Narrative:

En route to phx airport, descending on the FOSSL1 arrival, it was not noticed that 'sacho' fix was not in the legs page of the FMC. As a result our aircraft tracked north of desired course. When this was pointed out to us by ZAB the controller cleared us direct to sacho. Then, later requested we intercept zuni 242. While setting up navaids for intercept controller asked us if we were intercepting zuni 242 radial. We said we were. He then gave us a 270 degree heading. Later he cleared us direct FOSSL1. By telephone, later, to ZAB we discovered that we were close to another aircraft. This being the case, I feel the controller should have given us a shallower angle for the intercept of the zuni 242 and should have pointed out the traffic. He also should have stated the importance of not going (keep the turn tight) south of zuni 242. A 62 degree heading change in a short distance is too much and causes excessive 'G' loading for crew and passenger. Supplemental information from acn 193377: flying pilot directed me to program sacho into the FMC. He began a gentle left turn in the direction of sacho. Controller then directed us to 'fly 180 degree heading to intercept zuni (zun VORTAC) 242 degree radial.' PF flew the assigned heading. He also used FMC to determine sacho position which is along zun 242 radial. FMC showed hard right turn for the intercept. This was confirmed by using my HSI switch to VOR/ILS mode with zun 242 dialed in course selector window. PF began hard right turn to intercept. Center controller simultaneously asked if we were intercepting, and I said we were. He then directed us to fly a 270 degree heading. PF flew the assigned 270 degree heading and intercepted the assigned radial. At this point, I left the primary frequency and obtained phx ATIS. When I returned to VHF primary, center executed a handoff. A short time after we established contact with new sector, controller advised of a 'possible pilot deviation in the previous sector, and to contact center by telephone (number was given) for further information.' flight continued to phx. On arrival, captain confirmed that ZAB had noted our deviation south of the zun 242 radial and that it was sufficient to approach other traffic, opposite direction, 4 mi away and 1000 ft below us. My initial concern centered on the fact that the FMC did not properly contain the sacho intersection on the FOSSL1 STAR for phx. However, this is not the basis for FAA's investigation. If our aircraft had been allowed to continue on the selected RNAV route, the conflict would have been avoided and the zun 242 radial would have been joined only a few mi west of sacho intersection with minor deviation right of course (away from conflicting traffic). At no time during the process did center controller advise of oncoming traffic and to take more aggressive action to intercept radial or delay descent to avoid conflict. Contributing factors: bank angles limited all altitude due to aircraft gross weight, and rapid course intercept due to strong tailwinds encountered on assigned southerly heading during descent. Controller also tracked our position outbound of gallup VORTAC for over 8 mins and no doubt noted that we were not in fact proceeding on the STAR. His assigned headings came late, and combined with the assigned descent profile produced this conflict.

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Original NASA ASRS Text

Title: HDG TRACK POS DEV CREATES A POTENTIAL CONFLICT LTSS AS ACR MLG FAILS TO COMPLY WITH APCH PROC STAR.

Narrative: ENRTE TO PHX ARPT, DSNDING ON THE FOSSL1 ARR, IT WAS NOT NOTICED THAT 'SACHO' FIX WAS NOT IN THE LEGS PAGE OF THE FMC. AS A RESULT OUR ACFT TRACKED N OF DESIRED COURSE. WHEN THIS WAS POINTED OUT TO US BY ZAB THE CTLR CLRED US DIRECT TO SACHO. THEN, LATER REQUESTED WE INTERCEPT ZUNI 242. WHILE SETTING UP NAVAIDS FOR INTERCEPT CTLR ASKED US IF WE WERE INTERCEPTING ZUNI 242 RADIAL. WE SAID WE WERE. HE THEN GAVE US A 270 DEG HDG. LATER HE CLRED US DIRECT FOSSL1. BY TELEPHONE, LATER, TO ZAB WE DISCOVERED THAT WE WERE CLOSE TO ANOTHER ACFT. THIS BEING THE CASE, I FEEL THE CTLR SHOULD HAVE GIVEN US A SHALLOWER ANGLE FOR THE INTERCEPT OF THE ZUNI 242 AND SHOULD HAVE POINTED OUT THE TFC. HE ALSO SHOULD HAVE STATED THE IMPORTANCE OF NOT GOING (KEEP THE TURN TIGHT) S OF ZUNI 242. A 62 DEG HDG CHANGE IN A SHORT DISTANCE IS TOO MUCH AND CAUSES EXCESSIVE 'G' LOADING FOR CREW AND PAX. SUPPLEMENTAL INFO FROM ACN 193377: FLYING PLT DIRECTED ME TO PROGRAM SACHO INTO THE FMC. HE BEGAN A GENTLE L TURN IN THE DIRECTION OF SACHO. CTLR THEN DIRECTED US TO 'FLY 180 DEG HDG TO INTERCEPT ZUNI (ZUN VORTAC) 242 DEG RADIAL.' PF FLEW THE ASSIGNED HDG. HE ALSO USED FMC TO DETERMINE SACHO POS WHICH IS ALONG ZUN 242 RADIAL. FMC SHOWED HARD R TURN FOR THE INTERCEPT. THIS WAS CONFIRMED BY USING MY HSI SWITCH TO VOR/ILS MODE WITH ZUN 242 DIALED IN COURSE SELECTOR WINDOW. PF BEGAN HARD R TURN TO INTERCEPT. CTR CTLR SIMULTANEOUSLY ASKED IF WE WERE INTERCEPTING, AND I SAID WE WERE. HE THEN DIRECTED US TO FLY A 270 DEG HDG. PF FLEW THE ASSIGNED 270 DEG HDG AND INTERCEPTED THE ASSIGNED RADIAL. AT THIS POINT, I LEFT THE PRIMARY FREQ AND OBTAINED PHX ATIS. WHEN I RETURNED TO VHF PRIMARY, CTR EXECUTED A HDOF. A SHORT TIME AFTER WE ESTABLISHED CONTACT WITH NEW SECTOR, CTLR ADVISED OF A 'POSSIBLE PLTDEV IN THE PREVIOUS SECTOR, AND TO CONTACT CTR BY TELEPHONE (NUMBER WAS GIVEN) FOR FURTHER INFO.' FLT CONTINUED TO PHX. ON ARR, CAPT CONFIRMED THAT ZAB HAD NOTED OUR DEV S OF THE ZUN 242 RADIAL AND THAT IT WAS SUFFICIENT TO APCH OTHER TFC, OPPOSITE DIRECTION, 4 MI AWAY AND 1000 FT BELOW US. MY INITIAL CONCERN CTRED ON THE FACT THAT THE FMC DID NOT PROPERLY CONTAIN THE SACHO INTXN ON THE FOSSL1 STAR FOR PHX. HOWEVER, THIS IS NOT THE BASIS FOR FAA'S INVESTIGATION. IF OUR ACFT HAD BEEN ALLOWED TO CONTINUE ON THE SELECTED RNAV RTE, THE CONFLICT WOULD HAVE BEEN AVOIDED AND THE ZUN 242 RADIAL WOULD HAVE BEEN JOINED ONLY A FEW MI W OF SACHO INTXN WITH MINOR DEV R OF COURSE (AWAY FROM CONFLICTING TFC). AT NO TIME DURING THE PROCESS DID CTR CTLR ADVISE OF ONCOMING TFC AND TO TAKE MORE AGGRESSIVE ACTION TO INTERCEPT RADIAL OR DELAY DSCNT TO AVOID CONFLICT. CONTRIBUTING FACTORS: BANK ANGLES LIMITED ALL ALT DUE TO ACFT GROSS WT, AND RAPID COURSE INTERCEPT DUE TO STRONG TAILWINDS ENCOUNTERED ON ASSIGNED SOUTHERLY HDG DURING DSCNT. CTLR ALSO TRACKED OUR POS OUTBOUND OF GALLUP VORTAC FOR OVER 8 MINS AND NO DOUBT NOTED THAT WE WERE NOT IN FACT PROCEEDING ON THE STAR. HIS ASSIGNED HDGS CAME LATE, AND COMBINED WITH THE ASSIGNED DSCNT PROFILE PRODUCED THIS CONFLICT.

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.