An A320 following a B757 in ZMP airspace, flies into the wake turbulence of the preceding B757.

Attributes
ACN	409475
Time
Date	199807
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : eau
State Reference	WI
Altitude	msl bound lower : 20000 msl bound upper : 30000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp
Operator	common carrier : air carrier
Make Model Name	A320
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 16000 flight time type : 50
ASRS Report	409475
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	inflight encounter other
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time none taken : detected after the fact
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

During descent on EAU2 arrival into msp we encountered 2 uncommanded roll excursions. We were in the clear with no significant WX in descent between FL300-200. Both events felt as if we were in some type of wake turbulence. First event rolled us to the left and airbus, which has positive static stability and was on autoplt, was slow to return to level flight. Second event was so uncomfortable that first officer, who was flying, clicked off autoplt and attempted to level wings, but was unable to do so. We observed another aircraft, on the TCASII, on descent 7-8 mi in front of us. ATC reported that aircraft was a B757.

Original NASA ASRS Text

Title: AN A320 FOLLOWING A B757 IN ZMP AIRSPACE, FLIES INTO THE WAKE TURB OF THE PRECEDING B757.

Narrative: DURING DSCNT ON EAU2 ARR INTO MSP WE ENCOUNTERED 2 UNCOMMANDED ROLL EXCURSIONS. WE WERE IN THE CLR WITH NO SIGNIFICANT WX IN DSCNT BTWN FL300-200. BOTH EVENTS FELT AS IF WE WERE IN SOME TYPE OF WAKE TURB. FIRST EVENT ROLLED US TO THE L AND AIRBUS, WHICH HAS POSITIVE STATIC STABILITY AND WAS ON AUTOPLT, WAS SLOW TO RETURN TO LEVEL FLT. SECOND EVENT WAS SO UNCOMFORTABLE THAT FO, WHO WAS FLYING, CLICKED OFF AUTOPLT AND ATTEMPTED TO LEVEL WINGS, BUT WAS UNABLE TO DO SO. WE OBSERVED ANOTHER ACFT, ON THE TCASII, ON DSCNT 7-8 MI IN FRONT OF US. ATC RPTED THAT ACFT WAS A B757.

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.