Enroute developmental controller described a loss of separation event during an attempt to descend a...

Attributes
ACN	980005
Time
Date	201111
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Aircraft 2
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Developmental
Person 2
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Altitude Excursion From Assigned Altitude

Narrative:

I was working the radar position as a developmental. I descended air carrier X to FL350 to get under an aircraft at FL360 still in the neighboring facility's airspace; 50 plus miles away and to meet the neighboring facility's LOA. At that time there was traffic 20 miles opposite direction at FL360 that I failed to see. I answered a few other calls and when I saw the situation the aircraft were 10.2 miles apart with air carrier X at FL365 and air carrier Y level at FL360. I expedited air carrier X to descend; but air carrier Y responded to TCAS and said he was descending. After traffic was called air carrier X advised they were climbing back up to FL370. Recommendation; when planning ahead always continue to scan for traffic in closer proximity.

Original NASA ASRS Text

Title: Enroute Developmental Controller described a loss of separation event during an attempt to descend an Air Carrier below another aircraft.

Narrative: I was working the RADAR position as a developmental. I descended Air Carrier X to FL350 to get under an aircraft at FL360 still in the neighboring facility's airspace; 50 plus miles away and to meet the neighboring facility's LOA. At that time there was traffic 20 miles opposite direction at FL360 that I failed to see. I answered a few other calls and when I saw the situation the aircraft were 10.2 miles apart with Air Carrier X at FL365 and Air Carrier Y level at FL360. I expedited Air Carrier X to descend; but Air Carrier Y responded to TCAS and said he was descending. After traffic was called Air Carrier X advised they were climbing back up to FL370. Recommendation; when planning ahead always continue to scan for traffic in closer proximity.

Data retrieved from NASA's ASRS site as of April 2012 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.

Enroute developmental controller described a loss of separation event during an attempt to descend an air carrier below another aircraft.