AN ENCOUNTER WITH SEVERE TURB RESULTING IN PAX INJURY.

Narrative

I WAS THE CAPT AND WAS THE PLT MONITORING. WE WERE AT CRUISE AT FL390; .78 MACH. THE CONDITIONS WERE IMC AND WE WERE FLYING IN A HAZE LAYER. RADAR WAS ON AND HAD BEEN ON ENTIRE FLT. NO RETURNS WERE ON THE RADAR; AND WE HAD EXERCISED THE TILT AND RANGE THROUGHOUT THE FLT. WE BROKE OUT OF IMC MOMENTARILY AND NOTICED A BUILDUP DIRECTLY IN FRONT OF US; WHICH DID NOT APPEAR LARGE OR WELL-DEVELOPED. ITS TOPS APPEARED AT OUR ALT; BUT HAD NOT GENERATED A RADAR RETURN. THERE WAS NO WAY TO MANEUVER AROUND THE BUILDUP. THE FO TURNED ON THE SEATBELT SIGN. A FEW SECONDS LATER WE ENCOUNTERED 'SEVERE TURB.' WE GAINED APPROX 500 FT AND THE ACFT BANKED 30 DEGS TO THE R. THE FO WAS ABLE TO MAINTAIN POSITIVE CTL OF THE ACFT AT ALL TIMES. THE TURB LASTED APPROX 3-5 SECONDS. I CHKED WITH THE FLT ATTENDANTS FOR ANY INJURIES. SHE RPTED 4 OR 5 INJURIES; AND THAT SEVERAL PAX WERE STANDING IN THE AISLE AT THE TIME. THE FLT ATTENDANTS TENDED TO THE INJURIES. WE DECLARED AN EMER. I CHKED AGAIN WITH THE FLT ATTENDANTS AS TO THE EXTENT OF THE INJURIES. SHE THOUGHT (AT THE TIME) INJURIES WERE MINOR BUMPS; BRUISES; SMA AND DID NOT WARRANT A DIVERT. WE WERE CLRED DIRECT TO IAH WITH NO FURTHER DELAYS. PARAMEDICS MET THE ACFT AND TENDED TO THE PAX. WE SPOKE WITH MAINT AND WROTE UP THE TURB IN THE LOGBOOK. COORD OF FLT ATTENDANT AND COMPANY AND EMER SVCS WAS EXCELLENT.