Air carrier encounters wake turbulence 12 mi behind B757 during descent.

Attributes
ACN	446627
Time
Date	199908
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : har.vortac
State Reference	PA
Altitude	msl single value : 23000
Environment
Flight Conditions	VMC
Weather Elements	Turbulence
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	MD-80 Super 80
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zob.artcc
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : commercial pilot : instrument
ASRS Report	446627
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp
Events
Anomaly	inflight encounter : wake turbulence other anomaly
Resolutory Action	controller : issued new clearance flight crew : regained aircraft control
Supplementary
Problem Areas	Environmental Factor Weather
Primary Problem	Environmental Factor

Narrative:

ATC facility: ZOB. Location: approximately 45 NM west of harrisburg, PA. During descent through FL230, a somewhat violent roll left, then right, with moderate buffet was encountered without any warning. Seatbelt sign was turned on immediately and a heading change to the south was requested from center to evade the contrail of aircraft 12 NM ahead of us per TCASII. Upon request for heading change and report of brief turbulence encounter to ZOB, the controller was incredulous as to the cause since he saw that the now idented B757 was 1500 ft below our altitude. On first noting the aircraft and TCASII, captain asked if that plane was also going to phl. ZOB said that it was, and captain requested additional in trail spacing at that time. Captain acting as PNF.

Original NASA ASRS Text

Title: ACR ENCOUNTERS WAKE TURB 12 MI BEHIND B757 DURING DSCNT.

Narrative: ATC FACILITY: ZOB. LOCATION: APPROX 45 NM W OF HARRISBURG, PA. DURING DSCNT THROUGH FL230, A SOMEWHAT VIOLENT ROLL L, THEN R, WITH MODERATE BUFFET WAS ENCOUNTERED WITHOUT ANY WARNING. SEATBELT SIGN WAS TURNED ON IMMEDIATELY AND A HDG CHANGE TO THE S WAS REQUESTED FROM CTR TO EVADE THE CONTRAIL OF ACFT 12 NM AHEAD OF US PER TCASII. UPON REQUEST FOR HDG CHANGE AND RPT OF BRIEF TURB ENCOUNTER TO ZOB, THE CTLR WAS INCREDULOUS AS TO THE CAUSE SINCE HE SAW THAT THE NOW IDENTED B757 WAS 1500 FT BELOW OUR ALT. ON FIRST NOTING THE ACFT AND TCASII, CAPT ASKED IF THAT PLANE WAS ALSO GOING TO PHL. ZOB SAID THAT IT WAS, AND CAPT REQUESTED ADDITIONAL IN TRAIL SPACING AT THAT TIME. CAPT ACTING AS PNF.

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.