Less than standard separation between commuter and air carrier. Operational error.

Attributes
ACN	102158
Time
Date	198901
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : atl
State Reference	GA
Altitude	msl bound lower : 11000 msl bound upper : 11500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : atl
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
ASRS Report	102158
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	other other : unspecified atc
Resolutory Action	none taken : detected after the fact
Consequence	faa : investigated
Miss Distance	horizontal : 12000 vertical : 500
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Commuter X departed runway 27R and was climbed to 14000'. I wrote 10000' on the strip and I missed the readback while calling to the flight data to send a departure message on the aircraft. Aircraft X was observed leaving 11500' and questioned about his altitude. He said that he was at 11500', I then issued traffic Y at 11000' and 2 miles which he saw and said he would maintain visual on the traffic. Had I not called to flight data I think I would have caught the discrepancy in the readback.

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN COMMUTER AND ACR. OPERATIONAL ERROR.

Narrative: COMMUTER X DEPARTED RWY 27R AND WAS CLIMBED TO 14000'. I WROTE 10000' ON THE STRIP AND I MISSED THE READBACK WHILE CALLING TO THE FLT DATA TO SEND A DEP MESSAGE ON THE ACFT. ACFT X WAS OBSERVED LEAVING 11500' AND QUESTIONED ABOUT HIS ALT. HE SAID THAT HE WAS AT 11500', I THEN ISSUED TFC Y AT 11000' AND 2 MILES WHICH HE SAW AND SAID HE WOULD MAINTAIN VISUAL ON THE TFC. HAD I NOT CALLED TO FLT DATA I THINK I WOULD HAVE CAUGHT THE DISCREPANCY IN THE 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.