ZOB controller described a loss of separation event when sector combination coordination was unclear...

Attributes
ACN	865759
Time
Date	200912
Local Time Of Day	1801-2400
Place
Locale Reference	ZNY.ARTCC
State Reference	NY
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	DC-9 50
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Radar 21 Flight Crew Total 200
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict
Miss Distance	Horizontal 18000 Vertical 300

Narrative:

End of shift; supervisor was combing sector into midnight configuration. I assumed 2 of the 4 high sectors; with base altitude of FL330. He\she then came over and told me that 'I have it all;' which I interpreted to mean I had assumed the intermediate highs as well; (FL240-FL320). However this was not the case. I further believe I had assumed that airspace when looking at the controller who as working that sector was turned away from scope talking to a trainee. I was working a DC9 at FL330 that needed to descend to FL290 per letter of agreement. I initiated the clearance thinking; I owned the airspace. Conflict alert was immediate with traffic at FL320. I then realized intermediate sector was still open. I heard that controller turn aircraft left. I turned 65 degrees right. Loss of separation occurred; closest proximity was 3 mile 300 ft.

Original NASA ASRS Text

Title: ZOB controller described a loss of separation event when sector combination coordination was unclear and an aircraft was issued a descent into airspace that in fact had not yet been released/combined.

Narrative: End of shift; Supervisor was combing sector into midnight configuration. I assumed 2 of the 4 high sectors; with base altitude of FL330. He\she then came over and told me that 'I have it all;' which I interpreted to mean I had assumed the intermediate highs as well; (FL240-FL320). However this was not the case. I further believe I had assumed that airspace when looking at the Controller who as working that sector was turned away from scope talking to a Trainee. I was working a DC9 at FL330 that needed to descend to FL290 per letter of agreement. I initiated the clearance thinking; I owned the airspace. Conflict alert was immediate with traffic at FL320. I then realized intermediate sector was still open. I heard that Controller turn aircraft left. I turned 65 degrees right. Loss of separation occurred; closest proximity was 3 mile 300 FT.

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.