Narrative:

On takeoff climb out of pdx, MD11 was flown manually. Briefing to PNF was to control glareshield control panel and FMS inputs. Aircraft clean speed was 274 KTS. At 1100 ft, I called for proof, and noticed that aircraft felt mushy. Airspeed had an FMC computed 185 KTS on the indicator and relief pilot advised us that throttles had come back toward idle. At 1500 ft, I heard takeoff warning horn indicating further throttle reduction. All attempts to reprogram airspeed failed, including changing autoplts. Aircraft mushed, descended 200-300 ft at 185 KTS. I disconnected the automatic throttles, pushed them to climb power, continued a climb profile, re- engaged FMS speed manually, re-engaged autoplt and climb continued normally. At this time, we were asked by departure control if we were able to maintain a normal climb profile. We replied 'affirmative' and at this time manual climb resumed. In climb phase, FMC 'computed' airspeed did not get above V2 plus 10. This might have been due to the fact that I selected prof mode in error, but above 1500 ft, I did not see 'climb limit thrust' annunciated on ead. Both first officer and I tried resetting FMS speed, tried to engage flight level change and change autoplts to no avail. The computed airspeed didn't move from 185 KTS. During flight and approach to destination, automatic throttles appeared sluggish and in some cases airspeed computations were incorrect. I wrote a simple note in logbook describing this situation, and briefed outgoing crew. I feel that the FMC's are sending incorrect information to the automatic throttles, but more research needs to be done and documented on this aircraft.

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Original NASA ASRS Text

Title: AN MD-11 CREW HAD PROBS WITH ITS SPD CTL AFTER TKOF.

Narrative: ON TKOF CLB OUT OF PDX, MD11 WAS FLOWN MANUALLY. BRIEFING TO PNF WAS TO CTL GLARESHIELD CTL PANEL AND FMS INPUTS. ACFT CLEAN SPD WAS 274 KTS. AT 1100 FT, I CALLED FOR PROOF, AND NOTICED THAT ACFT FELT MUSHY. AIRSPD HAD AN FMC COMPUTED 185 KTS ON THE INDICATOR AND RELIEF PLT ADVISED US THAT THROTTLES HAD COME BACK TOWARD IDLE. AT 1500 FT, I HEARD TKOF WARNING HORN INDICATING FURTHER THROTTLE REDUCTION. ALL ATTEMPTS TO REPROGRAM AIRSPD FAILED, INCLUDING CHANGING AUTOPLTS. ACFT MUSHED, DSNDED 200-300 FT AT 185 KTS. I DISCONNECTED THE AUTO THROTTLES, PUSHED THEM TO CLB PWR, CONTINUED A CLB PROFILE, RE- ENGAGED FMS SPD MANUALLY, RE-ENGAGED AUTOPLT AND CLB CONTINUED NORMALLY. AT THIS TIME, WE WERE ASKED BY DEP CTL IF WE WERE ABLE TO MAINTAIN A NORMAL CLB PROFILE. WE REPLIED 'AFFIRMATIVE' AND AT THIS TIME MANUAL CLB RESUMED. IN CLB PHASE, FMC 'COMPUTED' AIRSPD DID NOT GET ABOVE V2 PLUS 10. THIS MIGHT HAVE BEEN DUE TO THE FACT THAT I SELECTED PROF MODE IN ERROR, BUT ABOVE 1500 FT, I DID NOT SEE 'CLB LIMIT THRUST' ANNUNCIATED ON EAD. BOTH FO AND I TRIED RESETTING FMS SPD, TRIED TO ENGAGE FLT LEVEL CHANGE AND CHANGE AUTOPLTS TO NO AVAIL. THE COMPUTED AIRSPD DIDN'T MOVE FROM 185 KTS. DURING FLT AND APCH TO DEST, AUTO THROTTLES APPEARED SLUGGISH AND IN SOME CASES AIRSPD COMPUTATIONS WERE INCORRECT. I WROTE A SIMPLE NOTE IN LOGBOOK DESCRIBING THIS SIT, AND BRIEFED OUTGOING CREW. I FEEL THAT THE FMC'S ARE SENDING INCORRECT INFO TO THE AUTO THROTTLES, BUT MORE RESEARCH NEEDS TO BE DONE AND DOCUMENTED ON THIS ACFT.

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.