AN LJ25 CREW; DSNDING INTO TPA; OVERSHOT THEIR ASSIGNED ALT.

Narrative

WHILE DSNDING FOR LNDG; WE HAD AN ALT INCURSION. I WAS THE FO AND THE PF WHILE THE CAPT WAS HANDLING THE RADIOS AND CHKLISTS. WE HAD RECEIVED SEVERAL STEP-DOWNS AND DURING THESE THE CAPT WAS OCCUPIED TALKING TO THE MEDICAL CREW IN THE CABIN; RUNNING CHKLISTS; FINISHING FINAL PAPERWORK; AND COMMUNICATING WITH ATC. DURING THE COURSE OF THE DSCNT WE ALTERNATED IN SETTING THE ALT ALERTER BECAUSE THE CAPT'S HANDS WERE LITERALLY FULL AT TIMES AND ALSO BECAUSE IT WAS ON THE R SIDE OF THE COCKPIT. WHILE DSNDING TO 13000 FT WE GOT A CLRNC TO 12000 FT; THE CAPT ACKNOWLEDGED ATC; AND NO ONE SET THE ALERTER TO THE NEW ALT (PRESUMABLY EACH ASSUMING THE OTHER WOULD SET IT). I THOUGHT I HEARD 11000 FT AND CONTINUED DOWN TO THAT ALT WHEN SIMULTANEOUSLY THE CAPT AND ATC INFORMED ME OF THE 12000 FT CLRNC. ATC INFORMED US THAT NO CORRECTIVE ACTION WAS NECESSARY AND WE CONTINUED THE DSCNT TO A NORMAL LNDG. THE PROB WAS CAUSED BY MY FAILURE TO UNDERSTAND AND VERIFY THE CORRECT ALT. I BELIEVE STANDARDIZED ALT ALERTER PROCS SHOULD BE USED IN ANY MULTI-MEMBER CREWED ACFT. THE PNF SHOULD ACKNOWLEDGE THE CLRNC TO ATC; SET THE ALERTER; POINT TO THE ALERTER AND VERBALIZE THE NEW ALT TO THE PF; AND THE PF SHOULD POINT TO THE ALERTER AND REPEAT ALOUD THE NEW ALT. THIS WAS A FAILURE OF BASIC CRM. I THINK PART 135 OPERATORS NEED TO EMPHASIZE BASIC CRM AND DEFINED DUTIES FOR FLYING AND PNF'S MORE. I ALSO THINK A STANDARDIZED LOCATION OF THE ALERTER IN THE CTR OF THE COCKPIT MIGHT ELIMINATE SOME OF THE INCLINATION OF THE CLOSER PLT TO 'HELP' THE OTHER GUY BY SETTING IT. SUPPLEMENTAL INFO FROM ACN 539481: WE WERE VERY SOON THEREAFTER CLRED TO 12000 FT. I AM NOT SURE WHO ANSWERED THIS CALL AS I HAD PREOCCUPIED MYSELF WITH OTHER THINGS. WHEN I LOOKED FORWARD WE WERE LEVELING AT 11000 FT AND ALT PRESELECT WAS SET AT 13000 FT. ABOUT THE SAME TIME I QUERIED THE FO; TAMPA QUERIED US ABOUT OUR ALT. I TOLD TAMPA WE WERE AT 11000 FT. THEN ANOTHER ACFT CALLED US IN SIGHT. TAMPA TOLD US WE SHOULD BE AT 12000 FT. I APOLOGIZED AND HE ANSWERED NOT TO WORRY; THAT IT DIDN'T CAUSE A PROB. I DISTRACTED MYSELF FROM MY DUTIES BY TAKING A PICTURE AND IN THE PROCESS DISTRACTED THE REST OF THE CREW ALSO.