COMMUTER HAS WAKE TURB ENCOUNTER ON APCH.

Narrative

WE WERE OPERATING AS COMMUTER INBOUND TO DEN ON THE RAMMS1 ARR. WE HAD BEEN ASSIGNED TO CROSS RAMMS AT 16000 FT. I HAD HEARD AN ACR HVY ON FREQ APPROX 10 MI FROM RAMMS; I NOTICED A JET 10 TO 20 MI AHEAD TURNING ONTO THE RAMMS1 ARR AT WHAT APPEARED TO BE CO-ALT. I IMMEDIATELY THOUGHT OF THE WAKE THREAT BUT THE HVY WAS SO FAR AWAY THAT IT WAS BARELY VISIBLE. APPROX 2 MIN LATER; WE ENCOUNTERED AN UMCOMMANDED L ROLL TO ABOUT 40 DEG ANGLE OF BANK. I WOULD ESTIMATE THE RATE BTWN 50 TO 70 DEG PER SECOND. I APPLIED IMMEDIATE COORD R AILERON/RUDDER AND RIGHTED THE SHIP. NO FURTHER WAKE WAS EXPERIENCED. THERE MUST HAVE BEEN EASILY 20 PLUS MI IN TRAIL SEPARATION; AMAZING! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: STRUCTURED CALL BACK WAS DONE IN WHICH RPTR STATED THE AIR WAS UNUSUALLY STILL IN THE DEN AREA. HE BELIEVES THAT IS WHY THE WAKE STAYED AROUND LONG ENOUGH FOR THE ENCOUNTER. FEELS IT WOULD BE ADVISABLE TO INFORM ANY IN TRAIL ACFT THE TYPE OF ACFT AHEAD. HE HAD A SENSE OF POSSIBLE WAKE WHEN HE FIRST SAW THE DC10 TURN ONTO THE STAR AHEAD. NOW HE WILL BE EXCEPTIONALLY ALERT TO WAKE TURB ANY TIME THERE IS AN ACFT AHEAD AT CO-ALT.