Narrative:

We were assigned a turn from 260 to 220 degrees, an altitude change and an airspeed change all at once. The first officer was flying, the aircraft was on autoplt and the perf system was controling the autoplt. Put this occurrence to preoccupation with flight deck automated gadgets and losing sight of the primary job: flying. We were assigned 250 KTS at 7000'. They slowed us to 210 KTS and the first officer entered the command in perf. A couple of mins later approach slowed us again to 170 KTS. This was with the heading and altitude change above. The confusion occurred when we saw the aircraft still doing nearly 250 KTS! It had not slowed. We entered the altitude change, began descent and were playing the 'what's it doing now' game to determine why it hadn't slowed down as commanded. The first officer forgot to activate heading select so the airplane didn't turn. This made the controller unhappy. I have had many run-INS with the perf system. It's a computer designed to be smooth and efficient--mostly efficient. It has ideas of its own and often puts its own priorities ahead of yours. Time lost trying to decide what it's up to puts us behind the aircraft. I hate perf.

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Original NASA ASRS Text

Title: ACR FLT CREW ASSIGNED HEADING, ALT AND SPEED CHANGE AT SAME TIME. FAILED TO TURN OR SLOW DOWN WHILE PROGRAMMING THE PERF (FMC).

Narrative: WE WERE ASSIGNED A TURN FROM 260 TO 220 DEGS, AN ALT CHANGE AND AN AIRSPD CHANGE ALL AT ONCE. THE F/O WAS FLYING, THE ACFT WAS ON AUTOPLT AND THE PERF SYS WAS CTLING THE AUTOPLT. PUT THIS OCCURRENCE TO PREOCCUPATION WITH FLT DECK AUTOMATED GADGETS AND LOSING SIGHT OF THE PRIMARY JOB: FLYING. WE WERE ASSIGNED 250 KTS AT 7000'. THEY SLOWED US TO 210 KTS AND THE F/O ENTERED THE COMMAND IN PERF. A COUPLE OF MINS LATER APCH SLOWED US AGAIN TO 170 KTS. THIS WAS WITH THE HDG AND ALT CHANGE ABOVE. THE CONFUSION OCCURRED WHEN WE SAW THE ACFT STILL DOING NEARLY 250 KTS! IT HAD NOT SLOWED. WE ENTERED THE ALT CHANGE, BEGAN DSCNT AND WERE PLAYING THE 'WHAT'S IT DOING NOW' GAME TO DETERMINE WHY IT HADN'T SLOWED DOWN AS COMMANDED. THE F/O FORGOT TO ACTIVATE HDG SELECT SO THE AIRPLANE DIDN'T TURN. THIS MADE THE CTLR UNHAPPY. I HAVE HAD MANY RUN-INS WITH THE PERF SYS. IT'S A COMPUTER DESIGNED TO BE SMOOTH AND EFFICIENT--MOSTLY EFFICIENT. IT HAS IDEAS OF ITS OWN AND OFTEN PUTS ITS OWN PRIORITIES AHEAD OF YOURS. TIME LOST TRYING TO DECIDE WHAT IT'S UP TO PUTS US BEHIND THE ACFT. I HATE PERF.

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