Narrative:

During departure on a RNAV departure from atlanta on runway 27R; after 1000 ft MSL; I requested from the first officer: VNAV; climb power; flaps 5 degrees. After a few seconds I armed #1 autoplt on; at which time I noticed that the airspeed indicator window; instead of being close; was locked at 250 KTS. The airspeed bug was stuck at 200 KTS. I continued to accelerate past 210 KTS for flaps up speed. We noticed then that the aircraft did not follow speed commands; navigation commands or anything else. We disconnected the autoplt and recycled the VNAV and LNAV switches; but no change. I advised the first officer to tell controller that we were having trouble with the aircraft. I started hand-flying but we were already to the right of the RNAV departure radials but correcting. After getting some of the automation back I armed #1 autoplt. We were cleared to 10000 ft but aircraft busted the altitude as it did not leveloff and passed altitude by 400-600 ft; at which time I disconnected autoplt again and returned to 10000 ft and reduced speed that went from 240 KTS to 270 KTS. We were very confused and surprised by all that was going on. I then connected the center autoplt and then climbed to 14000 ft as requested. After all this the aircraft started to operate as commanded. We called the company from cruise flight and reported what happened. We were told to pull circuit breakers E-16 and E-17. Aircraft operated normally the rest of the flight. Dispatcher and maintenance coordinator told us not to write anything on logbook. During departure from atlanta the controller told us that we went right off course a certain distance; which I do not recall. We told them that we were having problems with the aircraft navigation system and autoplt. Nothing else was said.

Related reports:

Google
 

Original NASA ASRS Text

Title: B757 FLT CREW RELATES AUTOFLT SYSTEM MALFUNCTIONS THAT RESULT IN TRACK AND ALT DEVIATIONS.

Narrative: DURING DEP ON A RNAV DEP FROM ATLANTA ON RWY 27R; AFTER 1000 FT MSL; I REQUESTED FROM THE FO: VNAV; CLB PWR; FLAPS 5 DEGS. AFTER A FEW SECONDS I ARMED #1 AUTOPLT ON; AT WHICH TIME I NOTICED THAT THE AIRSPD INDICATOR WINDOW; INSTEAD OF BEING CLOSE; WAS LOCKED AT 250 KTS. THE AIRSPD BUG WAS STUCK AT 200 KTS. I CONTINUED TO ACCELERATE PAST 210 KTS FOR FLAPS UP SPD. WE NOTICED THEN THAT THE ACFT DID NOT FOLLOW SPD COMMANDS; NAV COMMANDS OR ANYTHING ELSE. WE DISCONNECTED THE AUTOPLT AND RECYCLED THE VNAV AND LNAV SWITCHES; BUT NO CHANGE. I ADVISED THE FO TO TELL CTLR THAT WE WERE HAVING TROUBLE WITH THE ACFT. I STARTED HAND-FLYING BUT WE WERE ALREADY TO THE R OF THE RNAV DEP RADIALS BUT CORRECTING. AFTER GETTING SOME OF THE AUTOMATION BACK I ARMED #1 AUTOPLT. WE WERE CLRED TO 10000 FT BUT ACFT BUSTED THE ALT AS IT DID NOT LEVELOFF AND PASSED ALT BY 400-600 FT; AT WHICH TIME I DISCONNECTED AUTOPLT AGAIN AND RETURNED TO 10000 FT AND REDUCED SPD THAT WENT FROM 240 KTS TO 270 KTS. WE WERE VERY CONFUSED AND SURPRISED BY ALL THAT WAS GOING ON. I THEN CONNECTED THE CTR AUTOPLT AND THEN CLBED TO 14000 FT AS REQUESTED. AFTER ALL THIS THE ACFT STARTED TO OPERATE AS COMMANDED. WE CALLED THE COMPANY FROM CRUISE FLT AND RPTED WHAT HAPPENED. WE WERE TOLD TO PULL CIRCUIT BREAKERS E-16 AND E-17. ACFT OPERATED NORMALLY THE REST OF THE FLT. DISPATCHER AND MAINT COORDINATOR TOLD US NOT TO WRITE ANYTHING ON LOGBOOK. DURING DEP FROM ATLANTA THE CTLR TOLD US THAT WE WENT R OFF COURSE A CERTAIN DISTANCE; WHICH I DO NOT RECALL. WE TOLD THEM THAT WE WERE HAVING PROBS WITH THE ACFT NAV SYS AND AUTOPLT. NOTHING ELSE WAS SAID.

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