Less than standard separation between commuter and GA twin. Operation error.

Attributes
ACN	90565
Time
Date	198807
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ptw airport : phl
State Reference	PA
Altitude	msl bound lower : 7000 msl bound upper : 7000
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : phl tower : msp
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	climbout : intermediate altitude descent other
Route In Use	enroute : on vectors enroute airway : v29
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : departure
Qualification	controller : developmental
ASRS Report	90565
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance none taken : unable
Consequence	faa : investigated
Miss Distance	horizontal : 4200 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I am a deviation trnee at phl tower. I have certified through the control tower and currently training in the TRACON where I have certified on 3 radar positions. I was working modena sector (north departures), which I had been certified. It was a busy session including working overflts as well as departures. A commuter which departed phl was initially given a climb to 6000', then 7000' and a westerly heading for in trail spacing over the ptw VORTAC. A twin engine (light) was southbound on V29 south of ptw at 7000' overflying phl airspace. Both aircraft were IFR under radar contact. During course of events realizing sep may be lost I issued traffic to the commuter, subsequently descending and turning to avoid the twin. In turn I issued traffic and vector for the twin, no response. He was never switched to my frequency. Sep was lost and determined to be 7/10 mi latitude. The vol of traffic at the time was 9-10 aircraft. Basically they included jets and commuter propellers. I had taken action to alleviate some of my problem by stopping departures into my sector before this incident. But, basically I had reached my limit in airplanes and saw the situation a little late. I want you to know that I have taken full responsibility for this incident and hope you respect the intent of this letter.

Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN COMMUTER AND GA TWIN. OPERATION ERROR.

Narrative: I AM A DEV TRNEE AT PHL TWR. I HAVE CERTIFIED THROUGH THE CTL TWR AND CURRENTLY TRNING IN THE TRACON WHERE I HAVE CERTIFIED ON 3 RADAR POSITIONS. I WAS WORKING MODENA SECTOR (N DEPS), WHICH I HAD BEEN CERTIFIED. IT WAS A BUSY SESSION INCLUDING WORKING OVERFLTS AS WELL AS DEPS. A COMMUTER WHICH DEPARTED PHL WAS INITIALLY GIVEN A CLB TO 6000', THEN 7000' AND A WESTERLY HDG FOR IN TRAIL SPACING OVER THE PTW VORTAC. A TWIN ENG (LIGHT) WAS SBND ON V29 S OF PTW AT 7000' OVERFLYING PHL AIRSPACE. BOTH ACFT WERE IFR UNDER RADAR CONTACT. DURING COURSE OF EVENTS REALIZING SEP MAY BE LOST I ISSUED TFC TO THE COMMUTER, SUBSEQUENTLY DSNDING AND TURNING TO AVOID THE TWIN. IN TURN I ISSUED TFC AND VECTOR FOR THE TWIN, NO RESPONSE. HE WAS NEVER SWITCHED TO MY FREQ. SEP WAS LOST AND DETERMINED TO BE 7/10 MI LAT. THE VOL OF TFC AT THE TIME WAS 9-10 ACFT. BASICALLY THEY INCLUDED JETS AND COMMUTER PROPS. I HAD TAKEN ACTION TO ALLEVIATE SOME OF MY PROB BY STOPPING DEPS INTO MY SECTOR BEFORE THIS INCIDENT. BUT, BASICALLY I HAD REACHED MY LIMIT IN AIRPLANES AND SAW THE SITUATION A LITTLE LATE. I WANT YOU TO KNOW THAT I HAVE TAKEN FULL RESPONSIBILITY FOR THIS INCIDENT AND HOPE YOU RESPECT THE INTENT OF THIS LETTER.

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.