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B737-700 flight crew, during las idale RNAV departure, has heading deviation due to an FMC anomaly.
| Attributes | |
| ACN | 557179 |
| Time | |
| Date | 200208 |
| Day | Mon |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : las.airport |
| State Reference | NV |
| Altitude | msl single value : 7000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : l30.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other other vortac |
| Flight Phase | climbout : intermediate altitude |
| Route In Use | departure sid : idale enroute : direct enroute other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 7 flight time total : 27500 flight time type : 19000 |
| ASRS Report | 557179 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | non adherence : published procedure non adherence : clearance other spatial deviation |
| Independent Detector | atc equipment other atc equipment : radar other controllerb other flight crewa |
| Resolutory Action | controller : issued new clearance controller : issued advisory flight crew : returned to original clearance flight crew : overrode automation |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Cleared las to lax RNAV idale 1 departure. The first officer and I verified all RNAV departure procedures on checklist complied with including verifying all fixes, altitudes on the route page of the CDU. During taxi out, we were changed from runway 19L to runway 25R. We entered the new data in the CDU and everything looked ok. After takeoff, RNAV was engaged at 400 ft, autoplt at 1000 ft (captain flying). Aircraft flew departure normally. We leveled off at 7000 ft due to arrival traffic downwind at 8000 ft. The leveloff was between andyy and idale. Crossing idale, we were given climb to 9000 ft and I noticed that the aircraft had rolled out about 210 degrees. I increased the EFIS scale from 5-20 and noticed that boach was not in our system on the map or the CDU. I immediately engaged the heading select and set 150 degrees. Then I told the first officer to manually enter boach. The system tried to go from idale direct to hector. I don't know why. ATC called us about the deviation after we had started the turn to 150 degrees. I informed them that our navigation computer had fouled up and we were trying to re-enter boach. They gave us a vector to join the bld 210 degree radial. ZLA gave us a number to call in las during cruise. I explained all the above to the supervisor and he told me they were submitting an internal las ATC report. He said they had over 100 reports generated in the last 2 weeks. Boach is a fix on the RNAV departure no matter what runway is utilized. I don't know why it was not in or dropped out of our active navigation base.
Original NASA ASRS Text
Title: B737-700 FLC, DURING LAS IDALE RNAV DEP, HAS HDG DEV DUE TO AN FMC ANOMALY.
Narrative: CLRED LAS TO LAX RNAV IDALE 1 DEP. THE FO AND I VERIFIED ALL RNAV DEP PROCS ON CHKLIST COMPLIED WITH INCLUDING VERIFYING ALL FIXES, ALTS ON THE RTE PAGE OF THE CDU. DURING TAXI OUT, WE WERE CHANGED FROM RWY 19L TO RWY 25R. WE ENTERED THE NEW DATA IN THE CDU AND EVERYTHING LOOKED OK. AFTER TKOF, RNAV WAS ENGAGED AT 400 FT, AUTOPLT AT 1000 FT (CAPT FLYING). ACFT FLEW DEP NORMALLY. WE LEVELED OFF AT 7000 FT DUE TO ARR TFC DOWNWIND AT 8000 FT. THE LEVELOFF WAS BTWN ANDYY AND IDALE. XING IDALE, WE WERE GIVEN CLB TO 9000 FT AND I NOTICED THAT THE ACFT HAD ROLLED OUT ABOUT 210 DEGS. I INCREASED THE EFIS SCALE FROM 5-20 AND NOTICED THAT BOACH WAS NOT IN OUR SYS ON THE MAP OR THE CDU. I IMMEDIATELY ENGAGED THE HDG SELECT AND SET 150 DEGS. THEN I TOLD THE FO TO MANUALLY ENTER BOACH. THE SYS TRIED TO GO FROM IDALE DIRECT TO HECTOR. I DON'T KNOW WHY. ATC CALLED US ABOUT THE DEV AFTER WE HAD STARTED THE TURN TO 150 DEGS. I INFORMED THEM THAT OUR NAV COMPUTER HAD FOULED UP AND WE WERE TRYING TO RE-ENTER BOACH. THEY GAVE US A VECTOR TO JOIN THE BLD 210 DEG RADIAL. ZLA GAVE US A NUMBER TO CALL IN LAS DURING CRUISE. I EXPLAINED ALL THE ABOVE TO THE SUPVR AND HE TOLD ME THEY WERE SUBMITTING AN INTERNAL LAS ATC RPT. HE SAID THEY HAD OVER 100 RPTS GENERATED IN THE LAST 2 WKS. BOACH IS A FIX ON THE RNAV DEP NO MATTER WHAT RWY IS UTILIZED. I DON'T KNOW WHY IT WAS NOT IN OR DROPPED OUT OF OUR ACTIVE NAV BASE.
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.