Narrative:

While climbing from FL310 to FL350, weight of aircraft approximately 214000 pounds, aircraft started to descend at FL340. Aircraft on autoplt at time. Rate of descent increased rapidly. Autoplt turned off and aircraft flown manually. Speed of aircraft at the time was mach .790 per ATC. Severe pitch oscillations soon followed in descent. Aircraft at times uncontrollable. Speed ranged from 340 KTS to 230 KTS. Aircraft shook violently while pitching up and down. After briefly stabilizing the aircraft for a few mins in FL240 range, oscillations and violent pitching up and down resumed. Only pitch axis was affected. Roll and lateral control normal at all times throughout flight. During 20 mins from onset to touchdown in srq, at least 4 sets of severe oscillations and turbulence occurred, even as low as 11000 ft and 270 KTS. Severe up and down pitching lasted several mins throughout each episode of uncontrollable flight. Flight attendants in aft galley remarked that the noise from aircraft shaking was deafening. Food and beverage carts shook so hard that they came loose from their stations. Check airman deadheading in first class noted a severe flutter felt throughout duration. No stall warning, stick shaker, or overspd announcements occurred. Engines normal in all power ranges. Majority of time flight in VMC conditions. Aircraft shook so violently both pilots lost headsets and captain's sunglasses came off. At lower airspeed and on approach aircraft flew normally. Landing uneventful. Suspect a possible problem with aircraft pitch mode flight. Callback conversation with reporter revealed the following information: reporter captain was very frustrated that neither his company nor boeing are taking the event as seriously as warranted. They do have an ongoing investigation and boeing is supposed to release their conclusions shortly. Included in boeing's investigation is a clear air turbulence/aircraft position model because they believe the upset was caused by turbulence. The captain, while agreeing they encountered severe turbulence, believes the main cause was elevator malfunction. The DFDR showed a 5 unit split at the worst oscillation showing that the elevators were not in sync. Reporter suspects the elevator PCU (power control unit) which, if malfunctioning may be due to one or more valves stuck in position. A deadheading check airman said the aircraft was 'fluttering' during the upset. Captain had cuts on his legs which he suspects were caused by tucking his legs back under the seat trying to remain in his seat during the oscillations. An emergency was declared and the ground fire crew met the airplane after landing. 4 passenger were taken to the hospital and all the flight attendants complained of injuries. As far as reporter knows none of the injuries were serious. 1 male passenger was so traumatized he couldn't get out of his seat to deplane at the gate. The WX was VMC throughout. When the flight crew descended to a lower altitude and slowed the aircraft it became controllable and operated normally. Reporter says the speed was a factor which, with uncommanded elevator movement, would make sense -- the faster the speed the greater the pitch.

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Original NASA ASRS Text

Title: B757 ACFT IN CLB AT 34000 FT EXPERIENCED SEVERE PITCH OSCILLATIONS RESULTING IN EXCESSIVE G LOADS AND INJURIES. RPTR CAPT ATTRIBUTES THE UPSET TO FAULTY ELEVATOR INPUTS, POSSIBLY THE PCU (PWR CTL UNIT). NO INDICATIONS ON THE EICAS (ENG INDICATION AND CREW ALERTING SYS).

Narrative: WHILE CLBING FROM FL310 TO FL350, WT OF ACFT APPROX 214000 LBS, ACFT STARTED TO DSND AT FL340. ACFT ON AUTOPLT AT TIME. RATE OF DSCNT INCREASED RAPIDLY. AUTOPLT TURNED OFF AND ACFT FLOWN MANUALLY. SPD OF ACFT AT THE TIME WAS MACH .790 PER ATC. SEVERE PITCH OSCILLATIONS SOON FOLLOWED IN DSCNT. ACFT AT TIMES UNCONTROLLABLE. SPD RANGED FROM 340 KTS TO 230 KTS. ACFT SHOOK VIOLENTLY WHILE PITCHING UP AND DOWN. AFTER BRIEFLY STABILIZING THE ACFT FOR A FEW MINS IN FL240 RANGE, OSCILLATIONS AND VIOLENT PITCHING UP AND DOWN RESUMED. ONLY PITCH AXIS WAS AFFECTED. ROLL AND LATERAL CTL NORMAL AT ALL TIMES THROUGHOUT FLT. DURING 20 MINS FROM ONSET TO TOUCHDOWN IN SRQ, AT LEAST 4 SETS OF SEVERE OSCILLATIONS AND TURB OCCURRED, EVEN AS LOW AS 11000 FT AND 270 KTS. SEVERE UP AND DOWN PITCHING LASTED SEVERAL MINS THROUGHOUT EACH EPISODE OF UNCONTROLLABLE FLT. FLT ATTENDANTS IN AFT GALLEY REMARKED THAT THE NOISE FROM ACFT SHAKING WAS DEAFENING. FOOD AND BEVERAGE CARTS SHOOK SO HARD THAT THEY CAME LOOSE FROM THEIR STATIONS. CHK AIRMAN DEADHEADING IN FIRST CLASS NOTED A SEVERE FLUTTER FELT THROUGHOUT DURATION. NO STALL WARNING, STICK SHAKER, OR OVERSPD ANNOUNCEMENTS OCCURRED. ENGS NORMAL IN ALL PWR RANGES. MAJORITY OF TIME FLT IN VMC CONDITIONS. ACFT SHOOK SO VIOLENTLY BOTH PLTS LOST HEADSETS AND CAPT'S SUNGLASSES CAME OFF. AT LOWER AIRSPD AND ON APCH ACFT FLEW NORMALLY. LNDG UNEVENTFUL. SUSPECT A POSSIBLE PROB WITH ACFT PITCH MODE FLT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR CAPT WAS VERY FRUSTRATED THAT NEITHER HIS COMPANY NOR BOEING ARE TAKING THE EVENT AS SERIOUSLY AS WARRANTED. THEY DO HAVE AN ONGOING INVESTIGATION AND BOEING IS SUPPOSED TO RELEASE THEIR CONCLUSIONS SHORTLY. INCLUDED IN BOEING'S INVESTIGATION IS A CLR AIR TURB/ACFT POS MODEL BECAUSE THEY BELIEVE THE UPSET WAS CAUSED BY TURB. THE CAPT, WHILE AGREEING THEY ENCOUNTERED SEVERE TURB, BELIEVES THE MAIN CAUSE WAS ELEVATOR MALFUNCTION. THE DFDR SHOWED A 5 UNIT SPLIT AT THE WORST OSCILLATION SHOWING THAT THE ELEVATORS WERE NOT IN SYNC. RPTR SUSPECTS THE ELEVATOR PCU (PWR CTL UNIT) WHICH, IF MALFUNCTIONING MAY BE DUE TO ONE OR MORE VALVES STUCK IN POS. A DEADHEADING CHK AIRMAN SAID THE ACFT WAS 'FLUTTERING' DURING THE UPSET. CAPT HAD CUTS ON HIS LEGS WHICH HE SUSPECTS WERE CAUSED BY TUCKING HIS LEGS BACK UNDER THE SEAT TRYING TO REMAIN IN HIS SEAT DURING THE OSCILLATIONS. AN EMER WAS DECLARED AND THE GND FIRE CREW MET THE AIRPLANE AFTER LNDG. 4 PAX WERE TAKEN TO THE HOSPITAL AND ALL THE FLT ATTENDANTS COMPLAINED OF INJURIES. AS FAR AS RPTR KNOWS NONE OF THE INJURIES WERE SERIOUS. 1 MALE PAX WAS SO TRAUMATIZED HE COULDN'T GET OUT OF HIS SEAT TO DEPLANE AT THE GATE. THE WX WAS VMC THROUGHOUT. WHEN THE FLC DSNDED TO A LOWER ALT AND SLOWED THE ACFT IT BECAME CONTROLLABLE AND OPERATED NORMALLY. RPTR SAYS THE SPD WAS A FACTOR WHICH, WITH UNCOMMANDED ELEVATOR MOVEMENT, WOULD MAKE SENSE -- THE FASTER THE SPD THE GREATER THE PITCH.

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.