Small aircraft Y had less than standard separation from air carrier X. System error.

Attributes
ACN	187116
Time
Date	199108
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dcf
State Reference	FL
Altitude	msl bound lower : 10000 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : okc
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Retractable Gear
Flight Phase	cruise other
Route In Use	enroute : direct enroute airway : zjx
Flight Plan	IFR
Aircraft 2
Operator	general aviation : corporate
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller radar : 12
ASRS Report	187116
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 non adherence : clearance
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 27900 vertical : 400
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Intra Facility Coordination Failure Operational Error

Narrative:

Small aircraft X southwest of ocala, fl, northbound at 10000 MSL. Small transport Y sebound was handed off to me from a high altitude sector. The data block indicated the aircraft was descending to 11000 MSL. When small transport Y reported on frequency he reported at 16000 with pilot's discretion to 10000 (I did not hear 10000 until review of the tapes). When the aircraft were about 8 mi apart conflict alert went off. I asked small transport Y his altitude and he said 10000. I told small transport Y to descend to 9000 and expedite and turn left heading zero niner zero. Small aircraft X had already been switched to the next center sector, so I told that controller to turn small aircraft X west. Separation decreased to 4.65 mi and 400 ft vertical. This error was due to an inconsistent data in the data block and verbal communication.

Original NASA ASRS Text

Title: SMA Y HAD LTSS FROM ACR X. SYS ERROR.

Narrative: SMA X SW OF OCALA, FL, NBOUND AT 10000 MSL. SMT Y SEBOUND WAS HANDED OFF TO ME FROM A HIGH ALT SECTOR. THE DATA BLOCK INDICATED THE ACFT WAS DSNDING TO 11000 MSL. WHEN SMT Y RPTED ON FREQ HE RPTED AT 16000 WITH PLT'S DISCRETION TO 10000 (I DID NOT HEAR 10000 UNTIL REVIEW OF THE TAPES). WHEN THE ACFT WERE ABOUT 8 MI APART CONFLICT ALERT WENT OFF. I ASKED SMT Y HIS ALT AND HE SAID 10000. I TOLD SMT Y TO DSND TO 9000 AND EXPEDITE AND TURN L HDG ZERO NINER ZERO. SMA X HAD ALREADY BEEN SWITCHED TO THE NEXT CENTER SECTOR, SO I TOLD THAT CTLR TO TURN SMA X W. SEPARATION DECREASED TO 4.65 MI AND 400 FT VERT. THIS ERROR WAS DUE TO AN INCONSISTENT DATA IN THE DATA BLOCK AND VERBAL COM.

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.