Narrative:

During the night approach into mountainous terrain; often complicated by thunderstorm deviation; operators are experiencing database anomalies. The clearance is via the rio negro one STAR which allows a transition to the prevailing runway 36. Twice I have experienced a left turn depiction from the teardrop rather than the depicted right turn required by the procedure. The left (incorrect) turn depicted takes you towards higher terrain and results in considerable heads down by the operators trying to build a reasonable radial/DME solution to mimic the approach plate. Whatever the fix; it should be part of the air carrier pages as an advisory.callback conversation with reporter revealed the following information: the reporter stated that this FMS programming error has been discussed at his air carrier by himself and many other pilots who have seen the same machine behavior on the B737 FMS. The primary issue is that when the arrival is coupled with the ILS the FMC will every time build a left hand turn after rio negro and attempt to intercept the ILS from the east. This requires a descending turn into higher terrain or being heads down attempting to reprogram the FMC routing for the right turn to rio negro and then on to the ILS. A method of avoiding this is to leave a discontinuity between the arrival and the approach. In this event the correct procedure is depicted and flown with a rt turn after rio negro. The pilots can then close the discontinuity and couple the ILS. The reporter is concerned because at his air carrier many new capts are coming on line as are first officer's returning from furlough who are new to the aircraft and int'l flying. Additionally this is not listed as a special airport by this air carrier requiring a crew to review it prior to flying there. The reporter stated that there is always WX; always a need to deviate for WX; and pilots tend to want to descend out of the WX on this arrival. Reporter feels that is a dangerous combination and could lead to a CFIT.

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Original NASA ASRS Text

Title: A B737 PILOT REPORTS AN FMC DATABASE ERROR DEPICTS A LEFT TURN INTO HIGH TERRAIN VERSUS A RIGHT TURN AS DEPICTED ON THE SKRG RIO NEGRO ARRIVAL.

Narrative: DURING THE NIGHT APCH INTO MOUNTAINOUS TERRAIN; OFTEN COMPLICATED BY TSTM DEV; OPERATORS ARE EXPERIENCING DATABASE ANOMALIES. THE CLRNC IS VIA THE RIO NEGRO ONE STAR WHICH ALLOWS A TRANSITION TO THE PREVAILING RWY 36. TWICE I HAVE EXPERIENCED A LEFT TURN DEPICTION FROM THE TEARDROP RATHER THAN THE DEPICTED RIGHT TURN REQUIRED BY THE PROC. THE LEFT (INCORRECT) TURN DEPICTED TAKES YOU TOWARDS HIGHER TERRAIN AND RESULTS IN CONSIDERABLE HEADS DOWN BY THE OPERATORS TRYING TO BUILD A REASONABLE RADIAL/DME SOLUTION TO MIMIC THE APCH PLATE. WHATEVER THE FIX; IT SHOULD BE PART OF THE ACR PAGES AS AN ADVISORY.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE REPORTER STATED THAT THIS FMS PROGRAMMING ERROR HAS BEEN DISCUSSED AT HIS ACR BY HIMSELF AND MANY OTHER PILOTS WHO HAVE SEEN THE SAME MACHINE BEHAVIOR ON THE B737 FMS. THE PRIMARY ISSUE IS THAT WHEN THE ARRIVAL IS COUPLED WITH THE ILS THE FMC WILL EVERY TIME BUILD A LEFT HAND TURN AFTER RIO NEGRO AND ATTEMPT TO INTERCEPT THE ILS FROM THE EAST. THIS REQUIRES A DESCENDING TURN INTO HIGHER TERRAIN OR BEING HEADS DOWN ATTEMPTING TO REPROGRAM THE FMC ROUTING FOR THE RIGHT TURN TO RIO NEGRO AND THEN ON TO THE ILS. A METHOD OF AVOIDING THIS IS TO LEAVE A DISCONTINUITY BETWEEN THE ARRIVAL AND THE APPROACH. IN THIS EVENT THE CORRECT PROCEDURE IS DEPICTED AND FLOWN WITH A RT TURN AFTER RIO NEGRO. THE PILOTS CAN THEN CLOSE THE DISCONTINUITY AND COUPLE THE ILS. THE REPORTER IS CONCERNED BECAUSE AT HIS ACR MANY NEW CAPTS ARE COMING ON LINE AS ARE FO'S RETURNING FROM FURLOUGH WHO ARE NEW TO THE ACFT AND INT'L FLYING. ADDITIONALLY THIS IS NOT LISTED AS A SPECIAL AIRPORT BY THIS ACR REQUIRING A CREW TO REVIEW IT PRIOR TO FLYING THERE. THE REPORTER STATED THAT THERE IS ALWAYS WX; ALWAYS A NEED TO DEVIATE FOR WX; AND PILOTS TEND TO WANT TO DESCEND OUT OF THE WX ON THIS ARRIVAL. RPTR FEELS THAT IS A DANGEROUS COMBINATION AND COULD LEAD TO A CFIT.

Data retrieved from NASA's ASRS site as of January 2009 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.