Narrative:

While en route at cruise at 15000 ft turbulence was encountered. There were no sigmets for this altitude or area. There was no convective activity or PIREPS for turbulence. There was a SIGMET for ocn/severe turbulence below 11000 ft in the jfk area but nothing for the area we were flying in. ATC passed along 1 PIREP for light to moderate turbulence in an area south of our route and lower. Conditions were smooth before our encounter. Based on the PIREP the seat belt sign was on and the passenger were instructed to check the security of their seat belts. The actual turbulence encounter was moderate to severe. The autoplt was engaged and stayed engaged. The initial encounter lasted less than 60 seconds. We encountered at least 5 degrees nose down and up pitch change plus 30 degrees of bank. There was never loss of control of the aircraft. After the initial contact, turbulence was only light to moderate. The flight attendant informed us that she hit her head on the roof of the cabin. She also stated that 2 passenger were injured. We declared an emergency and landed in pvd. The 2 injured passenger and flight attendant were transported to local hospital. It is my understanding that all 3 were released without serious injury. I think the cause of turbulence was large temperature changes associated with the back side of a very weak unforecast front. Had we known of the severity of the turbulence we could have 1) tried to avoid it, 2) specifically instructed the flight attendant to belt herself in. We did not anticipate this much turbulence and also assumed that my announcement to the passenger would have indicated to the flight attendant to return to her seat and buckle in.

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Original NASA ASRS Text

Title: PAX AND CABIN CREW INJURED DURING ENCOUNTER WITH TURB.

Narrative: WHILE ENRTE AT CRUISE AT 15000 FT TURB WAS ENCOUNTERED. THERE WERE NO SIGMETS FOR THIS ALT OR AREA. THERE WAS NO CONVECTIVE ACTIVITY OR PIREPS FOR TURB. THERE WAS A SIGMET FOR OCN/SEVERE TURB BELOW 11000 FT IN THE JFK AREA BUT NOTHING FOR THE AREA WE WERE FLYING IN. ATC PASSED ALONG 1 PIREP FOR LIGHT TO MODERATE TURB IN AN AREA S OF OUR RTE AND LOWER. CONDITIONS WERE SMOOTH BEFORE OUR ENCOUNTER. BASED ON THE PIREP THE SEAT BELT SIGN WAS ON AND THE PAX WERE INSTRUCTED TO CHK THE SECURITY OF THEIR SEAT BELTS. THE ACTUAL TURB ENCOUNTER WAS MODERATE TO SEVERE. THE AUTOPLT WAS ENGAGED AND STAYED ENGAGED. THE INITIAL ENCOUNTER LASTED LESS THAN 60 SECONDS. WE ENCOUNTERED AT LEAST 5 DEGS NOSE DOWN AND UP PITCH CHANGE PLUS 30 DEGS OF BANK. THERE WAS NEVER LOSS OF CTL OF THE ACFT. AFTER THE INITIAL CONTACT, TURB WAS ONLY LIGHT TO MODERATE. THE FLT ATTENDANT INFORMED US THAT SHE HIT HER HEAD ON THE ROOF OF THE CABIN. SHE ALSO STATED THAT 2 PAX WERE INJURED. WE DECLARED AN EMER AND LANDED IN PVD. THE 2 INJURED PAX AND FLT ATTENDANT WERE TRANSPORTED TO LCL HOSPITAL. IT IS MY UNDERSTANDING THAT ALL 3 WERE RELEASED WITHOUT SERIOUS INJURY. I THINK THE CAUSE OF TURB WAS LARGE TEMP CHANGES ASSOCIATED WITH THE BACK SIDE OF A VERY WEAK UNFORECAST FRONT. HAD WE KNOWN OF THE SEVERITY OF THE TURB WE COULD HAVE 1) TRIED TO AVOID IT, 2) SPECIFICALLY INSTRUCTED THE FLT ATTENDANT TO BELT HERSELF IN. WE DID NOT ANTICIPATE THIS MUCH TURB AND ALSO ASSUMED THAT MY ANNOUNCEMENT TO THE PAX WOULD HAVE INDICATED TO THE FLT ATTENDANT TO RETURN TO HER SEAT AND BUCKLE IN.

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.