ALTDEV ALT OVERSHOT IN CLB.

Narrative

AFTER TAKING OFF VFR FROM HOT SPRINGS; AR; ENRTE TO HARRISON; AR; WE PICKED UP AN IFR CLRNC OUT OF ABOUT 6000 FT. ZME CLRED US AS FILED TO CLB TO 10000 FT. I WAS THE NFP; SITTING IN THE R SEAT. THE FO; WHO WAS CAPT QUALIFIED AND CHKED OUT AS CAPT WAS FLYING FROM THE L SEAT. (NOT THAT IT MAKE ANY DIFFERENCE). ANYWAY; MEMPHIS TOLD US TO CLB TO 10000 FT; I READ BACK 10000 FT BUT THE FO PUT 11000 FT IN THE ALT WINDOW INADVERTENTLY. PASSING 10000 THE ALT CHIME WENT OFF. I ASKED THE FO 'WEREN'T WE CLRED TO 10000 FT?' HE SAID HE 'THOUGHT IT WAS 11000 FT.' WE LEVELED OFF AT ABOUT 10400 FT AND I WAS GOING TO CALL CTR AND CONFIRM OUR ALT. AT THAT TIME CTR CALLED US AND QUESTIONED OUR ALT. WE WERE DSNDING BACK DOWN TO 10000 FT FROM ABOUT 10500 FT AT ABOUT 10200 FT DSNDING I REPLIED 10000 FT. CTR THEN TOLD US TO GO AHEAD AND CLB TO 12000 FT WHICH WE DID. WE NEVER GOT MUCH HIGHER THAN ABOUT 10400 FT - 10500 FT (INITIALLY). OUR TFC WAS A COMPANY PLANE ABOUT 30 MI AHEAD AT 11000 FT. I GUESS WHAT CAUSED THE PROB WAS THAT I READ BACK 10000 FT BUT I DIDN'T CHK THE ALT WINDOW; OR IF I LOOKED AT IT I DIDN'T NOTICE IT WAS SET AT 11000 FT. USUALLY THE NFP TALKS ON THE RADIO AND SETS THE ALT WINDOW. WHEN CTR TOLD US 10000 FT THE FO'S ARM MOVED UP TO SET THE ALT AND I WASN'T REALLY WATCHING. THIS SORT OF THING ALMOST NEVER HAPPENS. IT SEEMS LIKE WHEN IT DOES THOUGH; IT'S ALWAYS A BEAUTIFUL SUNNY DAY; AS IN THIS CASE.