A320 experiences loss of separation with VFR mooney on arrival to lga.

Attributes
ACN	675223
Time
Date	200510
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : lga.airport
State Reference	NY
Altitude	msl single value : 13000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival star : mip
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zny.artcc
Operator	general aviation : personal
Make Model Name	M-20 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 250 flight time total : 13500 flight time type : 4200
ASRS Report	675223
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 270 flight time total : 10000 flight time type : 7000
ASRS Report	675225
Events
Anomaly	conflict : airborne critical inflight encounter other
Independent Detector	aircraft equipment : tcas
Resolutory Action	flight crew : took evasive action
Miss Distance	horizontal : 9000 vertical : 200
Supplementary
Problem Areas	ATC Human Performance Airspace Structure Aircraft Flight Crew Human Performance
Primary Problem	Airspace Structure

Narrative:

While at 13000 ft on MIP3 arrival into lga; ATC advised of a mooney 1 O'clock position and about 8 mi. We did not see the aircraft; but ATC advised that the mooney reported us in sight. We noticed an aircraft on TCAS at about 1 O'clock position and 5 mi; 200 ft above our altitude and descending. We still had not acquired the aircraft visually before we got a TCAS 'descend; descend.' the first officer (PF) performed the TCAS RA maneuver and descended at about 1100 FPM to 12300 ft. I (PNF) advised ATC of RA simultaneously and advised aircraft not in sight. Then we got a 'climb; climb now' RA which the first officer followed at about 400 FPM climb to 12600 ft. The TCAS then advised 'clear of conflict' and the first officer continued climb back to our assigned altitude of 13000 ft. The other aircraft passed about 1.5 laterally and within 200 ft vertically. ATC is required to separate IFR and participating VFR traffic. However; because the other aircraft reported us in sight; that relieved ATC of his responsibility of separation. This type of situation continues to occur and I believe it is imperative that ATC should be required to separate aircraft at night in these situations because the human eye is not well suited to maintain separation in these conditions.

Original NASA ASRS Text

Title: A320 EXPERIENCES LOSS OF SEPARATION WITH VFR MOONEY ON ARR TO LGA.

Narrative: WHILE AT 13000 FT ON MIP3 ARR INTO LGA; ATC ADVISED OF A MOONEY 1 O'CLOCK POS AND ABOUT 8 MI. WE DID NOT SEE THE ACFT; BUT ATC ADVISED THAT THE MOONEY RPTED US IN SIGHT. WE NOTICED AN ACFT ON TCAS AT ABOUT 1 O'CLOCK POS AND 5 MI; 200 FT ABOVE OUR ALT AND DSNDING. WE STILL HAD NOT ACQUIRED THE ACFT VISUALLY BEFORE WE GOT A TCAS 'DSND; DSND.' THE FO (PF) PERFORMED THE TCAS RA MANEUVER AND DSNDED AT ABOUT 1100 FPM TO 12300 FT. I (PNF) ADVISED ATC OF RA SIMULTANEOUSLY AND ADVISED ACFT NOT IN SIGHT. THEN WE GOT A 'CLB; CLB NOW' RA WHICH THE FO FOLLOWED AT ABOUT 400 FPM CLB TO 12600 FT. THE TCAS THEN ADVISED 'CLR OF CONFLICT' AND THE FO CONTINUED CLB BACK TO OUR ASSIGNED ALT OF 13000 FT. THE OTHER ACFT PASSED ABOUT 1.5 LATERALLY AND WITHIN 200 FT VERTICALLY. ATC IS REQUIRED TO SEPARATE IFR AND PARTICIPATING VFR TFC. HOWEVER; BECAUSE THE OTHER ACFT RPTED US IN SIGHT; THAT RELIEVED ATC OF HIS RESPONSIBILITY OF SEPARATION. THIS TYPE OF SITUATION CONTINUES TO OCCUR AND I BELIEVE IT IS IMPERATIVE THAT ATC SHOULD BE REQUIRED TO SEPARATE ACFT AT NIGHT IN THESE SITUATIONS BECAUSE THE HUMAN EYE IS NOT WELL SUITED TO MAINTAIN SEPARATION IN THESE CONDITIONS.

Data retrieved from NASA's ASRS site as of January 2009 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.