOVE THOSE MINIMUMS TO ME WHILE TRANSITIONING THE AREA. SO; I'M NOT SURE; BUT I MAY HAVE BEEN IN A CTL ZONE THAT WAS RPTING LESS THAN VFR MINIMUMS W/O A SPECIAL VFR CLRNC. NO REF TO THIS EVENT WAS MADE OVER THE RADIO BY BAY APCH OR OAK TWR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR STATES THAT NOBODY EVER QUESTIONED HIS ACTIONS. HE MERELY QUESTIONED BECAUSE OF HEARING REQUEST FOR SPECIAL VFR CLRNC AFTER LNDG. COMPANY REQUESTS USE OF VFR WHENEVER POSSIBLE TO SAVE TIME.