AN EMBRAER 120 FLYING IN ZTL AIRSPACE RECEIVES PLT'S DISCRETION DSCNT TO 11000 FT. THE CAPT WANTS TO REMAIN AT 15000 FT A WHILE LONGER. HE DEPRESSES THE CLB BUTTON THINKING THE ACFT WOULD CLB ONLY 200 FT BACK TO 15000 FT. HOWEVER; HE DIDN'T CHK ALL THE OTHER INST SETTINGS; SO THE ACFT WAS ALLOWED TO CLB TO 16000 FT.

Narrative

LEVEL AT 15000 FT; ZTL CLRED US PLT'S DISCRETION TO 11000 FT AND GAVE US THE NEW ALTIMETER SETTING. THE FO SET 11000 FT IN THE ALT SELECT WINDOW. WHEN I PUT THE NEW ALTIMETER SETTING IN THE KOLSMAN WINDOW; I NOTICED WE WERE AT 14800 FT. I WANTED TO STAY AT 15000 FT LONGER DUE TO CLOUD TOPS; SO WITH THE AUTOPLT ENGAGED; I HIT THE 'CLB' MODE; EXPECTING IT TO CLB TO 15000 FT. WITH 11000 FT IN THE ALT SELECT WINDOW; THE AUTOPLT JUST CONTINUED CLBING. AT THE TIME I HIT THE CLB MODE; THE FLT ATTENDANT CAME TO THE COCKPIT TO SEE IF WE NEEDED ANYTHING. AFTER THIS DISTR; THE FO CAUGHT US CLBING THROUGH 16000 FT. WE IMMEDIATELY DSNDED BACK TO 15000 FT. 7 HRS (7 YRS ALSO ON PREVIOUS DAY) OF IMC FLYING WITH MULTIPLE APCHS; 2 14-HR DUTY DAYS WITH A REDUCED REST THE PREVIOUS NIGHT; 3 ACFT SWAPS BTWN EACH OF THE 3 ROUND-TRIPS; PLUS NO BREAKS FOR FOOD WITH 1+ HRS OF TIME SPENT ON PHONE TO CREW SCHEDULING FOR CHANGES; CONTRIBUTED TO FATIGUE. SUPPLEMENTAL INFO FROM ACN 394380: AT THAT TIME THE FLT ATTENDANT CAME TO COCKPIT. I WAS LOOKING AT HER WHEN CAPT SELECTED 'CLB' MODE ON AUTOPLT TO GO UP TO 15000 FT. SOON I NOTICED A NOSE HIGH ALT AND LOOKED AT THE ALTIMETER TO SEE US GOING THROUGH 16000 FT. I IMMEDIATELY TOLD THE CAPT; HE DISENGAGED THE AUTOPLT AND DSNDED TO 15000 FT. THE FACTORS INVOLVED WERE FATIGUE AND DISTRS. I HAD BEEN ON DUTY 12 HRS AT THE TIME AND THE CAPT WAS TIRED ALSO. THE DISTR OF THE FLT ATTENDANT ALSO CONTRIBUTED.