Wake turbulence encounter on arrival at den.

Attributes
ACN	308895
Time
Date	199506
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : den
State Reference	CO
Altitude	msl bound lower : 13500 msl bound upper : 13500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : den
Operator	common carrier : air carrier
Make Model Name	Brasilia EMB-120 All Series
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 300 flight time total : 3400 flight time type : 200
ASRS Report	308895
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	inflight encounter other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : regained aircraft control
Consequence	other
Supplementary
Air Traffic Incident	other

Narrative:

ATC called traffic (B757) 5 mins prior to event. We were 4 1/2 mi in trail of the B757. The B757 descended into IMC and we lost sight of it. Shortly, we descended into IMC. A few mins later we experienced a 45 degree roll to the right. I have no idea how far ahead the B757 was when we rolled. Callback conversation with reporter revealed the following information: reporter participated in the wake turbulence structured callback program. Reporter stated that the shock of the wake was very strong, rolling his aircraft 50 degrees in bank. The duration was lengthy, lasting over 10 seconds. The question arises from the flight crew, can't something be done to keep following aircraft away from the wake of a larger aircraft in front of them. This flight crew was flying in IMC conditions and had no idea of where to move so as to avoid the wake. They hope there is a better way to separate traffic during an arrival. Flight path displacement was small, about 50 ft, but what felt significant to the reporter was the sharpness and severity of the roll. Both pilots grabbed for the controls. Aircraft responded well to the control inputs but was subject to the wake for a long duration.

Original NASA ASRS Text

Title: WAKE TURB ENCOUNTER ON ARR AT DEN.

Narrative: ATC CALLED TFC (B757) 5 MINS PRIOR TO EVENT. WE WERE 4 1/2 MI IN TRAIL OF THE B757. THE B757 DSNDED INTO IMC AND WE LOST SIGHT OF IT. SHORTLY, WE DSNDED INTO IMC. A FEW MINS LATER WE EXPERIENCED A 45 DEG ROLL TO THE R. I HAVE NO IDEA HOW FAR AHEAD THE B757 WAS WHEN WE ROLLED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR PARTICIPATED IN THE WAKE TURB STRUCTURED CALLBACK PROGRAM. RPTR STATED THAT THE SHOCK OF THE WAKE WAS VERY STRONG, ROLLING HIS ACFT 50 DEGS IN BANK. THE DURATION WAS LENGTHY, LASTING OVER 10 SECONDS. THE QUESTION ARISES FROM THE FLC, CAN'T SOMETHING BE DONE TO KEEP FOLLOWING ACFT AWAY FROM THE WAKE OF A LARGER ACFT IN FRONT OF THEM. THIS FLC WAS FLYING IN IMC CONDITIONS AND HAD NO IDEA OF WHERE TO MOVE SO AS TO AVOID THE WAKE. THEY HOPE THERE IS A BETTER WAY TO SEPARATE TFC DURING AN ARR. FLT PATH DISPLACEMENT WAS SMALL, ABOUT 50 FT, BUT WHAT FELT SIGNIFICANT TO THE RPTR WAS THE SHARPNESS AND SEVERITY OF THE ROLL. BOTH PLTS GRABBED FOR THE CTLS. ACFT RESPONDED WELL TO THE CTL INPUTS BUT WAS SUBJECT TO THE WAKE FOR A LONG DURATION.

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.