B767-300 FO MISUSES THE AUTOPLT FOR A DSCNT PROC AND AIRSPD RESTR DURING THE CIVET STAR ARR PROC; RESULTING IN A SPD DEV.

Narrative

INITIALLY WE WERE ASSIGNED A SPD OF 320 KTS OR GREATER UNTIL ADVISED. AT 5-7 MI PRIOR TO THE ARNES INTXN WE WERE ADVISED TO CROSS ARNES AT 250 KTS. THE AUTOPLT WAS IN THE VNAV MODE AND PROGRAMMED FOR ARNES AT 245 KTS. SPD BRAKES WERE USED TO SLOW THE ACFT. SHORTLY THEREAFTER WE WERE CLRED FOR THE ILS RWY 25L APCH. THROUGH HABIT I ENGAGED THE 'APCH' MODE OF THE AUTOPLT ON RECEIVING THAT CALL. THAT ENGAGED THE SPD AT THE EXISTING SPD OF ABOUT 280 KTS. I THEN REALIZED I STILL NEEDED THE AUTOPLT IN VNAV FOR THE STEPDOWN FIXES ON THE APCH. SINCE THE AUTOPLT HAD ALREADY ENGAGED IN THE APCH MODE; I HAD TO DISENGAGE THE AUTOPLT AND BOTH FLT DIRECTORS BEFORE RE-ENGAGING IN VNAV. THROUGH ALL OF THIS; WE CONTINUED OUR DSCNT TOWARD THE NEXT FIX; SUZZI; AT 9000 FT. ONCE THE AUTOPLT WAS RE- ENGAGED IN VNAV; I NOTICED THE AIRSPD ABOUT 280 KTS. WE SLOWED TO 250 KTS RESULTING IN 1-2 MINS BELOW 10000 FT ABOVE 250 KTS. DURING THIS BRIEF PERIOD THE CAPT WAS BUSY IDENTING THE ILS FREQ AND STARTING THE APCH CHKLIST.