Narrative:

Cruising between layers we noticed some activity on radar up ahead along our route. I was nfp and was preparing to make a passenger announcement and turn seat belt sign back on. I also planned to ask for a deviation from ATC, but what we saw on radar really didn't appear like much at all, so there was no hurry. 10-15 mi before reaching the WX being displayed, and just before I started to make the passenger announcement we encountered severe turbulence. With autoplt still on aircraft, at 1 point was in a 45 degree bank and losing altitude. I told first officer to disengaged autoplt and hand-fly, which he did. It was a very rough ride, and our maximum altitude loss was 500'. I had switched on the seat belt sign immediately upon encountering the turbulence, and luckily all passenger were in their seats with their belts fastened. Our F/a was not however, and ended up on the floor, but she was not injured. Rain began sooner than the rain on our scope showed up at, and the ride was certainly rougher than what we anticipated from the looks of the WX on the screen. I told ATC we had lost some altitude due to turbulence and apparently there had been no traffic conflict. I made an apologetic passenger announcement once we were through the ride and called the first officer on the interphone to see if anybody was hurt. Thankfully, everybody was fine. I realized once again that radar doesn't show turbulence or give all clues to where it might be or its severity. Clearly I waited too long to prepare the cabin and/or request a deviation from ATC. Contributing to this incident was my mental fatigue due to having taken a 6 month chkride just 2 nights before and then being assigned this trip which included 13 hours duty and 8+ hours of flight time on day #2--day of this event. I was, in this case, behind the aircraft a little, and underestimated the WX: complacency.

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Original NASA ASRS Text

Title: ACR LTT ALT DEVIATION EXCURSION FROM CLRNC ALT IN SEVERE TURBULENCE.

Narrative: CRUISING BTWN LAYERS WE NOTICED SOME ACTIVITY ON RADAR UP AHEAD ALONG OUR RTE. I WAS NFP AND WAS PREPARING TO MAKE A PAX ANNOUNCEMENT AND TURN SEAT BELT SIGN BACK ON. I ALSO PLANNED TO ASK FOR A DEVIATION FROM ATC, BUT WHAT WE SAW ON RADAR REALLY DIDN'T APPEAR LIKE MUCH AT ALL, SO THERE WAS NO HURRY. 10-15 MI BEFORE REACHING THE WX BEING DISPLAYED, AND JUST BEFORE I STARTED TO MAKE THE PAX ANNOUNCEMENT WE ENCOUNTERED SEVERE TURB. WITH AUTOPLT STILL ON ACFT, AT 1 POINT WAS IN A 45 DEG BANK AND LOSING ALT. I TOLD F/O TO DISENGAGED AUTOPLT AND HAND-FLY, WHICH HE DID. IT WAS A VERY ROUGH RIDE, AND OUR MAX ALT LOSS WAS 500'. I HAD SWITCHED ON THE SEAT BELT SIGN IMMEDIATELY UPON ENCOUNTERING THE TURB, AND LUCKILY ALL PAX WERE IN THEIR SEATS WITH THEIR BELTS FASTENED. OUR F/A WAS NOT HOWEVER, AND ENDED UP ON THE FLOOR, BUT SHE WAS NOT INJURED. RAIN BEGAN SOONER THAN THE RAIN ON OUR SCOPE SHOWED UP AT, AND THE RIDE WAS CERTAINLY ROUGHER THAN WHAT WE ANTICIPATED FROM THE LOOKS OF THE WX ON THE SCREEN. I TOLD ATC WE HAD LOST SOME ALT DUE TO TURB AND APPARENTLY THERE HAD BEEN NO TFC CONFLICT. I MADE AN APOLOGETIC PAX ANNOUNCEMENT ONCE WE WERE THROUGH THE RIDE AND CALLED THE F/O ON THE INTERPHONE TO SEE IF ANYBODY WAS HURT. THANKFULLY, EVERYBODY WAS FINE. I REALIZED ONCE AGAIN THAT RADAR DOESN'T SHOW TURB OR GIVE ALL CLUES TO WHERE IT MIGHT BE OR ITS SEVERITY. CLRLY I WAITED TOO LONG TO PREPARE THE CABIN AND/OR REQUEST A DEVIATION FROM ATC. CONTRIBUTING TO THIS INCIDENT WAS MY MENTAL FATIGUE DUE TO HAVING TAKEN A 6 MONTH CHKRIDE JUST 2 NIGHTS BEFORE AND THEN BEING ASSIGNED THIS TRIP WHICH INCLUDED 13 HRS DUTY AND 8+ HRS OF FLT TIME ON DAY #2--DAY OF THIS EVENT. I WAS, IN THIS CASE, BEHIND THE ACFT A LITTLE, AND UNDERESTIMATED THE WX: COMPLACENCY.

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.