FLC OF ADVANCED WDB FAILED TO PROGRAM FMC FOR DSCNT; ACFT CONTINUED CLB.

Narrative

WE WERE RAPIDLY CLBING (2500 FPM) THROUGH FL290 WHEN WE HAD BEEN CLRED TO FL310. WE DECIDED TO GO BACK DOWN TO FL280 TO TAKE ADVANTAGE OF LIGHTER HEADWINDS. THE CAPT WAS FLYING AND I SET OUR NEW CLRED ALT OF 28000 IN THE ALT WINDOW. THE CAPT ASSUMED THE PLANE WOULD NOW DSND TO THAT ALT; BUT INSTEAD IT CONTINUED TO CLB BECAUSE WE HAD NOT REPROGRAMMED THE FMC. WITH THE AUTOPLT STILL ENGAGED THE ACFT CONTINUED TO CLB AND EVENTUALLY LEVELED AT FL315 WITH ATC ASKING WHAT OUR ALT WAS. WE THEN DSNDED UNEVENTFULLY BACK TO OUR CLRED ALT OF FL280. OBVIOUSLY THIS INCIDENT WAS CAUSED BY AN OVER RELIANCE IN AUTOMATION. ALL THIS COMPUTER CRAP IS WONDERFUL -- BUT IT STILL TAKES YOU 'OUT OF THE LOOP' AND YOU ASSUME ALL IS WELL. MY SOLUTION ON MY LEGS THAT I FLY IS TO HAND FLY THE ACFT FROM TKOF TO CRUISE ALT LEVEL OFF AND THEN BACK DOWN AGAIN. I ONLY USE THE AUTOPLT IN CRUISE UNLESS I AM TIRED. I AM A 'COMPUTER NUT' AND I LOVE THE AUTOMATION -- BUT I CAN STILL FLY A HELL OF A LOT SMOOTHER AND I CAN ANTICIPATE. THE COMPUTER HAS MANY SHORTCOMINGS; BUT WE ARE TAUGHT TO FLY BY COMPUTER. THIS PRACTICE IS DANGEROUS AND POORLY THOUGHT OUT. THANKS FOR YOUR EXCELLENT CALLBACK PUBLICATION AND A GREAT SYS TO HELP ALL PLTS.