A BE40 CREW; AFTER LNDG AT DAY; WERE UNABLE TO NEGOTIATE THE EXIT; SLIDING OFF THE TXWY.

Narrative

FOLLOWING AN UNEVENTFUL FLT; VISUAL APCH; AND LNDG TO RWY 6L AT DAY; THE CAPT SLOWED THE ACFT ON THE RWY TO TAXI SPD AND BEGAN A R TURN ONTO TXWY Z. ABOUT 2/3 THE WAY THROUGH THE TURN I FELT THE ACFT LURCH FORWARD AND REALIZED WE WERE SLIDING. THE CAPT CYCLED THE BRAKES; THEN APPLIED THRUST REVERSERS IN AN EFFORT TO STOP THE ACFT. THE ACFT SLID STRAIGHT AHEAD OFF THE TXWY BTWN TAXI LIGHTS INTO AN OPEN AREA OF SNOW-COVERED GRASS. THE TWR WAS NOTIFIED AND WE ELECTED TO CALL FOR A TUG RATHER THAN TAXI OUT OF THE GRASS; AS WE COULD NOT DETERMINE WHAT MIGHT BE HIDDEN UNDER THE 3 INCHES OF FRESH SNOW. ARPT OPS VEHICLES ARRIVED A SHORT TIME LATER; AND WE OBSERVED THEM SLIDE ON THE TXWY AS WELL. SAND TRUCKS WERE DISPATCHED AND TREATED THE AREA BEFORE THE TUB ARRIVED. ANOTHER ACFT LANDED A FEW MINS AFTER US ON THE SAME RWY AND EXITED ANOTHER TXWY AND RPTED THAT BRAKING ACTION WAS POOR TO NIL THERE AS WELL. ATIS WAS RECEIVED PRIOR TO THE VISUAL APCH; AND THERE WAS NO MENTION OF BRAKING ADVISORIES. THE RWY AND ASSOCIATED TXWYS APPEARED TO HAVE BEEN PLOWED RECENTLY; AND APPEARED TO BE MOSTLY CLR WITH A FEW PATCHES OF THIN SNOW. ON FURTHER INSPECTION OF TXWY Z; THE PAVEMENT WAS COVERED BY A THIN LAYER OF CLR ICE. AN ARPT OPS WORKER OFFERED THE OPINION THAT THE TXWY HAD BEEN PLOWED AN HR OR SO PREVIOUSLY; BUT THE SUN HAD COME OUT AND MAY HAVE HELPED TO MELT SOME OF THE SNOW; WHICH THEN REFROZE. NO INJURIES OR DAMAGE WERE CAUSED DURING THIS EVENT. OUR TAXI SPD WAS APPROPRIATE FOR THE PERCEIVED CONDITIONS. ADDITIONAL CHKS BY THE ARPT VEHICLES OF THE TXWYS MIGHT HAVE PREVENTED THIS OCCURRENCE.