Narrative:

We were level at FL310; 10 NM behind an air carrier call sign Y also at FL310; when he reported encountering wake turbulence from an air carrier; a B777; 7 NM in front of them. Air carrier Y stated he would be offsetting to the north. I noted his comments and was comfortable as the winds aloft were out of the south. I observed air carrier Y turning south; instead of his stated north offset; and advised ATC. We suddenly encountered his wake turbulence. I immediately illuminated the seat belt sign followed by an announcement. I was later advised by our purser that during the wake encounter; she lost her balance and her head hit the first class closet wall. She stated her neck was getting stiff.

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Original NASA ASRS Text

Title: A B777-200 ENCOUNTERED WAKE TURB IN TRAIL OF ANOTHER ACR ACFT. FLT ATTENDANT WAS SLIGHTLY INJURED WHEN SHE FELL DURING THE WAKE ENCOUNTER.

Narrative: WE WERE LEVEL AT FL310; 10 NM BEHIND AN ACR CALL SIGN Y ALSO AT FL310; WHEN HE RPTED ENCOUNTERING WAKE TURB FROM AN ACR; A B777; 7 NM IN FRONT OF THEM. ACR Y STATED HE WOULD BE OFFSETTING TO THE N. I NOTED HIS COMMENTS AND WAS COMFORTABLE AS THE WINDS ALOFT WERE OUT OF THE S. I OBSERVED ACR Y TURNING S; INSTEAD OF HIS STATED N OFFSET; AND ADVISED ATC. WE SUDDENLY ENCOUNTERED HIS WAKE TURB. I IMMEDIATELY ILLUMINATED THE SEAT BELT SIGN FOLLOWED BY AN ANNOUNCEMENT. I WAS LATER ADVISED BY OUR PURSER THAT DURING THE WAKE ENCOUNTER; SHE LOST HER BAL AND HER HEAD HIT THE FIRST CLASS CLOSET WALL. SHE STATED HER NECK WAS GETTING STIFF.

Data retrieved from NASA's ASRS site as of January 2009 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.