Narrative:

Prior to departure in sjc, the company route was programmed into the box and verified. Air safety inspector was onboard for an en route check of cockpit crew. Subsequent modifications to the route included direct to czq later, direct to lidat and later, direct to bty. Also, the runway assigned by ATIS information, runway 25L was programmed into the arrival routing. En route, we were carefully backing up the LNAV route with appropriate VOR and radials. Extra care was taken because of the FAA inspection. Everything was triple checked instead of just doublechked, as any pilot getting a check ride would do. On the las vegas approach frequency, after crossing tragr at or above 14000 ft and 250 KTS, we were given a descent to 11000 ft and a speed reduction to 210 KTS. Assuring those instructions were received and understood and being implemented, the airplane turned to the next fix. Somehow that fix was shand (10 DME from las on the runway 25L localizer) not ipumy as it should have been. I am not sure how much time passed, but it could not have been long. Approach control asked if we were on the tragr arrival. I answered 'affirmative.' the reply was, are you headed for shand, and I replied yes, it is 30.0 DME in front of us. I knew immediately that was not the fix we should have been heading toward. Approach gave us direct bld and a phone number to call. I am not sure what caused this, but in part of my investigation I learned the aircraft previous to me had done the same thing. I suspect there was some kind of glitch with the programmed arrival. We should have noticed the error prior to the turn, and I am not sure how far off the assigned course we were, but I can say approach control caught it very quickly. I feel certain if they had not caught it so quickly, we would have taken corrective action very soon. As far as how to prevent this, I can only say, as we have been told by company, to use extreme caution that the programmed route is the correct route. Las approachs have been the subject on numerous read before flies. I live in las and consequently fly in and out of here often. I am familiar with the problems here, and as a result, use extreme caution. With an FAA inspector watching our every move, I was not being lax during this arrival. I still had a problem. Callback conversation with reporter revealed the following information: the route of flight is entered as a canned (preprogrammed) routing. It ends at the tragr intersection. This was a recurrent problem and was reported to the company, who issued a notice of the problem encountered. It took several days to get the word out, so this became a recurring problem. Supplemental information from acn 572434: I remember inputting the correct arrival and runway into the CDU, removing the discontinuity and verifying the correct route/altitudes before accepting. I did not reverify the legs page after the first input. This same type of event happened on an earlier pairing, but we caught the aircraft making the wrong turn and corrected the heading. I believe the contributing factors are that I was preoccupied with the airspeed and altitude change, and did not reverify the legs page. This entire event happened in less than 2 mins. When you input the arrival and runway into the CDU and clear the discontinuities, the FMC removes the legs after tragr. While on the jumpseat commuting back to las, I asked the crew flying if they would put the tragr 2 arrival into the CDU. The result was the same, and the discontinuities removed the legs after tragr. The first officer that was flying my commuter flight home said that he had heard this happens to other pilots. I believe there is an error in the FMC for the tragr 2 arrival, and it should be re-evaluated to see if there is a flaw.

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Original NASA ASRS Text

Title: A COURSE DEV ON THE TRAGR RNAV 2 ARR TO LAS, NV.

Narrative: PRIOR TO DEP IN SJC, THE COMPANY RTE WAS PROGRAMMED INTO THE BOX AND VERIFIED. AIR SAFETY INSPECTOR WAS ONBOARD FOR AN ENRTE CHK OF COCKPIT CREW. SUBSEQUENT MODIFICATIONS TO THE RTE INCLUDED DIRECT TO CZQ LATER, DIRECT TO LIDAT AND LATER, DIRECT TO BTY. ALSO, THE RWY ASSIGNED BY ATIS INFO, RWY 25L WAS PROGRAMMED INTO THE ARR ROUTING. ENRTE, WE WERE CAREFULLY BACKING UP THE LNAV RTE WITH APPROPRIATE VOR AND RADIALS. EXTRA CARE WAS TAKEN BECAUSE OF THE FAA INSPECTION. EVERYTHING WAS TRIPLE CHKED INSTEAD OF JUST DOUBLECHKED, AS ANY PLT GETTING A CHK RIDE WOULD DO. ON THE LAS VEGAS APCH FREQ, AFTER XING TRAGR AT OR ABOVE 14000 FT AND 250 KTS, WE WERE GIVEN A DSCNT TO 11000 FT AND A SPD REDUCTION TO 210 KTS. ASSURING THOSE INSTRUCTIONS WERE RECEIVED AND UNDERSTOOD AND BEING IMPLEMENTED, THE AIRPLANE TURNED TO THE NEXT FIX. SOMEHOW THAT FIX WAS SHAND (10 DME FROM LAS ON THE RWY 25L LOC) NOT IPUMY AS IT SHOULD HAVE BEEN. I AM NOT SURE HOW MUCH TIME PASSED, BUT IT COULD NOT HAVE BEEN LONG. APCH CTL ASKED IF WE WERE ON THE TRAGR ARR. I ANSWERED 'AFFIRMATIVE.' THE REPLY WAS, ARE YOU HEADED FOR SHAND, AND I REPLIED YES, IT IS 30.0 DME IN FRONT OF US. I KNEW IMMEDIATELY THAT WAS NOT THE FIX WE SHOULD HAVE BEEN HEADING TOWARD. APCH GAVE US DIRECT BLD AND A PHONE NUMBER TO CALL. I AM NOT SURE WHAT CAUSED THIS, BUT IN PART OF MY INVESTIGATION I LEARNED THE ACFT PREVIOUS TO ME HAD DONE THE SAME THING. I SUSPECT THERE WAS SOME KIND OF GLITCH WITH THE PROGRAMMED ARR. WE SHOULD HAVE NOTICED THE ERROR PRIOR TO THE TURN, AND I AM NOT SURE HOW FAR OFF THE ASSIGNED COURSE WE WERE, BUT I CAN SAY APCH CTL CAUGHT IT VERY QUICKLY. I FEEL CERTAIN IF THEY HAD NOT CAUGHT IT SO QUICKLY, WE WOULD HAVE TAKEN CORRECTIVE ACTION VERY SOON. AS FAR AS HOW TO PREVENT THIS, I CAN ONLY SAY, AS WE HAVE BEEN TOLD BY COMPANY, TO USE EXTREME CAUTION THAT THE PROGRAMMED RTE IS THE CORRECT RTE. LAS APCHS HAVE BEEN THE SUBJECT ON NUMEROUS READ BEFORE FLIES. I LIVE IN LAS AND CONSEQUENTLY FLY IN AND OUT OF HERE OFTEN. I AM FAMILIAR WITH THE PROBS HERE, AND AS A RESULT, USE EXTREME CAUTION. WITH AN FAA INSPECTOR WATCHING OUR EVERY MOVE, I WAS NOT BEING LAX DURING THIS ARR. I STILL HAD A PROB. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RTE OF FLT IS ENTERED AS A CANNED (PREPROGRAMMED) ROUTING. IT ENDS AT THE TRAGR INTXN. THIS WAS A RECURRENT PROB AND WAS RPTED TO THE COMPANY, WHO ISSUED A NOTICE OF THE PROB ENCOUNTERED. IT TOOK SEVERAL DAYS TO GET THE WORD OUT, SO THIS BECAME A RECURRING PROB. SUPPLEMENTAL INFO FROM ACN 572434: I REMEMBER INPUTTING THE CORRECT ARR AND RWY INTO THE CDU, REMOVING THE DISCONTINUITY AND VERIFYING THE CORRECT RTE/ALTS BEFORE ACCEPTING. I DID NOT REVERIFY THE LEGS PAGE AFTER THE FIRST INPUT. THIS SAME TYPE OF EVENT HAPPENED ON AN EARLIER PAIRING, BUT WE CAUGHT THE ACFT MAKING THE WRONG TURN AND CORRECTED THE HDG. I BELIEVE THE CONTRIBUTING FACTORS ARE THAT I WAS PREOCCUPIED WITH THE AIRSPD AND ALT CHANGE, AND DID NOT REVERIFY THE LEGS PAGE. THIS ENTIRE EVENT HAPPENED IN LESS THAN 2 MINS. WHEN YOU INPUT THE ARR AND RWY INTO THE CDU AND CLR THE DISCONTINUITIES, THE FMC REMOVES THE LEGS AFTER TRAGR. WHILE ON THE JUMPSEAT COMMUTING BACK TO LAS, I ASKED THE CREW FLYING IF THEY WOULD PUT THE TRAGR 2 ARR INTO THE CDU. THE RESULT WAS THE SAME, AND THE DISCONTINUITIES REMOVED THE LEGS AFTER TRAGR. THE FO THAT WAS FLYING MY COMMUTER FLT HOME SAID THAT HE HAD HEARD THIS HAPPENS TO OTHER PLTS. I BELIEVE THERE IS AN ERROR IN THE FMC FOR THE TRAGR 2 ARR, AND IT SHOULD BE RE-EVALUATED TO SEE IF THERE IS A FLAW.

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.