DC9-30 aircraft in descent encountered severe wake turbulence from preceding B757. Flight crew experienced severe jolt and roll, but aircraft was on autoplt and it was able to recover quickly, though reporter captain thinks marginally. Formal wake turbulence callback was completed.

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Attributes
ACN	358896
Time
Date	199701
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : aml
State Reference	VA
Altitude	msl bound lower : 19000 msl bound upper : 19000
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	DC-9 30
Operating Under FAR Part	Part 121
Flight Phase	descent other
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	cruise 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 : 210 flight time total : 16000 flight time type : 12500
ASRS Report	358896
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	inflight encounter other
Independent Detector	other flight crewa
Resolutory Action	flight crew : exited adverse environment
Consequence	other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

Experienced sudden severe roll and jolt that the autoplt barely recovered from. The jolt was severe, but fortunately, the seatbelt sign was on and no injuries occurred. I had the first officer ask what traffic we were following and ATC told us a B757 12.6 mi ahead. I requested further spacing and reported severe wake turbulence. This is my third incident of severe turbulence following new generation boeing aircraft. The first was behind a B757 in approximately 1990 or 1989 and was reported to company (airline). The second was about 6-9 months ago behind (15 mi) a B747-400. All 3 involved momentary aircraft control difficulty and turbulence severe enough to hurt unseatbelted passenger, but didn't. This is serious stuff and I don't see the problem being addressed. What would happen to an aircraft at maximum weight and minimum airspeed and performance?

Original NASA ASRS Text

Title: DC9-30 ACFT IN DSCNT ENCOUNTERED SEVERE WAKE TURB FROM PRECEDING B757. FLC EXPERIENCED SEVERE JOLT AND ROLL, BUT ACFT WAS ON AUTOPLT AND IT WAS ABLE TO RECOVER QUICKLY, THOUGH RPTR CAPT THINKS MARGINALLY. FORMAL WAKE TURB CALLBACK WAS COMPLETED.

Narrative: EXPERIENCED SUDDEN SEVERE ROLL AND JOLT THAT THE AUTOPLT BARELY RECOVERED FROM. THE JOLT WAS SEVERE, BUT FORTUNATELY, THE SEATBELT SIGN WAS ON AND NO INJURIES OCCURRED. I HAD THE FO ASK WHAT TFC WE WERE FOLLOWING AND ATC TOLD US A B757 12.6 MI AHEAD. I REQUESTED FURTHER SPACING AND RPTED SEVERE WAKE TURB. THIS IS MY THIRD INCIDENT OF SEVERE TURB FOLLOWING NEW GENERATION BOEING ACFT. THE FIRST WAS BEHIND A B757 IN APPROX 1990 OR 1989 AND WAS RPTED TO COMPANY (AIRLINE). THE SECOND WAS ABOUT 6-9 MONTHS AGO BEHIND (15 MI) A B747-400. ALL 3 INVOLVED MOMENTARY ACFT CTL DIFFICULTY AND TURB SEVERE ENOUGH TO HURT UNSEATBELTED PAX, BUT DIDN'T. THIS IS SERIOUS STUFF AND I DON'T SEE THE PROB BEING ADDRESSED. WHAT WOULD HAPPEN TO AN ACFT AT MAX WT AND MINIMUM AIRSPD AND PERFORMANCE?

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.