A CLBING A310 OVERSHOOTS ITS ASSIGNED ALT OF 10000 FT. INTERESTING DESIGN FEATURES IN THE AUTOFLT; AUTOTHROTTLE SYS ENTERED INTO THE ALTDEV.

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I WAS FLYING THE DEP WITH FLT DIRECTORS ON. ALT ASSIGNED WAS 10000 FT MSL; BUT ACTUAL LEVELOFF WAS 10300 FT; THEN RETURNED TO 10000 FT MSL. ACFT WAS VERY LIGHT AND CLB RATE WAS VERY HIGH. PASSING THROUGH 7000 FT; RATE OF CLB WAS +3800 FPM. THE ALT AND SPD FMA'S ILLUMINATED AT APPROX 8000 FT MSL. AT 9000 FT MSL THE 1000 FT TO GO CALL WAS MADE BY THE CAPT. AT 9600 FT; APCHING ALT CALL WAS MADE BY CAPT. FLT DIRECTOR BARS WERE CTRED THROUGHOUT THE CLB AND AT 9600 FT I MADE AN AGGRESSIVE ATTEMPT TO LEVEL AT 10000 FT. ALL SOPS FOLLOWED: THE CORRECT ALT WAS SET IN THE WINDOW. BOTH PLTS WERE AWARE OF THE 10000 FT CLRNC AND OUR PROX TO 10000 FT. THIS ACFT HAS A SOFT ALT HOLD FUNCTION +/-100 AND THE AUTOMATION OF THE AIRBUS LIMITS LEVELOFF BY LOAD FACTOR. THE AUTOTHROTTLE HAD NOT BEGUN TO RETARD WHEN WE BEGAN THE LEVELOFF. CLB THRUST SETTING MADE LEVELOFF MORE DIFFICULT. OTHER FACTORS ABOUT THIS ACFT AUTOFLT/AUTOTHROTTLE SYS WHEN LIGHT AND LEVELING OFF AT/BELOW 10000 FT; NORMAL CLB HAS THE AUTOTHROTTLE IN CLB DETENT WITH MAX CLB EPR SETTING; RATE OF CLB IS A FUNCTION OF THE SELECTED SPD. WHEN LIGHT AND 250 KTS THIS WILL CAUSE A VERY HIGH RATE OF CLB. LOWERING THE NOSE TO REDUCE THE CLB RATE WILL CAUSE THE AIRSPD TO BUILD UNLESS A) SPD CAPTURE OF THE AUTOTHROTTLES HAS OCCURRED; OR B) THE AUTOTHROTTLES ARE MANUALLY RETARDED. THIS PROB IS COMPOUNDED WHEN LEVELING AT 10000 FT BECAUSE THE MANAGE SPD INCREASES TO BELOW CLB SPD. THIS COMMANDS A REDUCTION IN PWR FOLLOWED BY AN INCREASE IN PWR TO ACCELERATE TO ECONOMY CLB SPD. THIS COMBINATION OF LIGHT GROSS WT AND LEVELING AT 10000 FT HAS NOT HAPPENED VERY OFTEN IN MY EXPERIENCE. THIS CAN BE CHALLENGING. REASON: PF FAILED TO ANTICIPATE EARLY LEVELOFF (PARTLY DUE TO RELIANCE ON FLT DIRECTOR DATA -- WE DISCUSSED THE NEED TO BACK UP WITH RAW DATA) AND THE PNF FAILING TO ADVOCATE AN AGGRESSIVE LEVELOFF UNTIL IT WAS TOO LATE AND PHYSICALLY IMPOSSIBLE TO LEVEL THE ACFT AT 10000 FT MSL. LESSONS LEARNED: DISCUSSED TECHNIQUES ON HOW TO BEST LEVEL OFF AT 10000 FT WHEN LIGHT. INCLUDED IN THIS DISCUSSION WAS THE POSSIBLE NEED TO MANUALLY TAKE THE THROTTLES OUT OF THE CLB DETENT POS TO OVERRIDE THE AUTOTHROTTLE SYS TO ENSURE THE PWR REDUCED MORE EXPEDITIOUSLY WHEN APCHING AN ASSIGNED ALT.