Air carrier X had less than standard separation from air carrier Y. System error.

Attributes
ACN	154787
Time
Date	199008
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : atl
State Reference	GA
Altitude	msl bound lower : 7000 msl bound upper : 7500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : atl
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
ASRS Report	154787
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : developmental
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 12000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Intra Facility Coordination Failure Operational Error

Narrative:

I was working the ar-a and ar-V, final position, combined with light to moderate traffic with an ATC trnee at the time of the error. Air carrier X was on the north downwind for atl descending to 7000' for runway 26R. Air carrier Y was descending to 6000' on a base leg for runway 26R. Air carrier X was level at 7000' eastbound. Air carrier Y was converging on air carrier X southbound leaving 7500' for 6000'. At this point I, the instrument, took the position. Air carrier Y had not reported on the frequency even though it had been approximately 30 seconds since he had been given the frequency change. I instructed air carrier Y to turn right heading 270 degrees. There was no acknowledgement. Traffic was issued to air carrier X. 'No contact' was his reply. I then issued evasive instructions to air carrier X. This occurred approximately 13 mi northeast of atl. Later another turn was issued to air carrier Y, 'turn right heading 250 degrees to join the localizer.' air carrier Y responded to this instruction. This was the first time that I knew that I had 2-WAY communication with the aircraft. During this period another trnee was working the tar (feeder position). Contributing factors: 1) air carrier Y not switched sooner. 2) why did it take air carrier Y so long to change frequencys? 3) air carrier X could possibly been descended out of 7000' sooner. I personally believe that a trnee should not feed another trnee.

Original NASA ASRS Text

Title: ACR X HAD LESS THAN STANDARD SEPARATION FROM ACR Y. SYSTEM ERROR.

Narrative: I WAS WORKING THE AR-A AND AR-V, FINAL POS, COMBINED WITH LIGHT TO MODERATE TFC WITH AN ATC TRNEE AT THE TIME OF THE ERROR. ACR X WAS ON THE N DOWNWIND FOR ATL DSNDING TO 7000' FOR RWY 26R. ACR Y WAS DSNDING TO 6000' ON A BASE LEG FOR RWY 26R. ACR X WAS LEVEL AT 7000' EBND. ACR Y WAS CONVERGING ON ACR X SBND LEAVING 7500' FOR 6000'. AT THIS POINT I, THE INSTR, TOOK THE POS. ACR Y HAD NOT RPTED ON THE FREQ EVEN THOUGH IT HAD BEEN APPROX 30 SECS SINCE HE HAD BEEN GIVEN THE FREQ CHANGE. I INSTRUCTED ACR Y TO TURN RIGHT HDG 270 DEGS. THERE WAS NO ACKNOWLEDGEMENT. TFC WAS ISSUED TO ACR X. 'NO CONTACT' WAS HIS REPLY. I THEN ISSUED EVASIVE INSTRUCTIONS TO ACR X. THIS OCCURRED APPROX 13 MI NE OF ATL. LATER ANOTHER TURN WAS ISSUED TO ACR Y, 'TURN RIGHT HDG 250 DEGS TO JOIN THE LOC.' ACR Y RESPONDED TO THIS INSTRUCTION. THIS WAS THE FIRST TIME THAT I KNEW THAT I HAD 2-WAY COM WITH THE ACFT. DURING THIS PERIOD ANOTHER TRNEE WAS WORKING THE TAR (FEEDER POS). CONTRIBUTING FACTORS: 1) ACR Y NOT SWITCHED SOONER. 2) WHY DID IT TAKE ACR Y SO LONG TO CHANGE FREQS? 3) ACR X COULD POSSIBLY BEEN DSNDED OUT OF 7000' SOONER. I PERSONALLY BELIEVE THAT A TRNEE SHOULD NOT FEED ANOTHER TRNEE.

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.