An air carrier B-727 had a TCASII alert in the traffic pattern.

Attributes
ACN	266758
Time
Date	199403
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : dfw
State Reference	TX
Altitude	agl bound lower : 2500 agl bound upper : 2500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : dfw
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	other : unknown
Flight Phase	descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : atp pilot : instrument pilot : flight engineer pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 3500 flight time type : 1100
ASRS Report	266758
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : airborne less severe non adherence : clearance other anomaly other other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : became reoriented flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

TCASII alerted on another aircraft turning final on the parallel runway. This alert caused all 3 pilots to search for the conflict while the captain was turning final. Because of the distraction, the captain overshot the runway, but corrected back to course without incident. Please note that we were concerned that the conflict was with VFR uncontrolled traffic rather than with the jet turning final simultaneously with us to the parallel. This confusion was caused, in part, by the fact that both aircraft were banking, which tends to make target acquisition more challenging. Also, both aircraft had merging/diverging vectors -- alarming but not dangerous.

Original NASA ASRS Text

Title: AN ACR B-727 HAD A TCASII ALERT IN THE TFC PATTERN.

Narrative: TCASII ALERTED ON ANOTHER ACFT TURNING FINAL ON THE PARALLEL RWY. THIS ALERT CAUSED ALL 3 PLTS TO SEARCH FOR THE CONFLICT WHILE THE CAPT WAS TURNING FINAL. BECAUSE OF THE DISTR, THE CAPT OVERSHOT THE RWY, BUT CORRECTED BACK TO COURSE WITHOUT INCIDENT. PLEASE NOTE THAT WE WERE CONCERNED THAT THE CONFLICT WAS WITH VFR UNCTLED TFC RATHER THAN WITH THE JET TURNING FINAL SIMULTANEOUSLY WITH US TO THE PARALLEL. THIS CONFUSION WAS CAUSED, IN PART, BY THE FACT THAT BOTH ACFT WERE BANKING, WHICH TENDS TO MAKE TARGET ACQUISITION MORE CHALLENGING. ALSO, BOTH ACFT HAD MERGING/DIVERGING VECTORS -- ALARMING BUT NOT DANGEROUS.

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.