Narrative:

Airspace was saturated with IFR arrs 27, at time of occurrence or just preceding occurrence. Final radar controller to runway 23 had as many as 11 aircraft in airspace and final extended out to 26 mi. I was working arrival east and observed air carrier X and Y approaching on converging course, 10 mi northwest of airport. Before I could react I heard the arrival west controller declare that one of the aircraft had the other in sight. This was after separation had been lost. Air carrier X took TCASII evasive maneuvers from Y and climbed into aircraft Z above him at 8000 ft. Vertical separation with this aircraft Z was also lost. Apparently the arrival controller had issued a heading to an aircraft Y which was read back by a preceding handoff to final. The preceding handoff, air carrier X, read back the instructions because they seemed unusual. The controller somewhat busy at the time confirmed the instructions and air carrier X turned back into following traffic Y and separation was lost.

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Original NASA ASRS Text

Title: ACR X TCASII RA NON ADHERENCE TO ATC CLRNC HAD LTSS FROM ACR Y AND Z. SYS ERROR.

Narrative: AIRSPACE WAS SATURATED WITH IFR ARRS 27, AT TIME OF OCCURRENCE OR JUST PRECEDING OCCURRENCE. FINAL RADAR CTLR TO RWY 23 HAD AS MANY AS 11 ACFT IN AIRSPACE AND FINAL EXTENDED OUT TO 26 MI. I WAS WORKING ARR E AND OBSERVED ACR X AND Y APCHING ON CONVERGING COURSE, 10 MI NW OF ARPT. BEFORE I COULD REACT I HEARD THE ARR W CTLR DECLARE THAT ONE OF THE ACFT HAD THE OTHER IN SIGHT. THIS WAS AFTER SEPARATION HAD BEEN LOST. ACR X TOOK TCASII EVASIVE MANEUVERS FROM Y AND CLBED INTO ACFT Z ABOVE HIM AT 8000 FT. VERT SEPARATION WITH THIS ACFT Z WAS ALSO LOST. APPARENTLY THE ARR CTLR HAD ISSUED A HDG TO AN ACFT Y WHICH WAS READ BACK BY A PRECEDING HDOF TO FINAL. THE PRECEDING HDOF, ACR X, READ BACK THE INSTRUCTIONS BECAUSE THEY SEEMED UNUSUAL. THE CTLR SOMEWHAT BUSY AT THE TIME CONFIRMED THE INSTRUCTIONS AND ACR X TURNED BACK INTO FOLLOWING TFC Y AND SEPARATION WAS LOST.

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.