Narrative:

In and out of clouds, the captain illuminated the seat belt sign and made appropriate PA. The only returns on radar were approximately 60 mi north. Light chop developed, which rapidly escalated to moderate to severe and culminated in one especially severe jolt. Just before the severe jolt, in and out of cirrus, I saw a build-up slightly off to the right. This was not showing on radar. We reported severe turbulence to ATC and diverted to okc after cabin crew reported injuries. Descent, approach, and landing were normal with aircraft handling normal. 4 flight attendants injured. There was just light chop being reported in the general area. There were no returns within 60 degrees of the nose. Every tool and cues didn't give us any indication that we could expect anything more than light chop. Supplemental information from acn 403022: the seatbelt sign was on and all passenger were seated and strapped. The flight attendants were not seated at the time. We were en route to lax from pit and diverted to okc.

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Original NASA ASRS Text

Title: CABIN ATTENDANTS ON B757-200 INJURED WHEN ACFT ENCOUNTERED SEVERE JOLT OF TURB.

Narrative: IN AND OUT OF CLOUDS, THE CAPT ILLUMINATED THE SEAT BELT SIGN AND MADE APPROPRIATE PA. THE ONLY RETURNS ON RADAR WERE APPROX 60 MI N. LIGHT CHOP DEVELOPED, WHICH RAPIDLY ESCALATED TO MODERATE TO SEVERE AND CULMINATED IN ONE ESPECIALLY SEVERE JOLT. JUST BEFORE THE SEVERE JOLT, IN AND OUT OF CIRRUS, I SAW A BUILD-UP SLIGHTLY OFF TO THE R. THIS WAS NOT SHOWING ON RADAR. WE RPTED SEVERE TURB TO ATC AND DIVERTED TO OKC AFTER CABIN CREW RPTED INJURIES. DSCNT, APCH, AND LNDG WERE NORMAL WITH ACFT HANDLING NORMAL. 4 FLT ATTENDANTS INJURED. THERE WAS JUST LIGHT CHOP BEING RPTED IN THE GENERAL AREA. THERE WERE NO RETURNS WITHIN 60 DEGS OF THE NOSE. EVERY TOOL AND CUES DIDN'T GIVE US ANY INDICATION THAT WE COULD EXPECT ANYTHING MORE THAN LIGHT CHOP. SUPPLEMENTAL INFO FROM ACN 403022: THE SEATBELT SIGN WAS ON AND ALL PAX WERE SEATED AND STRAPPED. THE FLT ATTENDANTS WERE NOT SEATED AT THE TIME. WE WERE ENRTE TO LAX FROM PIT AND DIVERTED TO OKC.

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.