PLT OF AN SMA SEL ERRONEOUSLY PENETRATED AN ATA AIRSPACE WHILE ATTEMPTING TO STAY VFR.

Narrative

I DEPARTED FROM N99 FOR ERIE; ENRTE TO OSHKOSH; IN VFR CONDITIONS. WX WAS POOR TO THE W; S; AND E; BUT LOOKED OK ON OUR NWBOUND RTE. I CHOSE A GPS COURSE THAT PASSED WELL SW OF READING AND NE OF LANCASTER. AT A POINT S OF READING WE ENCOUNTERED LOWER CLOUDS AND RAIN SHOWERS DIRECTLY AHEAD. WX APPEARED BETTER TO THE R (N) SO DIVERTED THAT WAY TRYING TO TURN BACK W AGAIN AT THE FIRST OPPORTUNITY. REPEATED THIS A COUPLE OF TIMES; GETTING CLOSER TO READING. I WAS UNSURE OF MY DISTANCE FROM READING--COULD HAVE OBTAINED IT FROM THE GPS; BUT IN THE MARGINAL CONDITIONS I HAD ALL MY ATTN FOCUSED OUTSIDE AND DID NOT WANT TO TAKE THE TIME TO LOOK UP THE READING IDENTIFIER AND ENTER IT AS A WAYPOINT. I BELIEVED WE WERE STILL WELL CLR OF THE READING ATA TO THE S; BUT MONITORED THE TWR FREQ AS A PRECAUTION. PRESENTLY I HEARD THE TWR CALLING 'ACFT TO THE SW OF THE READING ARPT...' ASSUMED THEY WERE REFERRING TO ME AND RESPONDED; REQUESTING SPECIAL VFR TO LAND AT READING. AT THEIR REQUEST I HELD TO THE SW OF THE ARPT; SET UP THE GPS AND ILS; AND SHORTLY LANDED AT READING ON A SPECIAL VFR BASIS WITHOUT FURTHER INCIDENT. FOUND OUT AFTER LNDG THAT PRIOR TO THE FIRST RADIO EXCHANGE; I HAD ENTERED THE READING ATA WITHOUT CLRNC.