Reporter alerted by TCASII RA sees and avoids potential conflict while on radar vector to lga.

Attributes
ACN	279386
Time
Date	199408
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : lga
State Reference	NY
Altitude	msl bound lower : 7500 msl bound upper : 8000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	enroute : on vectors enroute airway : n90
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Cessna Single Piston Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 8500 flight time type : 2000
ASRS Report	279386
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action flight crew : returned to intended course or assigned course
Consequence	Other
Miss Distance	horizontal : 3000 vertical : 200
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On assigned heading of 090 degrees to intercept milton 8 arrival between nanci and proud intxns (lga 225 degrees radial). Cleared from 9000-7000 ft in descent at approximately 8000 ft. Received RA on TCASII command climb. Climbed to 8000 ft when I saw cessna 1XX sbound at approximately 7500 ft 1/4 to 1/2 mi to left. At that time lga approach called traffic at 10-11 O'clock at 7400 ft. After cessna passed to south, I continued descent to 7000 ft. I do not believe other aircraft saw us at any time. He appeared to be at a legal VFR altitude. Maneuver to arrest descent (1000 FPM) and climb back to approximately 8000 ft was without disturbance in cabin. Incident lasted 15-20 seconds. ATC was advised of 'RA.' no comment received. Continued vectors to approach and land on runway 13 at lga at approximately XA06 local. I don't know of anything we could have done to avoid the incident. TCASII helped avoid a potentially catastrophic incident.

Original NASA ASRS Text

Title: RPTR ALERTED BY TCASII RA SEES AND AVOIDS POTENTIAL CONFLICT WHILE ON RADAR VECTOR TO LGA.

Narrative: ON ASSIGNED HDG OF 090 DEGS TO INTERCEPT MILTON 8 ARR BTWN NANCI AND PROUD INTXNS (LGA 225 DEGS RADIAL). CLRED FROM 9000-7000 FT IN DSCNT AT APPROX 8000 FT. RECEIVED RA ON TCASII COMMAND CLB. CLBED TO 8000 FT WHEN I SAW CESSNA 1XX SBOUND AT APPROX 7500 FT 1/4 TO 1/2 MI TO L. AT THAT TIME LGA APCH CALLED TFC AT 10-11 O'CLOCK AT 7400 FT. AFTER CESSNA PASSED TO S, I CONTINUED DSCNT TO 7000 FT. I DO NOT BELIEVE OTHER ACFT SAW US AT ANY TIME. HE APPEARED TO BE AT A LEGAL VFR ALT. MANEUVER TO ARREST DSCNT (1000 FPM) AND CLB BACK TO APPROX 8000 FT WAS WITHOUT DISTURBANCE IN CABIN. INCIDENT LASTED 15-20 SECONDS. ATC WAS ADVISED OF 'RA.' NO COMMENT RECEIVED. CONTINUED VECTORS TO APCH AND LAND ON RWY 13 AT LGA AT APPROX XA06 LCL. I DON'T KNOW OF ANYTHING WE COULD HAVE DONE TO AVOID THE INCIDENT. TCASII HELPED AVOID A POTENTIALLY CATASTROPHIC INCIDENT.

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.