DC9 flight crew assigned incorrect traffic avoidance vector.

Attributes
ACN	442530
Time
Date	199907
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : zid.artcc
State Reference	IN
Altitude	msl bound lower : 29000 msl bound upper : 30000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid.artcc
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zid.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 7800 flight time type : 200
ASRS Report	442530
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 4000 flight time type : 500
ASRS Report	442528
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne critical other anomaly other
Independent Detector	atc equipment : conflict alert aircraft equipment : tcas other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : returned to assigned altitude flight crew : took evasive action
Miss Distance	horizontal : 18000
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Deviation

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.

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.