ALTDEV ALT EXCURSION FROM ASSIGNED.

Narrative

ON A SCHEDULED FAR 121 FLT FROM PIE-TLH; AND ABOUT 30 MI S OF TLH AT 11000 FT; I SPOTTED THE ARPT AND RPTED FIELD IN SIGHT TO TALLAHASSEE APCH. CTLR ACKNOWLEDGED AND CLRED US TO 6000 FT; AND TO PROCEED DIRECT TO THE ARPT FOR A VISUAL TO RWY 11 AFTER DSNDING THROUGH 10000 FT. HE RPTED ANOTHER ACFT AHEAD AT 5000 FT; AND WE SAW HIM ON TCASII. FO (WHO WAS FLYING) AND I DISCUSSED THE TFC AHEAD AND THE CLRNC WE'D BEEN GIVEN; WHICH WE THOUGHT WAS A CLRNC FOR A VISUAL APCH. TO AVOID BEING CAUGHT TOO CLOSE TO THE ARPT WITH EXCESSIVE ALT (TYPICAL ATC HANDLING AT MOST ARPTS WE SERVE); WE DSNDED EXPEDITIOUSLY TO GET BELOW THE 5000 FT TFC. PASSING 4500 FT CTLR ASKED US TO VERIFY OUR ALT; AND WHEN WE TOLD HIM; HE SAID WE HADN'T BEEN CLRED FOR THE APCH YET AND THAT OUR ASSIGNED ALT WAS 6000 FT. I APOLOGIZED FOR MISUNDERSTANDING HIS INSTRUCTIONS AND ASKED IF WE SHOULD RETURN TO 6000 FT. HE SAID NO; CONTINUE TO TLH AND SWITCHED US TO TWR FREQ. UNEVENTFUL LNDG FOLLOWED. FO AND I BOTH THOUGHT HE'D CLRED US FOR THE APCH; AND THEREFORE DSCNT FROM 6000 FT WAS AT OUR DISCRETION. I DON'T RECALL HIS EXACT WORDS; UNFORTUNATELY; BUT BOTH PLTS INVOLVED HAVE BEEN IN THE PROFESSION FOR MORE THAN 25 YRS; WERE WELL RESTED AND ALERT; AND CONSIDER OURSELVES REASONABLY BRIGHT AND VERY CONSCIENTIOUS. I WOULDN'T HAVE EVER DISREGARDED THE ALT ASSIGNMENT IF I HADN'T BELIEVED I'D BEEN CLRED FOR THE APCH; BUT APPARENTLY BOTH OF US (PLTS) WERE MISTAKEN. I'D SURE LIKE TO HEAR THE TAPES. SUPPLEMENTAL INFO FROM ACN 301342: APCH CTL CLRED TO DSND AND AT 10000 FT DIRECT TO ARPT DSND TO 6000 FT. THE FO MISSED THE 6000 FT ALT RESTR DUE TO COMPANY RADIO XMISSION FROM ANOTHER ACFT. (FO MIXER SWITCH NOT TURNED OFF). AT ABOUT 6500 FT APCH CTL CALLED TFC AT 5000 FT. AT 6800 FT ALT ALERT SOUNDED PRIOR TO REACHING 6000 FT. FO ASKED CAPT IF WE WERE CLRED FOR VISUAL APCH. HIS ANSWER WAS 'YES' AND VISUAL APCH WAS CONTINUED. THIS PROB WAS CAUSED BY LACK OF COM IN THE COCKPIT AND BY THE CREW. THE FO AUDIO MIXSWITCH WAS MISTAKENLY TURNED UP WHILE TRYING TO IDENT A MARKER. THE ALT ALERT SHOULD HAVE CAUSED BOTH CREWMEMBERS TO CLARIFY CLRNC WITH APCH CTL. THE CALL OF TFC AT 5000 FT SHOULD HAVE CAUSED ANOTHER CALL. APCH CTL COULD HAVE REMINDED US TO MAINTAIN 6000 FT BUT THIS IS NOT REQUIRED. ANOTHER CAUSE WAS TOO MUCH COMPANY COM AT THE LOWER ALTS. WITH A 2-MAN CREW; IF YOU ARE UNABLE TO CONTACT COMPANY AT THE PROPER TIME (HIGHER ALT); YOU SHOULD LEAVE IT UNTIL YOU GET ON THE GND.