Narrative:

We were rerouted by ATC due to reports of moderate to severe turbulence on our original route. Flight control had advised us this might happen. We encountered light to moderate during our climb to FL370. FL390 was reported smooth so we asked for and received clearance to FL390. At leveloff the autoplt and autothrottles captured normal cruise. It was smooth. I turned off the seat belt light and went to use the restroom. The copilot was on oxygen and everything was normal. As I returned to the cockpit a short time later, I began to feel some turbulence. I quickly got into my seat and as I did so, I noticed the airspeed was down to approximately 205 KTS and engine #2 throttle was forward while #1 and #3 pulled back. I disconnected the autoplt and autothrottles, pushed forward on the control column and pushed throttles #1 and #3 up while calling for maximum climb. The airplane would not accelerate and had difficulty maintaining altitude. I told the copilot to ask for a lower altitude. He was still wearing his oxygen mask so I couldnþt tell whether or not he was requesting lower. He pulled the mask off and said we are cleared a block altitude of FL390 to FL370. We were FL388 at the time. I dumped the nose slightly and leveled off at FL370 at normal cruise speed. Although we never got below stall speed during the incident, we nevertheless did encounter some slight buffeting due to the high altitude and turbulent environment. We made a turbulence report to center and wrote up the autothrottles. The whole incident could have been avoided if the captain had briefed and warned the crew about the 'notorious' autothrottles on the L1011.

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Original NASA ASRS Text

Title: L1011 ACFT CLBED TO FIND SMOOTH AIR AND AFTER LEVELOFF AUTOTHROTTLES MALFUNCTIONED. #2 THROTTLE WAS FORWARD AND #1 AND #3 WERE PULLED BACK RESULTING IN DETERIORATING AIRSPD. SPD WAS LOW ENOUGH THAT RPTR HAD TO DSND TO GET SPD BACK.

Narrative: WE WERE REROUTED BY ATC DUE TO RPTS OF MODERATE TO SEVERE TURB ON OUR ORIGINAL RTE. FLT CTL HAD ADVISED US THIS MIGHT HAPPEN. WE ENCOUNTERED LIGHT TO MODERATE DURING OUR CLB TO FL370. FL390 WAS RPTED SMOOTH SO WE ASKED FOR AND RECEIVED CLRNC TO FL390. AT LEVELOFF THE AUTOPLT AND AUTOTHROTTLES CAPTURED NORMAL CRUISE. IT WAS SMOOTH. I TURNED OFF THE SEAT BELT LIGHT AND WENT TO USE THE RESTROOM. THE COPLT WAS ON OXYGEN AND EVERYTHING WAS NORMAL. AS I RETURNED TO THE COCKPIT A SHORT TIME LATER, I BEGAN TO FEEL SOME TURB. I QUICKLY GOT INTO MY SEAT AND AS I DID SO, I NOTICED THE AIRSPD WAS DOWN TO APPROX 205 KTS AND ENG #2 THROTTLE WAS FORWARD WHILE #1 AND #3 PULLED BACK. I DISCONNECTED THE AUTOPLT AND AUTOTHROTTLES, PUSHED FORWARD ON THE CTL COLUMN AND PUSHED THROTTLES #1 AND #3 UP WHILE CALLING FOR MAX CLB. THE AIRPLANE WOULD NOT ACCELERATE AND HAD DIFFICULTY MAINTAINING ALT. I TOLD THE COPLT TO ASK FOR A LOWER ALT. HE WAS STILL WEARING HIS OXYGEN MASK SO I COULDNþT TELL WHETHER OR NOT HE WAS REQUESTING LOWER. HE PULLED THE MASK OFF AND SAID WE ARE CLRED A BLOCK ALT OF FL390 TO FL370. WE WERE FL388 AT THE TIME. I DUMPED THE NOSE SLIGHTLY AND LEVELED OFF AT FL370 AT NORMAL CRUISE SPD. ALTHOUGH WE NEVER GOT BELOW STALL SPD DURING THE INCIDENT, WE NEVERTHELESS DID ENCOUNTER SOME SLIGHT BUFFETING DUE TO THE HIGH ALT AND TURBULENT ENVIRONMENT. WE MADE A TURB RPT TO CTR AND WROTE UP THE AUTOTHROTTLES. THE WHOLE INCIDENT COULD HAVE BEEN AVOIDED IF THE CAPT HAD BRIEFED AND WARNED THE CREW ABOUT THE 'NOTORIOUS' AUTOTHROTTLES ON THE L1011.

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.