Narrative:

As flight leveled off at cruise altitude FL290, captain programmed arrival routing into FMC while first officer flew aircraft. Flight crossed STAR intersection #1 at FL240 and was then cleared to FL230. On the arrival flight encountered moderate clear air turbulence at FL230 and first officer went off primary ATC radio frequency to make PA to passenger, with captain assuming control of aircraft and clearance to FL220, cross whigg intersection at 11000 ft. Descent to FL220 was initiated and aircraft leveled at FL220, with altitude alerter set at 11000 ft. Turbulence avoidance became primary focus of aircrew and FMC computer was not updated with 11000 ft altitude restr at whigg (FMC descent profile was computed to arrive at las field only). Upon completion of PA, first officer assumed control of aircraft and captain left primary ATC frequency to coordinate turbulence actions with flight attendants and passenger. First officer followed FMC-programmed descent profile and approximately 5 mi from whigg intersection controller asked if flight would be able to comply with the associated altitude restr. Aircraft was not able to descend to meet restr and was vectored away from arrival corridor and instructed to maintain altitude for opposite direction traffic to pass by. Aircrew complied with revised instructions and was subsequently reclred for arrival into las with no further complications. This seems like a human performance and communication failure between the pilots flying with assumption by first officer that both arrival routing and altitude restrs were entered into FMC when this was not the case. Turbulence issues distracted aircrew from backing each other up.

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Original NASA ASRS Text

Title: FLC OF AN MLG UNDERSHOT DSCNT ALT DURING A STAR ARR CAUSING ATC TO INTERVENE AND TURN THEM OFF COURSE IN ORDER TO PROVIDE THE APPROPRIATE SEPARATION OF OPPOSITE DIRECTION TFC.

Narrative: AS FLT LEVELED OFF AT CRUISE ALT FL290, CAPT PROGRAMMED ARR ROUTING INTO FMC WHILE FO FLEW ACFT. FLT CROSSED STAR INTXN #1 AT FL240 AND WAS THEN CLRED TO FL230. ON THE ARR FLT ENCOUNTERED MODERATE CLR AIR TURB AT FL230 AND FO WENT OFF PRIMARY ATC RADIO FREQ TO MAKE PA TO PAX, WITH CAPT ASSUMING CTL OF ACFT AND CLRNC TO FL220, CROSS WHIGG INTXN AT 11000 FT. DSCNT TO FL220 WAS INITIATED AND ACFT LEVELED AT FL220, WITH ALT ALERTER SET AT 11000 FT. TURB AVOIDANCE BECAME PRIMARY FOCUS OF AIRCREW AND FMC COMPUTER WAS NOT UPDATED WITH 11000 FT ALT RESTR AT WHIGG (FMC DSCNT PROFILE WAS COMPUTED TO ARRIVE AT LAS FIELD ONLY). UPON COMPLETION OF PA, FO ASSUMED CTL OF ACFT AND CAPT LEFT PRIMARY ATC FREQ TO COORDINATE TURB ACTIONS WITH FLT ATTENDANTS AND PAX. FO FOLLOWED FMC-PROGRAMMED DSCNT PROFILE AND APPROX 5 MI FROM WHIGG INTXN CTLR ASKED IF FLT WOULD BE ABLE TO COMPLY WITH THE ASSOCIATED ALT RESTR. ACFT WAS NOT ABLE TO DSND TO MEET RESTR AND WAS VECTORED AWAY FROM ARR CORRIDOR AND INSTRUCTED TO MAINTAIN ALT FOR OPPOSITE DIRECTION TFC TO PASS BY. AIRCREW COMPLIED WITH REVISED INSTRUCTIONS AND WAS SUBSEQUENTLY RECLRED FOR ARR INTO LAS WITH NO FURTHER COMPLICATIONS. THIS SEEMS LIKE A HUMAN PERFORMANCE AND COM FAILURE BTWN THE PLTS FLYING WITH ASSUMPTION BY FO THAT BOTH ARR ROUTING AND ALT RESTRS WERE ENTERED INTO FMC WHEN THIS WAS NOT THE CASE. TURB ISSUES DISTRACTED AIRCREW FROM BACKING EACH OTHER UP.

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.