COMMUTER SMT HAS NMAC WITH SMA JUST OUTSIDE THE ARSA.

Narrative

THE FLT PROCEEDED UNEVENTFULLY UNTIL WE BEGAN OUR VFR DSCNT APCHING THE N SHORE OF CAY ISLAND. NEW YORK APCH AIRSPACE IS CHARACTERISTICALLY CONGESTED WITH A MIX OF AIRLINE; COMMUTER; BUSINESS; PLEASURE; MIL AND TRAINING FLTS; ESPECIALLY MID-AFTERNOON ON A GOOD VFR DAY. BOTH THE CAPT AND I WERE CONSTANTLY SCANNING THE AREA FOR TFC. UPON COMPLETING THE COCKPIT ITEMS I INFORMED HIM I'D BE LEAVING THE FREQ TO CALL COMPANY AND BRIEF THE PAXS AND WE CONFIRMED HE'D GUARD THE #1 COM FREQ (STANDARD COMPANY PROC). AS I MOVED MY AUDIO SELECTOR KNOB TO THE 'PA' DETENT I SCANNED L FOR TFC AND NOTICED CAPT'S HEAD TURNED AWAY; ALSO CHKING L FOR TFC. SCANNING THROUGH 12 O'CLOCK; I GLANCED DOWN TO CONFIRM MY SELECTOR KNOB ON 'PA' AND RESUMED SCAN FROM 12 O'CLOCK CLOCKWISE RETURNING FROM 5 O'CLOCK BACK TOWARD FRONT I SAW A BLUE AND WHITE SMA APPEAR FROM THE 3 O'CLOCK POS CONVERGING AND VERY CLOSE. (HE HAD APPARENTLY BEEN BLOCKED BY THE WING AND ENG NACELLE DURING MY FIRST SWEEP OF THE AREA). I YELLED 'HARD L' TO CAPT; COMMANDING EVASIVE ACTION AND EXPECTING AN IMMEDIATE RESPONSE. I REALIZED IN AN INSTANT HE COULDN'T HEAR ME SINCE OUR AUDIO PANELS AUTOMATICALLY CUT OUT THE CREW INTERPHONE/HOT MIKE FUNCTION WHEN THE 'PA' FEATURE IS SELECTED. A QUICK GLANCE IN HIS DIRECTION CONFIRMED HE WAS STILL LOOKING OUT THE L WINDOW; UNAWARE OF THE CONVERGING TFC. WITH NO OPTIONS LEFT I GRABBED THE YOKE AND RUDDER PEDALS AND ROLLED DECISIVELY INTO A CLBING L TURN WITH ABOUT 30 DEG BANK ANGLE. I LOOKED BACK IN TIME TO SEE THE SMA ROLL INTO A DIVING L TURN. HE MUST HAVE SEEN US AT THE LAST MOMENT AS WELL. THE SMA PASSED WELL CLR; BELOW AND BEHIND OUR ACFT; THOUGH CLOSE ENOUGH THAT I COULD PLAINLY READ THE LCL FLYING SCHOOL LOGO ON THE SIDE OF THE ACFT.