ZID ARTCC controller descended a G5 through altitude occupied by another G5 resulting in a loss of s...

Attributes
ACN	547905
Time
Date	200205
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : ape.vortac
State Reference	OH
Altitude	msl bound lower : 45000 msl bound upper : 4600
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zid.artcc
Operator	general aviation : corporate
Make Model Name	Gulfstream V
Operating Under FAR Part	Part 91
Flight Phase	descent : vacating altitude
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zid.artcc
Operator	other
Make Model Name	Gulfstream V
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
ASRS Report	547905
Person 2
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment : conflict alert atc equipment other atc equipment : radar other controllera
Resolutory Action	none taken : detected after the fact none taken : insufficient time
Miss Distance	horizontal : 16200 vertical : 1000
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Aircraft X inbound to ind at FL470 needed to start down and was descended to FL370. Aircraft Y was sebound at FL450. Data block overlap blocked altitude readout and I thought the aircraft was at FL350. Conflict alert activated. Turns were issued but too late for standard separation.

Original NASA ASRS Text

Title: ZID ARTCC CTLR DSNDED A G5 THROUGH ALT OCCUPIED BY ANOTHER G5 RESULTING IN A LOSS OF SEPARATION.

Narrative: ACFT X INBOUND TO IND AT FL470 NEEDED TO START DOWN AND WAS DSNDED TO FL370. ACFT Y WAS SEBOUND AT FL450. DATA BLOCK OVERLAP BLOCKED ALT READOUT AND I THOUGHT THE ACFT WAS AT FL350. CONFLICT ALERT ACTIVATED. TURNS WERE ISSUED BUT TOO LATE FOR STANDARD SEPARATION.

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.

ZID ARTCC controller descended a G5 through altitude occupied by another G5 resulting in a loss of separation.