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

Attributes
ACN	187347
Time
Date	199108
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : bce
State Reference	UT
Altitude	msl bound lower : 33000 msl bound upper : 33000
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : direct
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 Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : flight data
Qualification	controller : radar
Experience	controller military : 4 controller radar : 1
ASRS Report	187347
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	187432
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 18000 vertical : 1000
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X en route to dfw at FL330. Air carrier Y nebound originally at FL330 and the r-man descended to FL310 for traffic. At the time of the incident I was briefing my relief. Just prior to air carrier Y being climbed I told my relief that air carrier Y needed to go back to FL330 when clear of traffic. Just prior to unplugging I heard the r-man climb air carrier Y to FL330. I marked the strip and unplugged. Only 3 or 4 aircraft to the sector. Callback conversation with reporter revealed the following information: reporter experience 1 yr fpl and 4 yrs military. Air carrier X and Y proximity 3 mi and 1000 ft. Reporter stated when conflict alert activated the radar controller descended air carrier Y back to FL310. The radar controller had stated he forgot air carrier X was at FL330 data tags were overlapping so he climbed air carrier Y. System error was filed. Supplemental information from acn 187432: I just sat down to work sector D-46 at ZLC. During the briefing I was advised that air carrier Y was at FL310 for traffic and was to be climbed to FL330 clear of traffic. During the briefing, the clearance to FL330 was given. I started to sequence flight progress strips when I noticed the conflict alert go off. I asked the radar controller what was going on. He said that air carrier Y was climbing. I asked if he was assigned FL310 (the data block showed FL330). He said he was assigned FL330. I asked 'what about air carrier X.' it was at this time we realized what had happened.

Original NASA ASRS Text

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

Narrative: ACR X ENRTE TO DFW AT FL330. ACR Y NEBOUND ORIGINALLY AT FL330 AND THE R-MAN DSNDED TO FL310 FOR TFC. AT THE TIME OF THE INCIDENT I WAS BRIEFING MY RELIEF. JUST PRIOR TO ACR Y BEING CLBED I TOLD MY RELIEF THAT ACR Y NEEDED TO GO BACK TO FL330 WHEN CLR OF TFC. JUST PRIOR TO UNPLUGGING I HEARD THE R-MAN CLB ACR Y TO FL330. I MARKED THE STRIP AND UNPLUGGED. ONLY 3 OR 4 ACFT TO THE SECTOR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR EXPERIENCE 1 YR FPL AND 4 YRS MIL. ACR X AND Y PROX 3 MI AND 1000 FT. RPTR STATED WHEN CONFLICT ALERT ACTIVATED THE RADAR CTLR DSNDED ACR Y BACK TO FL310. THE RADAR CTLR HAD STATED HE FORGOT ACR X WAS AT FL330 DATA TAGS WERE OVERLAPPING SO HE CLBED ACR Y. SYS ERROR WAS FILED. SUPPLEMENTAL INFO FROM ACN 187432: I JUST SAT DOWN TO WORK SECTOR D-46 AT ZLC. DURING THE BRIEFING I WAS ADVISED THAT ACR Y WAS AT FL310 FOR TFC AND WAS TO BE CLBED TO FL330 CLR OF TFC. DURING THE BRIEFING, THE CLRNC TO FL330 WAS GIVEN. I STARTED TO SEQUENCE FLT PROGRESS STRIPS WHEN I NOTICED THE CONFLICT ALERT GO OFF. I ASKED THE RADAR CTLR WHAT WAS GOING ON. HE SAID THAT ACR Y WAS CLBING. I ASKED IF HE WAS ASSIGNED FL310 (THE DATA BLOCK SHOWED FL330). HE SAID HE WAS ASSIGNED FL330. I ASKED 'WHAT ABOUT ACR X.' IT WAS AT THIS TIME WE REALIZED WHAT HAD HAPPENED.

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.