FO OF A B737-800 OVERSHOT INTERMEDIATE ASSIGNED ALT DURING DEP BLAMES THE ERROR ON THE ACFT MODEL WAS NOT EQUIPPED WITH AN AURAL WARNING 1000 FT PRIOR TO SELECTED ALT.

Narrative

IMPENDING ALTDEV. ASSIGNED 10000 FT BY ATC. BEGAN TO DEVIATE ON CLBOUT AND RECOVERED BY 10300 FT MSL. I FEEL THIS POTENTIAL DEV IS SERIOUS ENOUGH TO WRITE A NASA RPT FOR 2 REASONS: 1) IT STRESSES THE POTENTIAL PITFALLS ASSOCIATED WITH BEING QUALIFIED IN 2 TYPES OF ACFT. IN OUR FLYING; WE ARE QUALIFIED AND FLY BOTH THE B737-300 AND B737-800 AS A COMMON CATEGORY. THESE ACFT ARE SUBSTANTIALLY DIFFERENT IN THEIR TECHNICAL INTERFACE WITH THE PLT. THE DASH 800; FOR INSTANCE; HAS NO REMINDER FOR APCHING A SELECTED ALT. THE DASH 300; HOWEVER; HAS AN AURAL WARNING 1000 FT PRIOR TO SELECTED ALT. I HAD FLOWN THE DASH 300 FOR 5 CONTINUOUS TRIPS PRIOR TO THIS FLT. WITH VERY LITTLE EXPERIENCE IN THE DASH 800; I BELIEVE I WAS 'GEARED' TOWARDS HEARING THAT WARNING; AND WITHOUT IT ALMOST MISSED LEVELING AT OUR ASSIGNED ALT. 2) DURING THIS FLT WE HAD AN EXTRA PLT OCCUPYING THE COCKPIT JUMP SEAT. WITH 3 PLTS IN THE COCKPIT; THERE WAS SUBSTANTIAL COCKPIT 'CHATTER.' THIS LED TO BOTH MYSELF AND THE CAPT MISSING THE STANDARD 1000 FT PRIOR TO LEVELOFF CALLOUT. THIS INCIDENT MORE THAN EMPHASIZED THE NEED FOR STRICT VIGILANCE TO STERILE COCKPIT PROCS.