VFR FLT WITHOUT FILING RESULTS IN POTENTIAL CONFLICT WITH SMA ALSO VFR.

Narrative

WE HAD JUST DEPARTED THE WASHINGTON TCA TO THE N ENRTE TO BWI. WE HAD BEEN WORKING WITH ADW APCH AND TWR FOR TFC ADVISORIES AND HAD REQUESTED A FREQ CHANGE TO BWI APCH WHICH WAS GRANTED AS WE WERE CLR OF THE TCA. NO TFC WAS RPTED TO US. IMMEDIATELY AFTER THE PNF (LEFT SEAT) CHANGED RADIO FREQS HE LOOKED OUT THE LEFT WINDOW AND CALLED TFC AT 10 O'CLOCK. I LOOKED OVER AND SAW A SINGLE ENG SMA IN A HARD LEFT TURN; AND I STARTED A HARD RIGHT TURN TO AVOID THE SMA. THE TFC WAS AT THE SAME ALT AS WE WERE. THERE ARE SEVERAL FACTORS THAT CONTRIBUTE TO THIS KIND OF EVENT IN THIS AREA. FIRST; MANY LIGHT AIRPLANE PLTS TRY TO FLY BTWN BWI; ADW AND TIPTON AAF W/O ESTABLISHING RADIO CONTACT WITH ANYONE. WHILE LEGAL; I THINK THIS PRACTICE IS UNSAFE. SECOND; THE AIRSPACE PLAN IN THIS AREA DOES NOT LEND ITSELF TO SAFE VFR OPS FOR TFC PASSING THROUGH ADW AIRSPACE ENRTE TO BWI SINCE ADW DOES NOT HAVE THE CAPABILITY TO HAND OFF VFR TFC TO BWI APCH. THIS FORCES ANYONE NBOUND AT LOW ALT TO BE TERMINATED BY ADW AND HAVE TO ESTABLISH CONTACT WITH BWI ON THEIR OWN. THIS LEAVES A GAP IN THE RADAR COVERAGE FOR THOSE OF US THAT LIKE TOO USE ALL THE AVAILABLE MEANS FOR SAFE FLT. I WOULD LIKE TO COMMENT ON THE PLT OF THE SMA AS HE MADE A LEFT TURN TO AVOID US; WHICH MADE THE SITUATION WORSE WHEN HE SHOULD HAVE TURNED RIGHT AS PER THE FAR'S. HAD HE MADE A RIGHT TURN NO CONFLICT WOULD HAVE OCCURRED. OUR ACFT DESIGN ALSO CONTRIBUTED TO THE CLOSENESS AS THERE IS A LARGE POST BTWN THE COPLT DOOR AND WINDSHIELD WHICH CREATES A BLIND SPOT FOR THE PLT IN THE RIGHT SEAT. I TALKED WITH THE SUPVR AT ADW TWR AND HIS COMMENT TO ME WAS THAT THIS IS A COMMON OCCURRENCE IN THS AREA BECAUSE OF THE LIGHT ACFT TRYING TO AVOID THE TCA. IF THERE WAS BETTER COORD AVAILABLE BTWN ADW AND BWI WE WOULD GLADLY USE IT TO THE FULLEST EXTENT. WE HAVE BEEN TOLD THAT THERE IS GOING TO BE A CHANGE IN THE WASHINGTON TCA NEXT YR WHICH WE WELCOME; AND HOPE THAT THIS WILL HELP ALLEVIATE SOME OF THE PROBS IN THIS AREA.