Air carrier was issued a climb and conflicted with opposite direction traffic.

Attributes
ACN	119436
Time
Date	198908
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : elp
State Reference	TX
Altitude	msl bound lower : 29000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zab tower : hou
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude
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
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	119436
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	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	horizontal : 24000 vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X eastbound at FL290 requested FL330. FL330 was not available due to traffic already at FL330. Approximately 10 mins later FL330 became available and air carrier X was issued a climb to FL330. With air carrier Y at FL310 wbound, head-on, ca was activated, and within seconds air carrier X was issued an immediate descent to FL290, but sep was lost. Perhaps a contributing factor was air carrier Y's data block in a 2/3 position to avoid overlapping data blocks. This is an abnormal position and when I did a traffic search prior to issuing climb to air carrier X, I missed seeing air carrier Y.

Original NASA ASRS Text

Title: ACR WAS ISSUED A CLIMB AND CONFLICTED WITH OPPOSITE DIRECTION TRAFFIC.

Narrative: ACR X EBND AT FL290 REQUESTED FL330. FL330 WAS NOT AVAILABLE DUE TO TFC ALREADY AT FL330. APPROX 10 MINS LATER FL330 BECAME AVAILABLE AND ACR X WAS ISSUED A CLB TO FL330. WITH ACR Y AT FL310 WBOUND, HEAD-ON, CA WAS ACTIVATED, AND WITHIN SECS ACR X WAS ISSUED AN IMMEDIATE DSCNT TO FL290, BUT SEP WAS LOST. PERHAPS A CONTRIBUTING FACTOR WAS ACR Y'S DATA BLOCK IN A 2/3 POS TO AVOID OVERLAPPING DATA BLOCKS. THIS IS AN ABNORMAL POS AND WHEN I DID A TFC SEARCH PRIOR TO ISSUING CLB TO ACR X, I MISSED SEEING ACR Y.

Data retrieved from NASA's ASRS site as of August 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.