Commuter has wake turbulence encounter on approach.

Attributes
ACN	319271
Time
Date	199510
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : dvv airport : den
State Reference	CO
Altitude	msl bound lower : 16000 msl bound upper : 16000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : dsm
Operator	common carrier : air carrier
Make Model Name	Beech 1900
Operating Under FAR Part	Part 135
Navigation In Use	Other Other
Flight Phase	descent : approach descent other
Route In Use	arrival star : star enroute airway : den
Flight Plan	IFR
Aircraft 2
Make Model Name	DC-10 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 250 flight time total : 4400 flight time type : 2600
ASRS Report	319217
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	inflight encounter other other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

We were operating as commuter inbound to den on the RAMMS1 arrival. We had been assigned to cross ramms at 16000 ft. I had heard an air carrier heavy on frequency approximately 10 mi from ramms, I noticed a jet 10 to 20 mi ahead turning onto the RAMMS1 arrival at what appeared to be co-altitude. I immediately thought of the wake threat but the heavy was so far away that it was barely visible. Approximately 2 min later, we encountered an umcommanded left roll to about 40 degree angle of bank. I would estimate the rate between 50 to 70 degree per second. I applied immediate coordination right 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 reporter revealed the following information: structured call back was done in which reporter 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 aircraft the type of aircraft 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 turbulence any time there is an aircraft ahead at co-altitude.

Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.