Narrative:

On the chins 5 arrival into seattle at FL200, we were 'cleared to descend via the chins 5 arrival.' I then set 12000 ft into the altitude window for the VNAV descent. Noting that the aircraft was not responding adequately at the top of descent point (reacting slowly) I selected flight level change to begin the descent thereby dropping out of VNAV. I did this believing we would not make the crossing restr of 16000 ft, 280 KTS at the raddy intersection. We began the descent checklist at this time. Seattle was landing south at this time. During descent, I noted the 12000 ft restr noted at raddy intersection for aircraft landing to the north. This is where the problem occurred. Had I stayed in VNAV, the aircraft would have leveled off at 16000 ft since, prior to the arrival, we confirmed all crossing restr were correctly set in the FMS. Being in flight level change, however, allowed to descend to 12000 ft which was the altitude set in the altitude window. The confusion arose when I mistakenly noted 12000 ft as a crossing restr for aircraft landing north rather than 16000 ft for aircraft landing south. After advising us of the deviation, ZSE cleared us to 12000 ft. There were no traffic conflicts or terrain conflicts during this deviation. To help avoid this problem, it would be helpful if crossing restrs for the same intersection for north or south operations were noted in 2 different boxes on the arrival chart, not in the same box. Also, if 'landing north' and 'landing south' were noted in bold face, this would be helpful. Other factors contributing would be distraction (ie, checklists) turbulence, and pilot fatigue (long duty day, late at night body time). Better chart notations and better situational awareness would help prevent this from recurring.

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Original NASA ASRS Text

Title: FLT CREW OF LGT MISTAKENLY SET 12000 FT VICE 16000 FT IN ALT ALERT WINDOW WHILE ON CHINS ARR TO SEA FOR A S LNDG. DSNDED THROUGH ALT RESTR AT RADDY INTXN.

Narrative: ON THE CHINS 5 ARR INTO SEATTLE AT FL200, WE WERE 'CLRED TO DSND VIA THE CHINS 5 ARR.' I THEN SET 12000 FT INTO THE ALT WINDOW FOR THE VNAV DSCNT. NOTING THAT THE ACFT WAS NOT RESPONDING ADEQUATELY AT THE TOP OF DSCNT POINT (REACTING SLOWLY) I SELECTED FLT LEVEL CHANGE TO BEGIN THE DSCNT THEREBY DROPPING OUT OF VNAV. I DID THIS BELIEVING WE WOULD NOT MAKE THE XING RESTR OF 16000 FT, 280 KTS AT THE RADDY INTXN. WE BEGAN THE DSCNT CHKLIST AT THIS TIME. SEATTLE WAS LNDG S AT THIS TIME. DURING DSCNT, I NOTED THE 12000 FT RESTR NOTED AT RADDY INTXN FOR ACFT LNDG TO THE N. THIS IS WHERE THE PROB OCCURRED. HAD I STAYED IN VNAV, THE ACFT WOULD HAVE LEVELED OFF AT 16000 FT SINCE, PRIOR TO THE ARR, WE CONFIRMED ALL XING RESTR WERE CORRECTLY SET IN THE FMS. BEING IN FLT LEVEL CHANGE, HOWEVER, ALLOWED TO DSND TO 12000 FT WHICH WAS THE ALT SET IN THE ALT WINDOW. THE CONFUSION AROSE WHEN I MISTAKENLY NOTED 12000 FT AS A XING RESTR FOR ACFT LNDG N RATHER THAN 16000 FT FOR ACFT LNDG S. AFTER ADVISING US OF THE DEV, ZSE CLRED US TO 12000 FT. THERE WERE NO TFC CONFLICTS OR TERRAIN CONFLICTS DURING THIS DEV. TO HELP AVOID THIS PROB, IT WOULD BE HELPFUL IF XING RESTRS FOR THE SAME INTXN FOR N OR S OPS WERE NOTED IN 2 DIFFERENT BOXES ON THE ARR CHART, NOT IN THE SAME BOX. ALSO, IF 'LNDG N' AND 'LNDG S' WERE NOTED IN BOLD FACE, THIS WOULD BE HELPFUL. OTHER FACTORS CONTRIBUTING WOULD BE DISTR (IE, CHKLISTS) TURB, AND PLT FATIGUE (LONG DUTY DAY, LATE AT NIGHT BODY TIME). BETTER CHART NOTATIONS AND BETTER SITUATIONAL AWARENESS WOULD HELP PREVENT THIS FROM RECURRING.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.