Local controller issues vectors and altitude change to air carrier to avoid VFR crossing traffic.

Attributes
ACN	552422
Time
Date	200207
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zzz.tracon
State Reference	US
Altitude	msl single value : 9000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : zzz.tracon
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Route In Use	arrival star : zzzzz2
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : zzz.tracon
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Plan	VFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller military : 3 controller non radar : 3 controller radar : 16
ASRS Report	552422
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued advisory controller : issued new clearance
Consequence	faa : reviewed incident with flight crew
Miss Distance	vertical : 500
Supplementary
Problem Areas	Airspace Structure Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

I was working the arrival position at ZZZ approach. I was working a B727 inbound on the ZZZZZ2 arrival. He was at 10000 ft and I descended him to 7000 ft at the normal point. About 20 seconds later, I noticed a target with a limited non discrete data tab (1200) with mode C indicating 8300 ft. I then issued aircraft X 9000 ft and issued VFR traffic. Aircraft X did not see the traffic until it was at his 3 O'clock position and approximately 1 mi. I forgot to mention I also vectored aircraft X off the arrival route to avoid overflying over the unverified target. In our environment class C airspace the VFR aircraft was in the right to be where he was, but I feel if he were required to participate in VFR advisories, then I would have known and verified his altitude. At the time of the incident I was only working 2 aircraft. If I had been working moderate traffic, I could have not observed the VFR and the 2 aircraft could have gotten closer than they did. The X aircraft that fly into ZZZ aren't presently required to be equipped with TCASII so the pilot had no assistance in finding VFR's except for ATC. This time the system worked, but it could have worked better had I been talking to both of them.

Original NASA ASRS Text

Title: LCL CTLR ISSUES VECTORS AND ALT CHANGE TO ACR TO AVOID VFR XING TFC.

Narrative: I WAS WORKING THE ARR POS AT ZZZ APCH. I WAS WORKING A B727 INBOUND ON THE ZZZZZ2 ARR. HE WAS AT 10000 FT AND I DSNDED HIM TO 7000 FT AT THE NORMAL POINT. ABOUT 20 SECONDS LATER, I NOTICED A TARGET WITH A LIMITED NON DISCRETE DATA TAB (1200) WITH MODE C INDICATING 8300 FT. I THEN ISSUED ACFT X 9000 FT AND ISSUED VFR TFC. ACFT X DID NOT SEE THE TFC UNTIL IT WAS AT HIS 3 O'CLOCK POS AND APPROX 1 MI. I FORGOT TO MENTION I ALSO VECTORED ACFT X OFF THE ARR RTE TO AVOID OVERFLYING OVER THE UNVERIFIED TARGET. IN OUR ENVIRONMENT CLASS C AIRSPACE THE VFR ACFT WAS IN THE RIGHT TO BE WHERE HE WAS, BUT I FEEL IF HE WERE REQUIRED TO PARTICIPATE IN VFR ADVISORIES, THEN I WOULD HAVE KNOWN AND VERIFIED HIS ALT. AT THE TIME OF THE INCIDENT I WAS ONLY WORKING 2 ACFT. IF I HAD BEEN WORKING MODERATE TFC, I COULD HAVE NOT OBSERVED THE VFR AND THE 2 ACFT COULD HAVE GOTTEN CLOSER THAN THEY DID. THE X ACFT THAT FLY INTO ZZZ AREN'T PRESENTLY REQUIRED TO BE EQUIPPED WITH TCASII SO THE PLT HAD NO ASSISTANCE IN FINDING VFR'S EXCEPT FOR ATC. THIS TIME THE SYS WORKED, BUT IT COULD HAVE WORKED BETTER HAD I BEEN TALKING TO BOTH OF THEM.

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.