Narrative:

Acceleration and clean-up for this departure; consistent with local noise abatement; begins at 3200 ft MSL. Prior to departure; the captain entered a speed restr on the FMC 'climb' page of 180 KTS to 3200 ft. At 3200 ft however; this restr did not delete; and the command speed bug remained at 180 KTS. I advised the captain and adjusted the pitch; accelerated past the 'flaps 5' bug; and called for 'flaps 5.' the command speed bug at some point thereafter moved to 10 KTS below 'min man clean' bug; roughly 235 KTS. I accelerated past 'flaps 1' bug; called for flaps 1; and continued climb and acceleration. As the aircraft approached the 'flaps up' speed; roughly 230 KTS; I noticed that the command bug had not moved to the expected '250 KTS' position but rather had remained in position at roughly 235 KTS. I advised the captain that I would delay the 'flaps up' call until the command bug advanced to a safer speed. Having actually witnessed a captain actuate the stick shaker on a B767 departure only 2 months earlier with flaps retracted; in a turn; and off target in this exact speed regime; I was concerned that the flight director would depict a pitch attitude dangerously close to pitch limit given our weight and speed; if I would have called for 'flaps up.' by now; I was approaching our initial assigned altitude of 6000 ft MSL; and following the flight director pitch decrease; the aircraft naturally accelerated toward 250 KTS. However; during this phase of flight; the command speed bug went to 265 KTS! The throttles advanced in response to the increased command speed. I switched the autothrottles 'off;' glanced again at my airspeed; and realized I had not yet called for 'flaps up.' I gave this call within 2-3 KTS at 250 KTS indicated. My assumption is that before the slats fully retracted; my airspeed went to 260 KTS; owing to the associated thrust increase from the engines just at leveloff; before my autothrottle disconnect. Supplemental information from acn 788664: during climb out with VNAV selected; the airspeed command bug commanded a speed well below the speed required for the actual airspeed and flap confign. Our actual airspeed was above the flaps 0 bug; but the commanded speed was barely above the flaps 1 bug. At this time we had flaps at 1. This lagging airspeed bug was distracting; especially since the altitude-dependent airspeed restrs had already been complied with. We quickly tried to sort out if the command bug was giving us bad information. After we determined that it was safe to retract the flaps; the first officer called for flaps up. As we brought the flaps from 1 to 0 it is possible that we had a minor flap overspeed of 5-10 KTS. After the flaps were up; the airspeed command bug indicated normally. The FMC can take a few seconds to react to airspeed changes; but this lag seemed quite long. Upon arrival I made a write-up regarding the FMC commanded airspeed as well as the possible flap overspeed.

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Original NASA ASRS Text

Title: B767 FLT CREW REPORTS COMMAND SPEED BUG NOT MOVING TO CORRECT SETTINGS IN RELATION TO ALTITUDE AND FLAP SETTINGS DURING CLEANUP AFTER TKOF.

Narrative: ACCELERATION AND CLEAN-UP FOR THIS DEP; CONSISTENT WITH LCL NOISE ABATEMENT; BEGINS AT 3200 FT MSL. PRIOR TO DEP; THE CAPT ENTERED A SPD RESTR ON THE FMC 'CLB' PAGE OF 180 KTS TO 3200 FT. AT 3200 FT HOWEVER; THIS RESTR DID NOT DELETE; AND THE COMMAND SPD BUG REMAINED AT 180 KTS. I ADVISED THE CAPT AND ADJUSTED THE PITCH; ACCELERATED PAST THE 'FLAPS 5' BUG; AND CALLED FOR 'FLAPS 5.' THE COMMAND SPD BUG AT SOME POINT THEREAFTER MOVED TO 10 KTS BELOW 'MIN MAN CLEAN' BUG; ROUGHLY 235 KTS. I ACCELERATED PAST 'FLAPS 1' BUG; CALLED FOR FLAPS 1; AND CONTINUED CLB AND ACCELERATION. AS THE ACFT APCHED THE 'FLAPS UP' SPD; ROUGHLY 230 KTS; I NOTICED THAT THE COMMAND BUG HAD NOT MOVED TO THE EXPECTED '250 KTS' POS BUT RATHER HAD REMAINED IN POS AT ROUGHLY 235 KTS. I ADVISED THE CAPT THAT I WOULD DELAY THE 'FLAPS UP' CALL UNTIL THE COMMAND BUG ADVANCED TO A SAFER SPD. HAVING ACTUALLY WITNESSED A CAPT ACTUATE THE STICK SHAKER ON A B767 DEP ONLY 2 MONTHS EARLIER WITH FLAPS RETRACTED; IN A TURN; AND OFF TARGET IN THIS EXACT SPD REGIME; I WAS CONCERNED THAT THE FLT DIRECTOR WOULD DEPICT A PITCH ATTITUDE DANGEROUSLY CLOSE TO PITCH LIMIT GIVEN OUR WT AND SPD; IF I WOULD HAVE CALLED FOR 'FLAPS UP.' BY NOW; I WAS APCHING OUR INITIAL ASSIGNED ALT OF 6000 FT MSL; AND FOLLOWING THE FLT DIRECTOR PITCH DECREASE; THE ACFT NATURALLY ACCELERATED TOWARD 250 KTS. HOWEVER; DURING THIS PHASE OF FLT; THE COMMAND SPD BUG WENT TO 265 KTS! THE THROTTLES ADVANCED IN RESPONSE TO THE INCREASED COMMAND SPD. I SWITCHED THE AUTOTHROTTLES 'OFF;' GLANCED AGAIN AT MY AIRSPD; AND REALIZED I HAD NOT YET CALLED FOR 'FLAPS UP.' I GAVE THIS CALL WITHIN 2-3 KTS AT 250 KTS INDICATED. MY ASSUMPTION IS THAT BEFORE THE SLATS FULLY RETRACTED; MY AIRSPD WENT TO 260 KTS; OWING TO THE ASSOCIATED THRUST INCREASE FROM THE ENGS JUST AT LEVELOFF; BEFORE MY AUTOTHROTTLE DISCONNECT. SUPPLEMENTAL INFO FROM ACN 788664: DURING CLBOUT WITH VNAV SELECTED; THE AIRSPD COMMAND BUG COMMANDED A SPD WELL BELOW THE SPD REQUIRED FOR THE ACTUAL AIRSPD AND FLAP CONFIGN. OUR ACTUAL AIRSPD WAS ABOVE THE FLAPS 0 BUG; BUT THE COMMANDED SPD WAS BARELY ABOVE THE FLAPS 1 BUG. AT THIS TIME WE HAD FLAPS AT 1. THIS LAGGING AIRSPD BUG WAS DISTRACTING; ESPECIALLY SINCE THE ALT-DEPENDENT AIRSPD RESTRS HAD ALREADY BEEN COMPLIED WITH. WE QUICKLY TRIED TO SORT OUT IF THE COMMAND BUG WAS GIVING US BAD INFO. AFTER WE DETERMINED THAT IT WAS SAFE TO RETRACT THE FLAPS; THE FO CALLED FOR FLAPS UP. AS WE BROUGHT THE FLAPS FROM 1 TO 0 IT IS POSSIBLE THAT WE HAD A MINOR FLAP OVERSPEED OF 5-10 KTS. AFTER THE FLAPS WERE UP; THE AIRSPD COMMAND BUG INDICATED NORMALLY. THE FMC CAN TAKE A FEW SECONDS TO REACT TO AIRSPD CHANGES; BUT THIS LAG SEEMED QUITE LONG. UPON ARR I MADE A WRITE-UP REGARDING THE FMC COMMANDED AIRSPD AS WELL AS THE POSSIBLE FLAP OVERSPEED.

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.