Air carrier X TCASII RA descend from aircraft visibility separation in use had near midair collision...

Attributes
ACN	315500
Time
Date	199509
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : lga
State Reference	NY
Altitude	msl bound lower : 2500 msl bound upper : 2700
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : n90
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	ATR 42
Operating Under FAR Part	other : unknown
Flight Phase	cruise other
Route In Use	enroute : direct
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 : 10000 flight time type : 1400
ASRS Report	315500
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : overshoot conflict : nmac non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 500 vertical : 200
Supplementary
Primary Problem	Flight Crew Human Performance

Narrative:

Air carrier X from syr to lga was being radar vectored for an lda 'a' runway 22 approach into lga airport. We were level at 4000 ft and given a TA about a VFR aircraft at 1 O'clock and I believe at 3000 ft climbing and also converging. This aircraft was not currently talking to the controller who was working our flight. As we searched for this aircraft we were then given a clearance to dscnd to 3000 ft and shortly after that we were given the approach clearance to runway 22. The VFR aircraft then checked in with our controller and was advised of our position. The aircraft responded he has us insight and was instructed to maintain visual separation from us. Seconds later we got a TA on the TCASII system while we were descending and he was climbing and coming at us at about our 2 O'clock position. The TA showed this aircraft to be about 1 1/2 to 2 mi, 300 ft below us and climbing in our direction. A split second later we got a RA on this aircraft. RA instructed a descent of 1500 FPM. I started down and then the RA instructed an increase in rate to about 2000 FPM as we were passing about 3300 ft in our descent. We had to pass through our assigned 3000 ft altitude by about 300 ft before the TCASII resolved the conflict on this aircraft. By this time we had descended to an altitude of about 2700 ft when at a split second we got an RA on TCASII to climb at a rate of about 2000 FPM. As I did so and looked out the left side I saw an ATR 42 aircraft fly under us left to right at about only 200 ft to 300 ft separation. I believe the ATR 42 was VFR, transitioning under the lateral floor of the class B airspace at 2500 ft, cutting across the approach corridor en route to ewr airport. When we got the instruction to increase descent on the first I was a little hesitant to do so. If I had went to the full 2000 FPM increase (I only attained about 1800 FPM by the time first conflict was resolved) I do believe we would have hit the ATR.

Original NASA ASRS Text

Title: ACR X TCASII RA DSND FROM ACFT VIS SEPARATION IN USE HAD NMAC WITH VFR ACFT BELOW. EVASIVE ACTION TAKEN. SEE AND AVOID CONCEPT.

Narrative: ACR X FROM SYR TO LGA WAS BEING RADAR VECTORED FOR AN LDA 'A' RWY 22 APCH INTO LGA ARPT. WE WERE LEVEL AT 4000 FT AND GIVEN A TA ABOUT A VFR ACFT AT 1 O'CLOCK AND I BELIEVE AT 3000 FT CLBING AND ALSO CONVERGING. THIS ACFT WAS NOT CURRENTLY TALKING TO THE CTLR WHO WAS WORKING OUR FLT. AS WE SEARCHED FOR THIS ACFT WE WERE THEN GIVEN A CLRNC TO DSCND TO 3000 FT AND SHORTLY AFTER THAT WE WERE GIVEN THE APCH CLRNC TO RWY 22. THE VFR ACFT THEN CHKED IN WITH OUR CTLR AND WAS ADVISED OF OUR POS. THE ACFT RESPONDED HE HAS US INSIGHT AND WAS INSTRUCTED TO MAINTAIN VISUAL SEPARATION FROM US. SECONDS LATER WE GOT A TA ON THE TCASII SYS WHILE WE WERE DSNDING AND HE WAS CLBING AND COMING AT US AT ABOUT OUR 2 O'CLOCK POS. THE TA SHOWED THIS ACFT TO BE ABOUT 1 1/2 TO 2 MI, 300 FT BELOW US AND CLBING IN OUR DIRECTION. A SPLIT SECOND LATER WE GOT A RA ON THIS ACFT. RA INSTRUCTED A DSCNT OF 1500 FPM. I STARTED DOWN AND THEN THE RA INSTRUCTED AN INCREASE IN RATE TO ABOUT 2000 FPM AS WE WERE PASSING ABOUT 3300 FT IN OUR DSCNT. WE HAD TO PASS THROUGH OUR ASSIGNED 3000 FT ALT BY ABOUT 300 FT BEFORE THE TCASII RESOLVED THE CONFLICT ON THIS ACFT. BY THIS TIME WE HAD DSNDED TO AN ALT OF ABOUT 2700 FT WHEN AT A SPLIT SECOND WE GOT AN RA ON TCASII TO CLB AT A RATE OF ABOUT 2000 FPM. AS I DID SO AND LOOKED OUT THE L SIDE I SAW AN ATR 42 ACFT FLY UNDER US L TO R AT ABOUT ONLY 200 FT TO 300 FT SEPARATION. I BELIEVE THE ATR 42 WAS VFR, TRANSITIONING UNDER THE LATERAL FLOOR OF THE CLASS B AIRSPACE AT 2500 FT, CUTTING ACROSS THE APCH CORRIDOR ENRTE TO EWR ARPT. WHEN WE GOT THE INSTRUCTION TO INCREASE DSCNT ON THE FIRST I WAS A LITTLE HESITANT TO DO SO. IF I HAD WENT TO THE FULL 2000 FPM INCREASE (I ONLY ATTAINED ABOUT 1800 FPM BY THE TIME FIRST CONFLICT WAS RESOLVED) I DO BELIEVE WE WOULD HAVE HIT THE ATR.

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.

Air carrier X TCASII RA descend from aircraft visibility separation in use had near midair collision with VFR aircraft below. Evasive action taken. See and avoid concept.