Less than standard separation between two air carrier aircraft. Operational error.

Attributes
ACN	90507
Time
Date	198807
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : tys
State Reference	TN
Altitude	msl bound lower : 29000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid artcc : ztl tower : msy
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other descent other
Route In Use	enroute airway : j43
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 8000 flight time type : 120
ASRS Report	90507
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance none taken : unable other
Consequence	Other
Miss Distance	horizontal : 18000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Inter Facility Coordination Failure

Narrative:

We were flight DH zero (aircraft X). Our clearance was given to company flight DH one (aircraft Z). This put us in a possible traffic conflict with air carrier Y (conflicting traffic air carrier Y was never observed) which was resolved with an emergency descent from FL310 to FL290 and a 90 degree turn at 30 degree bank from 355 degree to 270 degree. There was quite a bit of confusion in atlanta center, reflected in people yelling in the background at atl center. Callback conversation with reporter revealed following information. Thinks conflicting traffic was air carrier Y (airline name/type). Pretty sure ZTL controller was trainee and emergency turn and descent was issued by another voice on frequency. I explained that at 80 mi north of tys they should have been changed over to ZID soon after passing tys. He thinks controller was trying to give them vectors, but was using company flight Z call sign. Right after they made turn and descent to FL290 they were changed to ZID frequency. That is first time they heard air carrier Y on same frequency. Had feeling something bad was happening from anxiety in controller voice so were looking for traffic, but never did see air carrier Y. Right wing may have blocked vision to right during steep evasive turn. Has had no followup on incident from ATC.

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN TWO ACR ACFT. OPERATIONAL ERROR.

Narrative: WE WERE FLT DH ZERO (ACFT X). OUR CLRNC WAS GIVEN TO COMPANY FLT DH ONE (ACFT Z). THIS PUT US IN A POSSIBLE TFC CONFLICT WITH ACR Y (CONFLICTING TFC ACR Y WAS NEVER OBSERVED) WHICH WAS RESOLVED WITH AN EMER DSCNT FROM FL310 TO FL290 AND A 90 DEG TURN AT 30 DEG BANK FROM 355 DEG TO 270 DEG. THERE WAS QUITE A BIT OF CONFUSION IN ATLANTA CENTER, REFLECTED IN PEOPLE YELLING IN THE BACKGROUND AT ATL CENTER. CALLBACK CONVERSATION WITH RPTR REVEALED FOLLOWING INFO. THINKS CONFLICTING TFC WAS ACR Y (AIRLINE NAME/TYPE). PRETTY SURE ZTL CTLR WAS TRAINEE AND EMER TURN AND DSCNT WAS ISSUED BY ANOTHER VOICE ON FREQ. I EXPLAINED THAT AT 80 MI NORTH OF TYS THEY SHOULD HAVE BEEN CHANGED OVER TO ZID SOON AFTER PASSING TYS. HE THINKS CTLR WAS TRYING TO GIVE THEM VECTORS, BUT WAS USING COMPANY FLT Z CALL SIGN. RIGHT AFTER THEY MADE TURN AND DSCNT TO FL290 THEY WERE CHANGED TO ZID FREQ. THAT IS FIRST TIME THEY HEARD ACR Y ON SAME FREQ. HAD FEELING SOMETHING BAD WAS HAPPENING FROM ANXIETY IN CTLR VOICE SO WERE LOOKING FOR TFC, BUT NEVER DID SEE ACR Y. RIGHT WING MAY HAVE BLOCKED VISION TO RIGHT DURING STEEP EVASIVE TURN. HAS HAD NO FOLLOWUP ON INCIDENT FROM ATC.

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.