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

Attributes
ACN	132572
Time
Date	199001
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : oal
State Reference	CA
Altitude	msl bound lower : 33000 msl bound upper : 34300
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zoa
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
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
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 8
ASRS Report	132572
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	none taken : insufficient time
Consequence	faa : investigated
Miss Distance	horizontal : 24600 vertical : 1300
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was working ZOA sector 33 by myself. Traffic built to approximately 13 aircraft on frequency. Air carrier X and air carrier Y were being in-trailed to sfo via modesto. About 3 mins prior to the error, I was advised that another controller was coming to help. He got to the sector within a minute of the error. There was data block congestion adding to the complexity, and several aircraft converging over the oal VORTAC at FL350 and FL310. I feel that if an additional controller had been at the sector prior to the traffic building to its most complex, this error could have been prevented. Callback conversation with reporter revealed the following: the reporter stated he thought he had sep between air carrier X and Y when he descended air carrier Y to air carrier X's altitude. C/a activated, but he did not have time to react. Miss distance was 1300' and 4.1 mi. Reporter has taken a demotion and transferred to a tower. This was mutually agreed to by the reporter and FAA management.

Original NASA ASRS Text

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

Narrative: I WAS WORKING ZOA SECTOR 33 BY MYSELF. TFC BUILT TO APPROX 13 ACFT ON FREQ. ACR X AND ACR Y WERE BEING IN-TRAILED TO SFO VIA MODESTO. ABOUT 3 MINS PRIOR TO THE ERROR, I WAS ADVISED THAT ANOTHER CTLR WAS COMING TO HELP. HE GOT TO THE SECTOR WITHIN A MINUTE OF THE ERROR. THERE WAS DATA BLOCK CONGESTION ADDING TO THE COMPLEXITY, AND SEVERAL ACFT CONVERGING OVER THE OAL VORTAC AT FL350 AND FL310. I FEEL THAT IF AN ADDITIONAL CTLR HAD BEEN AT THE SECTOR PRIOR TO THE TFC BUILDING TO ITS MOST COMPLEX, THIS ERROR COULD HAVE BEEN PREVENTED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: THE RPTR STATED HE THOUGHT HE HAD SEP BTWN ACR X AND Y WHEN HE DSNDED ACR Y TO ACR X'S ALT. C/A ACTIVATED, BUT HE DID NOT HAVE TIME TO REACT. MISS DISTANCE WAS 1300' AND 4.1 MI. RPTR HAS TAKEN A DEMOTION AND TRANSFERRED TO A TWR. THIS WAS MUTUALLY AGREED TO BY THE RPTR AND FAA MGMNT.

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.