Flight crew of visual to ord drifted off centerline of runway. Approach controller gave vectors.

Attributes
ACN	128855
Time
Date	198911
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : ord
State Reference	IL
Altitude	msl bound lower : 3500 msl bound upper : 3500
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : ord artcc : zob
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Flight Phase	descent : approach descent other
Route In Use	approach : visual enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : flight engineer pilot : instrument pilot : atp
Experience	flight time last 90 days : 160 flight time total : 11000 flight time type : 130
ASRS Report	128855
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On arrival in ord area from pappi, turn south, vector to final (visual parallel for 27R). After final vector to visual final controller requested us to return to centerline on final approach course as we were drifting south and could conflict with traffic for 27L. This traffic was to our rear and above us. At this time I took control of airplane and turned 30 degree further to right, setting up an intercept to final from the south side of course. I then turned control back over to first officer and we continued without further comment from ATC for normal approach and landing.

Original NASA ASRS Text

Title: FLT CREW OF VISUAL TO ORD DRIFTED OFF CENTERLINE OF RWY. APCH CTLR GAVE VECTORS.

Narrative: ON ARR IN ORD AREA FROM PAPPI, TURN SOUTH, VECTOR TO FINAL (VISUAL PARALLEL FOR 27R). AFTER FINAL VECTOR TO VISUAL FINAL CTLR REQUESTED US TO RETURN TO CENTERLINE ON FINAL APCH COURSE AS WE WERE DRIFTING SOUTH AND COULD CONFLICT WITH TFC FOR 27L. THIS TFC WAS TO OUR REAR AND ABOVE US. AT THIS TIME I TOOK CONTROL OF AIRPLANE AND TURNED 30 DEG FURTHER TO RIGHT, SETTING UP AN INTERCEPT TO FINAL FROM THE SOUTH SIDE OF COURSE. I THEN TURNED CONTROL BACK OVER TO F/O AND WE CONTINUED WITHOUT FURTHER COMMENT FROM ATC FOR NORMAL APCH AND LNDG.

Data retrieved from NASA's ASRS site as of August 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.