ZID center controllers reported a loss of separation when communications were not completed. Both ai...

Attributes
ACN	1396908
Time
Date	201610
Local Time Of Day	1801-2400
Place
Locale Reference	ZID.ARTCC
State Reference	IN
Environment
Light	Night
Aircraft 1
Make Model Name	Medium Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Aircraft 2
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Person 2
Function	Handoff / Assist Enroute
Qualification	Air Traffic Control Developmental
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Published Material / Policy Deviation - Procedural Clearance

Narrative:

Aircraft Y was inbound to dtw; and I was working on getting 20 miles in trail. Aircraft X was southbound and already talking to sector 81. I had turned aircraft Y to the northwest to get the spacing; and continued on working throughout the sector. The heading had put aircraft Y in conflict with aircraft X; and the datablocks began flashing. I immediately turned aircraft Y to the east. The controller from sector 81 called in my green and asked if I wanted him to descend the aircraft X. At first I said he could descend; but then I had said to just leave the aircraft X and I would descend my aircraft Y. After I gave aircraft Y clearance down to FL300; I saw the aircraft X descending as well. The controller called me back to ask if I descended aircraft Y too because he descended the aircraft X. I didn't realize he had dialed out while I was still talking. My d-side then got a call saying that aircraft X was responding to an RA.better communication. I had not known that perhaps the other controller was no longer dialed into my line while I was still talking.

Original NASA ASRS Text

Title: ZID Center Controllers reported a loss of separation when communications were not completed. Both aircraft were descended by Controllers who thought the other aircraft was staying level.

Narrative: Aircraft Y was inbound to DTW; and I was working on getting 20 miles in trail. Aircraft X was southbound and already talking to Sector 81. I had turned Aircraft Y to the northwest to get the spacing; and continued on working throughout the sector. The heading had put Aircraft Y in conflict with Aircraft X; and the datablocks began flashing. I immediately turned Aircraft Y to the east. The controller from Sector 81 called in my green and asked if I wanted him to descend the Aircraft X. At first I said he could descend; but then I had said to just leave the Aircraft X and I would descend my Aircraft Y. After I gave Aircraft Y clearance down to FL300; I saw the Aircraft X descending as well. The Controller called me back to ask if I descended Aircraft Y too because he descended the Aircraft X. I didn't realize he had dialed out while I was still talking. My D-Side then got a call saying that Aircraft X was responding to an RA.Better communication. I had not known that perhaps the other controller was no longer dialed into my line while I was still talking.

Data retrieved from NASA's ASRS site 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.

ZID center controllers reported a loss of separation when communications were not completed. Both aircraft were descended by controllers who thought the other aircraft was staying level.