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

Attributes
ACN	308458
Time
Date	199506
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : atl
State Reference	GA
Altitude	msl bound lower : 7000 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : atl
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent : approach descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 10000 flight time type : 4000
ASRS Report	308458
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : undershoot conflict : airborne less severe non adherence : clearance non adherence : published procedure non adherence : required legal separation other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action other
Consequence	Other
Miss Distance	horizontal : 500 vertical : 800
Supplementary
Air Traffic Incident	Pilot Deviation

Narrative:

Air carrier X being vectored from macey arrival to runway 26R ILS. 170 degree heading, 180 KTS, descending to 6000 ft. I saw air carrier Y come out of clouds about 1 O'clock position. I told captain about traffic. As Y closed on us the captain started a left turn and climb. TCASII RA followed. Controller issued a turn to 090 degree heading and climb to 7000 ft. Normal approach and landing completed.

Original NASA ASRS Text

Title: ACR X TCASII RA HAD LTSS FROM ACR Y. SYS ERROR.

Narrative: ACR X BEING VECTORED FROM MACEY ARR TO RWY 26R ILS. 170 DEG HDG, 180 KTS, DSNDING TO 6000 FT. I SAW ACR Y COME OUT OF CLOUDS ABOUT 1 O'CLOCK POS. I TOLD CAPT ABOUT TFC. AS Y CLOSED ON US THE CAPT STARTED A L TURN AND CLB. TCASII RA FOLLOWED. CTLR ISSUED A TURN TO 090 DEG HDG AND CLB TO 7000 FT. NORMAL APCH AND LNDG COMPLETED.

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.