Narrative:

I was the PF B737-300 at FL270 on the KEPEC1 RNAV arrival into las. ZLA cleared us to cross the misen RNAV fix at FL240. The pilot monitoring set FL240 into the altitude window and I set FL240 opposite the misen fix in the FMC. I selected descent on the FMC to determine top of descent. The FMC data indicated a top of descent of approximately 30 NM ahead. The pilot monitoring then selected the menu page to obtain the current ATIS for las. Several mins passed in obtaining this information, however the pilot monitoring stated that the information was 1 hour old and would change in several mins. The FMC cruise page was selected and then the pilot monitoring left center frequency to obtain station gate information. After a min or so the pilot monitoring returned to center frequency and selected menu again on the FMC to obtain the new/current ATIS. Several mins passed in obtaining this new data. ATC controller gave us a different ATC frequency and asked us what altitude we were at. I selected the descent page again and noted 2600 ft high, 12 mi past top of descent, which put us just several mi from our crossing restr at misen. A descent was initiated immediately to FL240 and the pilot monitoring checked in with the new ATC controller at FL240. No traffic conflicts were noted on the TCASII. On RNAV arrs in the B-300 series aircraft situational awareness is compromised due to several factors. Both pilot monitoring and PF are in navigation mode and so all situation data is provided via the FMC. In this case there was only one FMC display/head, so while the FMC is being utilized for other tasks situational awareness can, and in this case was, compromised. In this aircraft on RNAV arrs I feel that obtaining ATIS via the #2 communication would be a worthwhile operation policy or the installation of dual FMC's. We both knew that a descent was required very soon, however with the opc, station call, ATIS, and landing briefing, and other distrs, it is easy to lose situational awareness. We missed the bigger picture because we were trying to comply with all of the details.

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Original NASA ASRS Text

Title: B737-300 CREW MISSED A XING RESTR ON THE KEPEC 1 RNAV ARR TO LAS. ACFT IS ONLY EQUIPPED WITH A SINGLE FMS, AND HAS NO NAV DISPLAY.

Narrative: I WAS THE PF B737-300 AT FL270 ON THE KEPEC1 RNAV ARR INTO LAS. ZLA CLRED US TO CROSS THE MISEN RNAV FIX AT FL240. THE PLT MONITORING SET FL240 INTO THE ALT WINDOW AND I SET FL240 OPPOSITE THE MISEN FIX IN THE FMC. I SELECTED DSCNT ON THE FMC TO DETERMINE TOP OF DSCNT. THE FMC DATA INDICATED A TOP OF DSCNT OF APPROX 30 NM AHEAD. THE PLT MONITORING THEN SELECTED THE MENU PAGE TO OBTAIN THE CURRENT ATIS FOR LAS. SEVERAL MINS PASSED IN OBTAINING THIS INFO, HOWEVER THE PLT MONITORING STATED THAT THE INFO WAS 1 HR OLD AND WOULD CHANGE IN SEVERAL MINS. THE FMC CRUISE PAGE WAS SELECTED AND THEN THE PLT MONITORING LEFT CTR FREQ TO OBTAIN STATION GATE INFO. AFTER A MIN OR SO THE PLT MONITORING RETURNED TO CTR FREQ AND SELECTED MENU AGAIN ON THE FMC TO OBTAIN THE NEW/CURRENT ATIS. SEVERAL MINS PASSED IN OBTAINING THIS NEW DATA. ATC CTLR GAVE US A DIFFERENT ATC FREQ AND ASKED US WHAT ALT WE WERE AT. I SELECTED THE DSCNT PAGE AGAIN AND NOTED 2600 FT HIGH, 12 MI PAST TOP OF DSCNT, WHICH PUT US JUST SEVERAL MI FROM OUR XING RESTR AT MISEN. A DSCNT WAS INITIATED IMMEDIATELY TO FL240 AND THE PLT MONITORING CHKED IN WITH THE NEW ATC CTLR AT FL240. NO TFC CONFLICTS WERE NOTED ON THE TCASII. ON RNAV ARRS IN THE B-300 SERIES ACFT SITUATIONAL AWARENESS IS COMPROMISED DUE TO SEVERAL FACTORS. BOTH PLT MONITORING AND PF ARE IN NAV MODE AND SO ALL SIT DATA IS PROVIDED VIA THE FMC. IN THIS CASE THERE WAS ONLY ONE FMC DISPLAY/HEAD, SO WHILE THE FMC IS BEING UTILIZED FOR OTHER TASKS SITUATIONAL AWARENESS CAN, AND IN THIS CASE WAS, COMPROMISED. IN THIS ACFT ON RNAV ARRS I FEEL THAT OBTAINING ATIS VIA THE #2 COM WOULD BE A WORTHWHILE OP POLICY OR THE INSTALLATION OF DUAL FMC'S. WE BOTH KNEW THAT A DSCNT WAS REQUIRED VERY SOON, HOWEVER WITH THE OPC, STATION CALL, ATIS, AND LNDG BRIEFING, AND OTHER DISTRS, IT IS EASY TO LOSE SITUATIONAL AWARENESS. WE MISSED THE BIGGER PICTURE BECAUSE WE WERE TRYING TO COMPLY WITH ALL OF THE DETAILS.

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.