Air carrier X same altitude assigned overtook aircraft Y and had less than standard separation. Syst...

Attributes
ACN	287128
Time
Date	199410
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : brv
State Reference	VA
Altitude	msl bound lower : 8000 msl bound upper : 8000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Route In Use	enroute : direct enroute airway : ric
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 1
ASRS Report	287128
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
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	faa : investigated
Miss Distance	horizontal : 2500 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

While working my third consecutive position in almost 2 hours (1 plus 50 total top) I observed 2 aircraft converging at 8000 ft at the northern border of my airspace. I immediately turned the trail air carrier X eastbound and called traffic at 12 O'clock and 1 mi. After the pilot acknowledged I turned the lead aircraft Y wbound and called traffic 6 O'clock and 1 mi. The trail aircraft X reported traffic in sight and I instructed him to maintain visual separation. I then descended the lead aircraft Y. After prescribed separation was achieved I turned both back on course. I believe a contributing factor which hindered early detection of the convergence to be the parameters of the conflict avoidance program. The ca alarm did not sound in sufficient time for action to be taken prior to loss of separation. In addition, the alarm often sounds at inappropriate moments (ie, when 2 aircraft have already passed), thereby lessening the importance of the alarm in the mind of the controller. It simply becomes 'backgnd noise.'

Original NASA ASRS Text

Title: ACR X SAME ALT ASSIGNED OVERTOOK ACFT Y AND HAD LTSS. SYS ERROR.

Narrative: WHILE WORKING MY THIRD CONSECUTIVE POS IN ALMOST 2 HRS (1 PLUS 50 TOTAL TOP) I OBSERVED 2 ACFT CONVERGING AT 8000 FT AT THE NORTHERN BORDER OF MY AIRSPACE. I IMMEDIATELY TURNED THE TRAIL ACR X EBOUND AND CALLED TFC AT 12 O'CLOCK AND 1 MI. AFTER THE PLT ACKNOWLEDGED I TURNED THE LEAD ACFT Y WBOUND AND CALLED TFC 6 O'CLOCK AND 1 MI. THE TRAIL ACFT X RPTED TFC IN SIGHT AND I INSTRUCTED HIM TO MAINTAIN VISUAL SEPARATION. I THEN DSNDED THE LEAD ACFT Y. AFTER PRESCRIBED SEPARATION WAS ACHIEVED I TURNED BOTH BACK ON COURSE. I BELIEVE A CONTRIBUTING FACTOR WHICH HINDERED EARLY DETECTION OF THE CONVERGENCE TO BE THE PARAMETERS OF THE CONFLICT AVOIDANCE PROGRAM. THE CA ALARM DID NOT SOUND IN SUFFICIENT TIME FOR ACTION TO BE TAKEN PRIOR TO LOSS OF SEPARATION. IN ADDITION, THE ALARM OFTEN SOUNDS AT INAPPROPRIATE MOMENTS (IE, WHEN 2 ACFT HAVE ALREADY PASSED), THEREBY LESSENING THE IMPORTANCE OF THE ALARM IN THE MIND OF THE CTLR. IT SIMPLY BECOMES 'BACKGND NOISE.'

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.

Air carrier X same altitude assigned overtook aircraft Y and had less than standard separation. System error.