Small aircraft X had near midair collision with small aircraft Y. See and avoid concept.

Attributes
ACN	187186
Time
Date	199108
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : bos
State Reference	MA
Altitude	msl bound lower : 3000 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bos
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	other
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
ASRS Report	187186
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument
Events
Anomaly	conflict : nmac
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 0 vertical : 100
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

I was working 2 sectors combined, small aircraft X was IFR training flight conducting an NDB approach at an uncontrolled airport. Small aircraft X was holding at 3000 MSL. There was multiple VFR aircraft in the area, small aircraft Y was on a converging course with the IFR aircraft indicating the same altitude. I issued the traffic 4 times to small aircraft X he had no joy with the VFR aircraft. I then issued traffic alert to the IFR aircraft suggesting he descend. He saw small aircraft Y pass directly overhead approximately 100 ft. If we had been talking to the VFR aircraft this would not happen.

Original NASA ASRS Text

Title: SMA X HAD NMAC WITH SMA Y. SEE AND AVOID CONCEPT.

Narrative: I WAS WORKING 2 SECTORS COMBINED, SMA X WAS IFR TRAINING FLT CONDUCTING AN NDB APCH AT AN UNCTLED ARPT. SMA X WAS HOLDING AT 3000 MSL. THERE WAS MULTIPLE VFR ACFT IN THE AREA, SMA Y WAS ON A CONVERGING COURSE WITH THE IFR ACFT INDICATING THE SAME ALT. I ISSUED THE TFC 4 TIMES TO SMA X HE HAD NO JOY WITH THE VFR ACFT. I THEN ISSUED TFC ALERT TO THE IFR ACFT SUGGESTING HE DSND. HE SAW SMA Y PASS DIRECTLY OVERHEAD APPROX 100 FT. IF WE HAD BEEN TALKING TO THE VFR ACFT THIS WOULD NOT HAPPEN.

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.