ZOB controller described a loss of separation event when failing to note conflicting traffic prior t...

Narrative:

I was working an increasingly busier session on radar at the sector 68. The E170 was northwest and level at FL340; requesting FL320 for moderate chop. I descended the E170; switched communications to sector 67; and lost the data block for an A320 in a mess of data blocks; who was eastbound level at FL330. When I realized separation was going to be lost; I attempted to turn the A320 away from the E170; but the instructions were not received until the third transmission; for some apparent reason. As the A320 was making the turn I instructed; sector 67 was turning the E170 away from the A320 at the same time; and separation was regained; but the A320 responded to a RA which instructed them to climb; and separation was lost on the next radar hit. Work on my scan; but why would TCAS climb an aircraft into one at a higher altitude?

Original NASA ASRS Text

Title: ZOB Controller described a loss of separation event when failing to note conflicting traffic prior to issuing a descent. The reporter stated the TCAS RA resolution provided compounded the conflict.

Narrative: I was working an increasingly busier session on RADAR at the Sector 68. The E170 was northwest and level at FL340; requesting FL320 for moderate chop. I descended the E170; switched communications to Sector 67; and lost the Data Block for an A320 in a mess of Data Blocks; who was eastbound level at FL330. When I realized separation was going to be lost; I attempted to turn the A320 away from the E170; but the instructions were not received until the third transmission; for some apparent reason. As the A320 was making the turn I instructed; Sector 67 was turning the E170 away from the A320 at the same time; and separation was regained; but the A320 responded to a RA which instructed them to climb; and separation was lost on the next RADAR hit. Work on my scan; but why would TCAS climb an aircraft into one at a higher altitude?

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1045304
Time
Date	201210
Local Time Of Day	1801-2400
Place
Locale Reference	ZOB.ARTCC
State Reference	OH
Aircraft 1
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Aircraft 2
Make Model Name	EMB ERJ 170/175 ER/LR
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict

ZOB controller described a loss of separation event when failing to note conflicting traffic prior to issuing a descent. The reporter stated the TCAS RA resolution provided compounded the conflict.