Wrong aircraft acknowledged for descent clearance resulting in less than standard separation.

Attributes
ACN	118003
Time
Date	198907
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : yng
State Reference	OH
Altitude	msl bound lower : 12000 msl bound upper : 12000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	cruise other
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
ASRS Report	118003
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation other anomaly other
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	other
Consequence	Other
Miss Distance	horizontal : 18000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Two aircraft small aircraft X and small aircraft Y were descending on converging courses. Small aircraft Y took the altitude assignment of small aircraft X which resulted in loss of separation. Appears I missed readback.

Original NASA ASRS Text

Title: WRONG ACFT ACKNOWLEDGED FOR DESCENT CLRNC RESULTING IN LESS THAN STANDARD SEPARATION.

Narrative: TWO ACFT SMA X AND SMA Y WERE DESCENDING ON CONVERGING COURSES. SMA Y TOOK THE ALT ASSIGNMENT OF SMA X WHICH RESULTED IN LOSS OF SEPARATION. APPEARS I MISSED READBACK.

Data retrieved from NASA's ASRS site as of August 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.