Narrative:

The captain was the PF as we were being vectored for the ILS runway 22 at lga. We were given a final intercept heading and told to maintain 3000 ft. In the turn, I was scanning for traffic. After becoming established on the intercept heading, we received an RA for an immediate climb. I looked at the TCASII and saw a traffic symbol at -100 ft. To comply with the RA, the captain initiated a pull-up of approximately 2500 FPM (while asking for 'maximum power'). We had no visual contact with the aircraft. At this time, the captain also heard a clearance from approach control to climb to 4000 ft. I made 1 attempt to call them about our actions with no reply. I was delayed in a follow-up call due to scanning for traffic and flight path monitoring duties. I then looked up and at our 12 O'clock position saw jet traffic moving right to left about 1000 ft above us and now diverging. Once we visually verified there was no conflict with this traffic, and in order to comply with our previous instruction of localizer intercept, and to remain clear of unknown airspace ahead, the captain initiated a turn of approximately 15 degrees behind the jet traffic. Once level at 4000 ft, the captain called for 'autoplt on' and I again called approach control with no response due to frequency congestion. After a second attempt to contact ATC, we were instructed to turn right heading 360 degrees and maintain 4000 ft. The captain then initiated a right turn (30 degree bank) to the new heading, at which point we were given a frequency change to another controller. He then gave us vectors back around for another ILS approach, which proceeded without incident. We surmised that the traffic from below could have been a VFR aircraft in a climb planning to level off under the overlying airspace. The floor of class B airspace in the area varies from 1500 ft to 3000 ft. It would seem to me to be necessary to lower this airspace in the area of the extended centerline of runway 22, as this obviously is a very serious threat to airline safety. According to a flight attendant spoken to after the flight who was in the rear of the aircraft during the incident, several passenger saw a 'light plane' in close proximity just below and behind our right wing after we had initiated the pull-up. The TCASII was an excellent tool in helping us avoid a potentially deadly situation.

Related reports:

Google
 

Original NASA ASRS Text

Title: TCASII PREVENTS AN NMAC IN LGA CLASS B AIRSPACE.

Narrative: THE CAPT WAS THE PF AS WE WERE BEING VECTORED FOR THE ILS RWY 22 AT LGA. WE WERE GIVEN A FINAL INTERCEPT HDG AND TOLD TO MAINTAIN 3000 FT. IN THE TURN, I WAS SCANNING FOR TFC. AFTER BECOMING ESTABLISHED ON THE INTERCEPT HDG, WE RECEIVED AN RA FOR AN IMMEDIATE CLB. I LOOKED AT THE TCASII AND SAW A TFC SYMBOL AT -100 FT. TO COMPLY WITH THE RA, THE CAPT INITIATED A PULL-UP OF APPROX 2500 FPM (WHILE ASKING FOR 'MAX PWR'). WE HAD NO VISUAL CONTACT WITH THE ACFT. AT THIS TIME, THE CAPT ALSO HEARD A CLRNC FROM APCH CTL TO CLB TO 4000 FT. I MADE 1 ATTEMPT TO CALL THEM ABOUT OUR ACTIONS WITH NO REPLY. I WAS DELAYED IN A FOLLOW-UP CALL DUE TO SCANNING FOR TFC AND FLT PATH MONITORING DUTIES. I THEN LOOKED UP AND AT OUR 12 O'CLOCK POS SAW JET TFC MOVING R TO L ABOUT 1000 FT ABOVE US AND NOW DIVERGING. ONCE WE VISUALLY VERIFIED THERE WAS NO CONFLICT WITH THIS TFC, AND IN ORDER TO COMPLY WITH OUR PREVIOUS INSTRUCTION OF LOC INTERCEPT, AND TO REMAIN CLR OF UNKNOWN AIRSPACE AHEAD, THE CAPT INITIATED A TURN OF APPROX 15 DEGS BEHIND THE JET TFC. ONCE LEVEL AT 4000 FT, THE CAPT CALLED FOR 'AUTOPLT ON' AND I AGAIN CALLED APCH CTL WITH NO RESPONSE DUE TO FREQ CONGESTION. AFTER A SECOND ATTEMPT TO CONTACT ATC, WE WERE INSTRUCTED TO TURN R HDG 360 DEGS AND MAINTAIN 4000 FT. THE CAPT THEN INITIATED A R TURN (30 DEG BANK) TO THE NEW HDG, AT WHICH POINT WE WERE GIVEN A FREQ CHANGE TO ANOTHER CTLR. HE THEN GAVE US VECTORS BACK AROUND FOR ANOTHER ILS APCH, WHICH PROCEEDED WITHOUT INCIDENT. WE SURMISED THAT THE TFC FROM BELOW COULD HAVE BEEN A VFR ACFT IN A CLB PLANNING TO LEVEL OFF UNDER THE OVERLYING AIRSPACE. THE FLOOR OF CLASS B AIRSPACE IN THE AREA VARIES FROM 1500 FT TO 3000 FT. IT WOULD SEEM TO ME TO BE NECESSARY TO LOWER THIS AIRSPACE IN THE AREA OF THE EXTENDED CTRLINE OF RWY 22, AS THIS OBVIOUSLY IS A VERY SERIOUS THREAT TO AIRLINE SAFETY. ACCORDING TO A FLT ATTENDANT SPOKEN TO AFTER THE FLT WHO WAS IN THE REAR OF THE ACFT DURING THE INCIDENT, SEVERAL PAX SAW A 'LIGHT PLANE' IN CLOSE PROX JUST BELOW AND BEHIND OUR R WING AFTER WE HAD INITIATED THE PULL-UP. THE TCASII WAS AN EXCELLENT TOOL IN HELPING US AVOID A POTENTIALLY DEADLY SIT.

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.