Narrative:

After a long duty day, and holding at vcn, was vectored for ILS runway 27R in phl. When on an intercept heading and cleared for the approach, while descending through 3500 ft for 3000 ft, upon localizer capture the airplane started a right turn (instead of left). I took control of the aircraft, turned off the autoplt and flight director and manually continued down to 3000 ft and reversed the turn back to the left to intercept final approach course. Received and complied with RA to monitor vertical speed. Complied with radar vectors in box pattern to re-intercept the approach gave the aircraft to the first officer while I reprogrammed the FMGC. The approach and landing were without fault. After a long day, we were taken by surprise with the right turn and were much too busy to figure out what may have gone wrong. More concerned with where we were going next. After landing, checked the second flight plan which was copied from the primary flight plan prior to takeoff, it was correct. I do not know the cause for the incorrect turn at localizer capture, but when things go wrong, the cockpit gets very busy and the automation becomes more of a distraction from flying and looking for traffic than a help! Supplemental information from acn 635674: received and acknowledged a dogleg turn to final and approach clearance. Within 1 min, aircraft turned completely away from final approach course into the path of the aircraft Y following him in on the final. Because of his deviation, I was forced to turn air carrier Y out of his way, but into the flight path of yet the next arrival. Because I was forced to react to prevent this collision, my only option was to turn air carrier Y sbound. Additionally, air carrier X descended through his assigned altitude and required even further instructions from me. I had no idea what this aircraft was doing, would do and it required all of my attention, leaving none for the 6 other aircraft. Obviously, this crew needed to not only pay attention to instructions, but be familiar enough with the environment to know that a nebound heading would not be the direction to the airport.

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Original NASA ASRS Text

Title: A319 FLT CREW ON DOGLEG TO FINAL AT PHL TURNS AWAY FROM INTERCEPT, CAUSING EVENTUAL LOSS OF SEPARATION WITH THIRD ACFT ON FINAL BEHIND RPTR.

Narrative: AFTER A LONG DUTY DAY, AND HOLDING AT VCN, WAS VECTORED FOR ILS RWY 27R IN PHL. WHEN ON AN INTERCEPT HDG AND CLRED FOR THE APCH, WHILE DSNDING THROUGH 3500 FT FOR 3000 FT, UPON LOC CAPTURE THE AIRPLANE STARTED A R TURN (INSTEAD OF L). I TOOK CTL OF THE ACFT, TURNED OFF THE AUTOPLT AND FLT DIRECTOR AND MANUALLY CONTINUED DOWN TO 3000 FT AND REVERSED THE TURN BACK TO THE L TO INTERCEPT FINAL APCH COURSE. RECEIVED AND COMPLIED WITH RA TO MONITOR VERT SPD. COMPLIED WITH RADAR VECTORS IN BOX PATTERN TO RE-INTERCEPT THE APCH GAVE THE ACFT TO THE FO WHILE I REPROGRAMMED THE FMGC. THE APCH AND LNDG WERE WITHOUT FAULT. AFTER A LONG DAY, WE WERE TAKEN BY SURPRISE WITH THE R TURN AND WERE MUCH TOO BUSY TO FIGURE OUT WHAT MAY HAVE GONE WRONG. MORE CONCERNED WITH WHERE WE WERE GOING NEXT. AFTER LNDG, CHKED THE SECOND FLT PLAN WHICH WAS COPIED FROM THE PRIMARY FLT PLAN PRIOR TO TKOF, IT WAS CORRECT. I DO NOT KNOW THE CAUSE FOR THE INCORRECT TURN AT LOC CAPTURE, BUT WHEN THINGS GO WRONG, THE COCKPIT GETS VERY BUSY AND THE AUTOMATION BECOMES MORE OF A DISTR FROM FLYING AND LOOKING FOR TFC THAN A HELP! SUPPLEMENTAL INFO FROM ACN 635674: RECEIVED AND ACKNOWLEDGED A DOGLEG TURN TO FINAL AND APCH CLRNC. WITHIN 1 MIN, ACFT TURNED COMPLETELY AWAY FROM FINAL APCH COURSE INTO THE PATH OF THE ACFT Y FOLLOWING HIM IN ON THE FINAL. BECAUSE OF HIS DEV, I WAS FORCED TO TURN ACR Y OUT OF HIS WAY, BUT INTO THE FLT PATH OF YET THE NEXT ARR. BECAUSE I WAS FORCED TO REACT TO PREVENT THIS COLLISION, MY ONLY OPTION WAS TO TURN ACR Y SBOUND. ADDITIONALLY, ACR X DSNDED THROUGH HIS ASSIGNED ALT AND REQUIRED EVEN FURTHER INSTRUCTIONS FROM ME. I HAD NO IDEA WHAT THIS ACFT WAS DOING, WOULD DO AND IT REQUIRED ALL OF MY ATTN, LEAVING NONE FOR THE 6 OTHER ACFT. OBVIOUSLY, THIS CREW NEEDED TO NOT ONLY PAY ATTN TO INSTRUCTIONS, BUT BE FAMILIAR ENOUGH WITH THE ENVIRONMENT TO KNOW THAT A NEBOUND HDG WOULD NOT BE THE DIRECTION TO THE ARPT.

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.