Narrative:

We encountered wake turbulence climbing thru FL295 up to FL340. When we hit the clear air turbulence the first officer took control of the aircraft and disconnected the autoplt. He then made corrections for an immediate descent to get out of the wake turbulence. I called back on the PA to the flight attendants first to tell them to situation down. It was about 5-10 seconds before I called ATC to tell them we encountered severe turbulence and were descending to a smoother altitude. ATC replied that we were cleared to FL280. The first officer and I agreed to submit a report just in case the descent created a problem with anything else before ATC gave us an altitude clearance. No injuries to passenger; flight attendants or captain's ego. We wrote up the severe turbulence when we landed at our destination. Both the first officer and I were trying to remember if the ATC controller mentioned that the B767 above and upwind to the left was a 'heavy' or not. If traffic and 'heavy' was called out; maybe we would have been more aware of the possibility of wake turbulence? Wake turbulence led to us descending back down thru a previously vacated altitude as we talked with ATC.supplemental information from acn 808269: aircraft was climbing through 29400 ft when a slight burble began just like an oncoming stall. Aircraft was on autopilot with lvl chg mode selected and .74M in the window. Another aircraft was visible in the TCAS approximately 12-15 miles in front and above our flight path. ATC had made no notification of in trail of a heavy aircraft. Following the burble; was an uncommanded roll left 30 degrees followed by 20 degrees right while on autopilot. Moderate to severe turbulence as well. I immediately disengaged the autopilot to initiate a stall recovery and descend the aircraft. Top of climb arc was 29800 ft with more turbulence descending through 29500 ft again. Aircraft was in smooth air below that and recovered at 28000 ft. Notification was then given to ATC of severe turbulence who replied to turn 20 degrees right. Center then informed us that we were in trail of a heavy aircraft from another airline. We then deduced that the event was wake turbulence/accelerated stall caused by being in trail of the heavy aircraft. All engine indications appeared normal and no structural damage was suspected with flight attendants reporting no injuries in the cabin so we continued to our destination. I feel failure of notification and possibly separation from the heavy aircraft could have prevented this from occurring. Beyond that; training took over as I disconnected the autopilot and initiated the stall recovery with the modification of not adding power since it was an accelerated stall. Possibly using this type of scenario in a pt event?

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Original NASA ASRS Text

Title: WAKE TURBULENCE ENCOUNTERED AT FL290 BY A B737 CLBING BEHIND A B767 12 TO 15 MILES AHEAD CAUSING UNCOMMANDED ROLL OF UP TO 30 DEGS L AND R.

Narrative: WE ENCOUNTERED WAKE TURB CLBING THRU FL295 UP TO FL340. WHEN WE HIT THE CLEAR AIR TURB THE FO TOOK CONTROL OF THE ACFT AND DISCONNECTED THE AUTOPLT. HE THEN MADE CORRECTIONS FOR AN IMMEDIATE DSCNT TO GET OUT OF THE WAKE TURB. I CALLED BACK ON THE PA TO THE FLT ATTENDANTS FIRST TO TELL THEM TO SIT DOWN. IT WAS ABOUT 5-10 SECONDS BEFORE I CALLED ATC TO TELL THEM WE ENCOUNTERED SEVERE TURB AND WERE DSNDING TO A SMOOTHER ALTITUDE. ATC REPLIED THAT WE WERE CLEARED TO FL280. THE FO AND I AGREED TO SUBMIT A RPT JUST IN CASE THE DSCNT CREATED A PROBLEM WITH ANYTHING ELSE BEFORE ATC GAVE US AN ALTITUDE CLRNC. NO INJURIES TO PAX; FLT ATTENDANTS OR CAPTAIN'S EGO. WE WROTE UP THE SEVERE TURB WHEN WE LANDED AT OUR DEST. BOTH THE FO AND I WERE TRYING TO REMEMBER IF THE ATC CTLR MENTIONED THAT THE B767 ABOVE AND UPWIND TO THE LEFT WAS A 'HEAVY' OR NOT. IF TFC AND 'HEAVY' WAS CALLED OUT; MAYBE WE WOULD HAVE BEEN MORE AWARE OF THE POSSIBILITY OF WAKE TURB? WAKE TURB LED TO US DSNDING BACK DOWN THRU A PREVIOUSLY VACATED ALTITUDE AS WE TALKED WITH ATC.SUPPLEMENTAL INFO FROM ACN 808269: AIRCRAFT WAS CLIMBING THROUGH 29400 FT WHEN A SLIGHT BURBLE BEGAN JUST LIKE AN ONCOMING STALL. AIRCRAFT WAS ON AUTOPILOT WITH LVL CHG MODE SELECTED AND .74M IN THE WINDOW. ANOTHER AIRCRAFT WAS VISIBLE IN THE TCAS APPROXIMATELY 12-15 MILES IN FRONT AND ABOVE OUR FLIGHT PATH. ATC HAD MADE NO NOTIFICATION OF IN TRAIL OF A HEAVY AIRCRAFT. FOLLOWING THE BURBLE; WAS AN UNCOMMANDED ROLL LEFT 30 DEGREES FOLLOWED BY 20 DEGREES RIGHT WHILE ON AUTOPILOT. MODERATE TO SEVERE TURBULENCE AS WELL. I IMMEDIATELY DISENGAGED THE AUTOPILOT TO INITIATE A STALL RECOVERY AND DESCEND THE AIRCRAFT. TOP OF CLIMB ARC WAS 29800 FT WITH MORE TURBULENCE DESCENDING THROUGH 29500 FT AGAIN. AIRCRAFT WAS IN SMOOTH AIR BELOW THAT AND RECOVERED AT 28000 FT. NOTIFICATION WAS THEN GIVEN TO ATC OF SEVERE TURBULENCE WHO REPLIED TO TURN 20 DEGREES RIGHT. CENTER THEN INFORMED US THAT WE WERE IN TRAIL OF A HEAVY AIRCRAFT FROM ANOTHER AIRLINE. WE THEN DEDUCED THAT THE EVENT WAS WAKE TURBULENCE/ACCELERATED STALL CAUSED BY BEING IN TRAIL OF THE HEAVY AIRCRAFT. ALL ENGINE INDICATIONS APPEARED NORMAL AND NO STRUCTURAL DAMAGE WAS SUSPECTED WITH FLIGHT ATTENDANTS REPORTING NO INJURIES IN THE CABIN SO WE CONTINUED TO OUR DESTINATION. I FEEL FAILURE OF NOTIFICATION AND POSSIBLY SEPARATION FROM THE HEAVY AIRCRAFT COULD HAVE PREVENTED THIS FROM OCCURRING. BEYOND THAT; TRAINING TOOK OVER AS I DISCONNECTED THE AUTOPILOT AND INITIATED THE STALL RECOVERY WITH THE MODIFICATION OF NOT ADDING POWER SINCE IT WAS AN ACCELERATED STALL. POSSIBLY USING THIS TYPE OF SCENARIO IN A PT EVENT?

Data retrieved from NASA's ASRS site as of May 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.