Narrative:

While en route to ord, we experienced severe turbulence at FL330. After descending out of FL370, ATC advised us of occasional moderate chop at FL330. Shortly thereafter, I notified the flight attendants of the possibility of some turbulence and to be ready to situation down when it started to get rough, once we were level at FL330. The ride was fairly smooth. We then received a clearance to descend to FL260. The first officer started to descend and it started to get a little bumpy. A few seconds after that is when we encountered the severe turbulence. We were unable to maintain our altitude or our descent. Our instruments indicated a vertical speed of approximately 2000 FPM climb and the aircraft climbed to approximately FL339. ATC asked us if we were having trouble maintaining altitude and of course we said yes. A second or two later, the aircraft started to descend at a rapid rate with a lot of chop as well. We descended to approximately FL310 when things started to settle down and we continued our descent to FL260. We checked with the flight attendants after the event and they informed us that all passenger were seated and that at that time we had no injuries. We continued to ord and the rest of the flight was uneventful. After we blocked in, a flight attendant reported to me that she had incurred an injury to her right wrist and her back. We discussed this issue with dispatch and maintenance. Supplemental information from acn 598723: aircraft pitch attitude varied by 5 degrees and bank angle was within 30 degrees. The radar during this time showed nothing more than light rain. The total event lasted between 30-40 seconds.

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Original NASA ASRS Text

Title: A B757 EXPERIENCES SEVERE TURB RESULTING IN A CABIN ATTENDANT INJURY.

Narrative: WHILE ENRTE TO ORD, WE EXPERIENCED SEVERE TURB AT FL330. AFTER DSNDING OUT OF FL370, ATC ADVISED US OF OCCASIONAL MODERATE CHOP AT FL330. SHORTLY THEREAFTER, I NOTIFIED THE FLT ATTENDANTS OF THE POSSIBILITY OF SOME TURB AND TO BE READY TO SIT DOWN WHEN IT STARTED TO GET ROUGH, ONCE WE WERE LEVEL AT FL330. THE RIDE WAS FAIRLY SMOOTH. WE THEN RECEIVED A CLRNC TO DSND TO FL260. THE FO STARTED TO DSND AND IT STARTED TO GET A LITTLE BUMPY. A FEW SECONDS AFTER THAT IS WHEN WE ENCOUNTERED THE SEVERE TURB. WE WERE UNABLE TO MAINTAIN OUR ALT OR OUR DSCNT. OUR INSTS INDICATED A VERT SPD OF APPROX 2000 FPM CLB AND THE ACFT CLBED TO APPROX FL339. ATC ASKED US IF WE WERE HAVING TROUBLE MAINTAINING ALT AND OF COURSE WE SAID YES. A SECOND OR TWO LATER, THE ACFT STARTED TO DSND AT A RAPID RATE WITH A LOT OF CHOP AS WELL. WE DSNDED TO APPROX FL310 WHEN THINGS STARTED TO SETTLE DOWN AND WE CONTINUED OUR DSCNT TO FL260. WE CHKED WITH THE FLT ATTENDANTS AFTER THE EVENT AND THEY INFORMED US THAT ALL PAX WERE SEATED AND THAT AT THAT TIME WE HAD NO INJURIES. WE CONTINUED TO ORD AND THE REST OF THE FLT WAS UNEVENTFUL. AFTER WE BLOCKED IN, A FLT ATTENDANT RPTED TO ME THAT SHE HAD INCURRED AN INJURY TO HER R WRIST AND HER BACK. WE DISCUSSED THIS ISSUE WITH DISPATCH AND MAINT. SUPPLEMENTAL INFO FROM ACN 598723: ACFT PITCH ATTITUDE VARIED BY 5 DEGS AND BANK ANGLE WAS WITHIN 30 DEGS. THE RADAR DURING THIS TIME SHOWED NOTHING MORE THAN LIGHT RAIN. THE TOTAL EVENT LASTED BTWN 30-40 SECONDS.

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.