FLYING KORRY 3 STAR TO LGA; INEXPERIENCED AND FATIGUED B737-800 FLT CREW CROSSES RIDGY AT OR ABOVE FL270 AS PUBLISHED VICE AT AND MAINTAIN FL270 AS CLEARED.

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ALL WAS NORMAL ON THE KORRY THREE ARR INTO LGA. ATC ADVISED US TO DSND TO 'CROSS RIDGY INTXN AT AND MAINTAIN FL270.' THE CAPT WAS FLYING AND I WAS THE PNF. BEFORE THE ARR WE HAD VERIFIED ALL THE WAYPOINTS AND ALT INFO IN THE FMC. ALL THE INFO WAS CORRECT AND ACCURATE. WHEN WE WERE GIVEN THE CLRNC; WE AGAIN VERIFIED THE INFO AND IT APPEARED TO BE ACCURATE FOR THE ACFT TO MAKE THE APPROPRIATE XING RESTR AT RIDGY INTXN. THE ONLY PROB HOWEVER WAS THE FIX IN THE FMC STILL HAD THE ORIGINAL ALT INFO FROM THE KORRY THREE ARR. IT HAD US XING AT OR ABOVE FL270. DURING THE FMC VERIFICATION PROCESS WE FAILED TO NOTICE THE '270A' IN THE DISPLAY. HOW THE PROB WAS DISCOVERED: AS WE CROSSED THE RIDGY INTXN WE REALIZED WE WERE AT FL300 DSNDING TO FL270. WE HAD NOT COMPLIED WITH THE CLRNC. THE AUTOPLT WAS ON AND COUPLED WITH THE FMC DURING THE WHOLE EVOLUTION. CONTRIBUTING FACTORS: 1) I BELIEVE FATIGUE MAY HAVE PLAYED A ROLE IN THIS INCIDENT. THIS ARR WAS THE FINAL LEG OF A 2 DAY TRIP. DAY 1 HAD AN XA00 SHOW TIME AT LGA. THE TOTAL BLOCK TIME ON THE TRIP WAS APPROX 14 HRS AND 25 MINS. 2) I BELIEVE ANOTHER FACTOR COULD HAVE BEEN THE DIM LIGHTING ON THE FLT DECK AT THE TIME. THE LIGHTS ON THE FMC AND FLT DECK WERE DIMMED LOW. THIS MAY HAVE CAUSED US TO ONLY SEE THE FL270 SELECTIVELY AND NOT THE FL270A. 3) A THIRD FACTOR THAT MAY HAVE LED TO THIS INCIDENT IS THE LACK OF EXPERIENCE WITH THIS PARTICULAR FMC SYS. THE CAPT HAD 43 HRS IN THE B737-800 AND APPROX 12 HRS AS PIC IN THE AIRPLANE BEFORE THE START OF THE TRIP. I ONLY HAD 280 HRS IN THE ACFT BEFORE THE START OF THE TRIP. CORRECTIVE ACTIONS: 1) CHANGE FMC DEFAULT PROGRAMMING TO MAKE ALL ALTS 'HARD' ALTS. THIS WOULD STILL ALLOW MODIFICATION OF THE ALTS TO AT OR ABOVE; ETC; BUT MAY REDUCE THE INSTANCES OF MISTAKES BEING MADE IN THE FUTURE. 2) CHANGE THE ARR TO HAVE ALL ALTS 'HARD' ALTS. 3) ADDITIONAL FMC TRAINING IN 'DSND VIA' CLRNCS DURING INITIAL AND RECURRENT TRAINING. THE ONLY TRAINING I RECALL RECEIVING ON 'DSND VIA' WAS DURING MY IOE. THIS WOULD HIGHLIGHT SOME OF THE PITFALLS THAT ARE INHERENT THE FMC DATABASE. 4) CHANGE FMC PROGRAMMING TO MAKE THE ALTS AND THE ATTRIBUTES ATTACHED TO THOSE ALTS MORE VISIBLE AND APPARENT. 5) CHANGE CREW REST CYCLES. WE HAD AN EARLY RPT ON DAY 1 AND A LATE LAND TIME ON DAY 2. THESE TIMES ARE IN THE SAME TIME ZONE. SUGGEST MAKING IT REGULATORY TO KEEP CREWS IN THE SAME WAKE SLEEP CYCLE DURING A SINGLE ROTATION. FOR EXAMPLE FLYING MORNINGS OR EVENINGS ONLY. NOT BOTH.