ZID controller lost separation with aircraft at FL310.

Attributes
ACN	600925
Time
Date	200311
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zid.artcc
State Reference	IN
Altitude	msl bound lower : 31000 msl bound upper : 32700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change cruise : level descent : vacating altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zid.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : developmental
Experience	controller military : 8 controller non radar : 4 controller time certified in position2 : 2
ASRS Report	600925
Person 2
Affiliation	government : faa
Function	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	faa : investigated
Miss Distance	vertical : 1700
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Intra Facility Coordination Failure Operational Error

Narrative:

An air carrier X flight was at FL330 as FL350 was unavailable. Air carrier Y had been switched to the sector above. The aircraft had become a factor with a military aircraft. At that point the controller in contact with aircraft asked if air carrier Y should be descended to FL310 to which the controller answered 'yes.' then he realized he had traffic at FL310. He then asked that air carrier X not be descended but it was too late. Air carrier X had gone down to FL327 with an air carrier Y at FL310.

Original NASA ASRS Text

Title: ZID CTLR LOST SEPARATION WITH ACFT AT FL310.

Narrative: AN ACR X FLT WAS AT FL330 AS FL350 WAS UNAVAILABLE. ACR Y HAD BEEN SWITCHED TO THE SECTOR ABOVE. THE ACFT HAD BECOME A FACTOR WITH A MIL ACFT. AT THAT POINT THE CTLR IN CONTACT WITH ACFT ASKED IF ACR Y SHOULD BE DSNDED TO FL310 TO WHICH THE CTLR ANSWERED 'YES.' THEN HE REALIZED HE HAD TFC AT FL310. HE THEN ASKED THAT ACR X NOT BE DSNDED BUT IT WAS TOO LATE. ACR X HAD GONE DOWN TO FL327 WITH AN ACR Y AT FL310.

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.