Narrative:

This event occurred at denver center, south area, sector 28 radar position. With training in progress, air carrier X was descended to FL260 through an en route aircraft, air carrier Y, at FL310. At the time the descent clearance was given to air carrier X, he was not a factor with air carrier Y because their rtes were parallel. But with additional traffic crossing with air carrier Y at FL310, air carrier Y was given a 25 degree left turn for traffic putting him in confliction with air carrier X in his descent to FL260 with air carrier X being south of air carrier Y. After the confliction was realized air carrier X was turned south and air carrier Y was turned north to increase separation between the 2 aircraft. I believe the training on the sector at the time of the incident was a factor in the cause of the error and also lack of awareness on the part of the trainee and the instructor.

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Original NASA ASRS Text

Title: CTLR FORGETS ABOUT TFC AND TURNS ACFT INTO ANOTHER ACFT ON A PARALLEL COURSE RESULTING IN LTSS.

Narrative: THIS EVENT OCCURRED AT DENVER CTR, S AREA, SECTOR 28 RADAR POS. WITH TRAINING IN PROGRESS, ACR X WAS DSNDED TO FL260 THROUGH AN ENRTE ACFT, ACR Y, AT FL310. AT THE TIME THE DSCNT CLRNC WAS GIVEN TO ACR X, HE WAS NOT A FACTOR WITH ACR Y BECAUSE THEIR RTES WERE PARALLEL. BUT WITH ADDITIONAL TFC XING WITH ACR Y AT FL310, ACR Y WAS GIVEN A 25 DEG L TURN FOR TFC PUTTING HIM IN CONFLICTION WITH ACR X IN HIS DSCNT TO FL260 WITH ACR X BEING S OF ACR Y. AFTER THE CONFLICTION WAS REALIZED ACR X WAS TURNED S AND ACR Y WAS TURNED N TO INCREASE SEPARATION BTWN THE 2 ACFT. I BELIEVE THE TRAINING ON THE SECTOR AT THE TIME OF THE INCIDENT WAS A FACTOR IN THE CAUSE OF THE ERROR AND ALSO LACK OF AWARENESS ON THE PART OF THE TRAINEE AND THE INSTRUCTOR.

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.