ALTDEV ALT OVERSHOT IN DSCNT.

Narrative

DURING DSCNT AND FROM ENRTE PHASE: ABQ GAVE US A PLT DISCRETION DSCNT FROM FL310 TO FL170. ACFT AND AUTOPLT AND FMS WAS ENGAGED AND DSCNT WAS STARTED 60 NM N OF SANTA TERESA; NM. I RPTED LEAVING FL310 FOR 17000 FT. DURING DSCNT; CTR GAVE ME A 10 DEG L TURN TO AVOID OPPOSITE DIRECTION TFC (KING AIR AT FL190). AT APPROX FL210 I HAD THE FO HAND FLY THE AIRPLANE. THERE WERE NO PAX; AND THE FO NEEDS EXPERIENCE IN THE AIRPLANE. THE ALT PRE-SELECT WAS SET TO 17000 FT. I WAS PREOCCUPIED LOOKING FOR THE TFC POINTOUT; AND DID NOT HEAR THE 1000 FT WARNING BEEP. THE BEEP I HEARD; WAS THE 300 FT LOW BEEP AS WE DSNDED THROUGH 16600 FT. I STOPPED THE DSCNT; AND IMMEDIATELY CLBED BACK TO 17000 FT. ATC ASKED IF I HAD SANTA TERESA ARPT IN SIGHT; AND I REPLIED AFFIRMATIVE. ABQ HANDED US OFF TO EL PASO APCH. I CANCELED OUR IFR AND CONTINUED IN TO SANTA TERESA VFR. THE ALT ALERTER AUDIO IS SOMETIMES MUFFLED BY THE NOISE LEVEL IN THE COCKPIT DUE TO THE SOUND OF GARRET ENGS. THIS ALERT IS FURTHER REDUCED BY THE USE OF HEADSETS. WITHOUT HEADSETS IN THE C441; RADIO PROCS ARE ALMOST IMPOSSIBLE.