ATR aircraft and DH8 aircraft had near midair collision in sju class C airspace.

Attributes
ACN	418023
Time
Date	199810
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : sju airport : sju
State Reference	PR
Altitude	msl bound lower : 2500 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sju
Operator	common carrier : air carrier
Make Model Name	ATR Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 14
ASRS Report	418023
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : nmac non adherence : required legal separation non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action other
Consequence	Other
Miss Distance	horizontal : 0 vertical : 500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

The ATR was assigned 4000 ft and descended visually thinking he was on a visual approach clearance. He reported a TCASII RA 2 mi from the DHC8 while overtaking him descending out of 3000 ft. I was busy doing something else and did not notice it until he mentioned the RA. Once he said something, I vectored him around the aircraft. He then reported the aircraft in sight and was cleared for a visual approach and instructed to follow the DHC8.

Original NASA ASRS Text

Title: ATR ACFT AND DH8 ACFT HAD NMAC IN SJU CLASS C AIRSPACE.

Narrative: THE ATR WAS ASSIGNED 4000 FT AND DSNDED VISUALLY THINKING HE WAS ON A VISUAL APCH CLRNC. HE RPTED A TCASII RA 2 MI FROM THE DHC8 WHILE OVERTAKING HIM DSNDING OUT OF 3000 FT. I WAS BUSY DOING SOMETHING ELSE AND DID NOT NOTICE IT UNTIL HE MENTIONED THE RA. ONCE HE SAID SOMETHING, I VECTORED HIM AROUND THE ACFT. HE THEN RPTED THE ACFT IN SIGHT AND WAS CLRED FOR A VISUAL APCH AND INSTRUCTED TO FOLLOW THE DHC8.

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.