Atx X same altitude assigned had less than standard separation from small aircraft Y. System error.

Attributes
ACN	306044
Time
Date	199505
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mxe
State Reference	PA
Altitude	msl bound lower : 4000 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : phl
Operator	common carrier : air taxi
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 135
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Cessna Aircraft Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
ASRS Report	306044
Person 2
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 12000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was working north departure at phl, with about 10 aircraft under control, 2 of which were untagged by computer. When I was given several aircraft crossing the departure paths at different altitudes I stopped the departures. After that I became so involved with most of the aircraft that I didn't see atx X and small aircraft Y approaching the mxe VOR simultaneously at 4000 ft until they were less than 3 mi apart. I transmitted 'X climb immediately and maintain 5000 ft. Traffic 9 O'clock 2 mi, northbound, 4000, a cessna.' he did and was at 5000 ft almost instantaneously. Another controller was already working Y and told me that Y was maintaining visual separation with X.

Original NASA ASRS Text

Title: ATX X SAME ALT ASSIGNED HAD LTSS FROM SMA Y. SYS ERROR.

Narrative: I WAS WORKING N DEP AT PHL, WITH ABOUT 10 ACFT UNDER CTL, 2 OF WHICH WERE UNTAGGED BY COMPUTER. WHEN I WAS GIVEN SEVERAL ACFT XING THE DEP PATHS AT DIFFERENT ALTS I STOPPED THE DEPS. AFTER THAT I BECAME SO INVOLVED WITH MOST OF THE ACFT THAT I DIDN'T SEE ATX X AND SMA Y APCHING THE MXE VOR SIMULTANEOUSLY AT 4000 FT UNTIL THEY WERE LESS THAN 3 MI APART. I XMITTED 'X CLB IMMEDIATELY AND MAINTAIN 5000 FT. TFC 9 O'CLOCK 2 MI, NBOUND, 4000, A CESSNA.' HE DID AND WAS AT 5000 FT ALMOST INSTANTANEOUSLY. ANOTHER CTLR WAS ALREADY WORKING Y AND TOLD ME THAT Y WAS MAINTAINING VISUAL SEPARATION WITH X.

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.