DC9-30 CREW HAD AN ALTDEV IN ZMA CLASS A AIRSPACE.

Narrative

WHILE ON THE LLAK3 ARR TO PBI; ZMA CLRED US TO FL240 THEN TO FL250. 80 MI S OF CTY; WE INFORMED ZMA THAT WE COULD NOT RECEIVE GNV VOR. MIA GAVE US A HDG OF 170 DEGS. ZMA THEN AID 'ACFT X; FLY 170 FOR LLAKE. CLRED LLAK3 ARR.' I HAD READ THE LLAK3 ARR TWICE; BEFORE THE CTR CLRNC. THE ARR PAGE WAS PLACED ON THE YOKE CLIPBOARD IN FRONT OF ME. APPARENTLY; I MISREAD THE ARR. I WAS THINKING THAT THE 10000 FT XING WAS AT LLAKE RATHER THAN AT ULLMN INTXN. I ALSO MISREAD THE 'EXPECT CLRNC' AS A CLRNC TO CROSS AT 10000 FT. WE WERE HIGH ON THE DSCNT PROFILE DUE TO THE UNKNOWN WBOUND TFC AT FL240. WHEN I HEARD THE LLAKE 3 ARR CLRNC; I STARTED MY DSCNT WITHOUT LOOKING AT THE ALT ALERTER. I STOPPED MY DSCNT AT FL244. THE FO NOTICED MY MISTAKE ALONG WITH THE ALERTER BEEPING AND I RETURNED TO FL250. MIA THEN POINTED OUT OUR TFC AT FL240; 1:30 O'CLOCK POS; 1 1/2 MI. I DON'T KNOW WHAT I WAS THINKING. I HAD IT SET IN MY MIND TO START DOWN -- ALWAYS. PNF: SET THE ALTER; PF: POINT THE FINGER; PF: PUSH THE YOKE. SUPPLEMENTAL INFO FROM ACN 574725: MAY HAVE STILL HAD FL240 'ON THE BRAIN' EVEN AFTER ATC AMENDED THAT DSCNT CLRNC TO FL250 ALMOST SIMULTANEOUSLY WITH THE VECTOR TO INTERCEPT THE LLAKES ARR. CLASSIC SET-UP!