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

Attributes
ACN	176356
Time
Date	199104
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : lga
State Reference	NY
Altitude	msl bound lower : 1500 msl bound upper : 1500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90 tracon : lax
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Route In Use	departure other departure sid : sid
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Route In Use	departure other departure sid : sid
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 10000 flight time type : 500
ASRS Report	176356
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	none taken : anomaly accepted
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 6000 vertical : 100
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X's TCAS was in TA mode and warned, 'traffic, traffic,' in climb out from lga. First observed yellow circle with +300 at 11 O'clock. Symbol passed 1-4 mi left of air carrier X and changed through +200, +100 and -100' as it passed behind my left wing. I questioned ATC and they advised that the traffic was company air carrier Y that departed ahead of me, but that they did not have a good paint on him.

Original NASA ASRS Text

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

Narrative: ACR X'S TCAS WAS IN TA MODE AND WARNED, 'TFC, TFC,' IN CLBOUT FROM LGA. FIRST OBSERVED YELLOW CIRCLE WITH +300 AT 11 O'CLOCK. SYMBOL PASSED 1-4 MI LEFT OF ACR X AND CHANGED THROUGH +200, +100 AND -100' AS IT PASSED BEHIND MY LEFT WING. I QUESTIONED ATC AND THEY ADVISED THAT THE TFC WAS COMPANY ACR Y THAT DEPARTED AHEAD OF ME, BUT THAT THEY DID NOT HAVE A GOOD PAINT ON HIM.

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.