Narrative:

Aircraft #1 heading eastbound. Instructed by ATC to turn '15 degrees left' for traffic. 5-10 seconds later, TCASII intruder was noted on TCASII at 10 O'clock and 14 mi, 300 ft below and climbing. Seconds later, ATC issued '30 degree right turn for traffic' to aircraft #1 and also gave heading to aircraft #2. Seconds later, TCASII RA issued 'climb, climb.' aircraft #1 began climb. Simultaneously, ATC reissued '30 degree hard right turn' to aircraft #1, and reissued turn instructions to aircraft #2. Aircraft #1 deviated +1000 ft from original altitude and approximately 30 degrees from original heading. TCASII issued 'clear of conflict.' aircraft #1 returned to FL290 and resumed original course. We believe the original ATC directive for '15 degrees left' was probably supposed to be '15 degrees right.' however, both captain and first officer understood and read back '15 degrees left' at the original clearance.

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Original NASA ASRS Text

Title: DC9 FLC ASSIGNED INCORRECT TFC AVOIDANCE VECTOR.

Narrative: ACFT #1 HDG EBOUND. INSTRUCTED BY ATC TO TURN '15 DEGS L' FOR TFC. 5-10 SECONDS LATER, TCASII INTRUDER WAS NOTED ON TCASII AT 10 O'CLOCK AND 14 MI, 300 FT BELOW AND CLBING. SECONDS LATER, ATC ISSUED '30 DEG R TURN FOR TFC' TO ACFT #1 AND ALSO GAVE HDG TO ACFT #2. SECONDS LATER, TCASII RA ISSUED 'CLB, CLB.' ACFT #1 BEGAN CLB. SIMULTANEOUSLY, ATC REISSUED '30 DEG HARD R TURN' TO ACFT #1, AND REISSUED TURN INSTRUCTIONS TO ACFT #2. ACFT #1 DEVIATED +1000 FT FROM ORIGINAL ALT AND APPROX 30 DEGS FROM ORIGINAL HDG. TCASII ISSUED 'CLR OF CONFLICT.' ACFT #1 RETURNED TO FL290 AND RESUMED ORIGINAL COURSE. WE BELIEVE THE ORIGINAL ATC DIRECTIVE FOR '15 DEGS L' WAS PROBABLY SUPPOSED TO BE '15 DEGS R.' HOWEVER, BOTH CAPT AND FO UNDERSTOOD AND READ BACK '15 DEGS L' AT THE ORIGINAL CLRNC.

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.