2011-10 · NASA ASRS report 976132
N90 Controller described a loss of separation event when traffic responding to a TCAS RA climbed and conflicted with IFR traffic in another controller's sector; the reporter recommending extensions to the Class B.
I was in the process of decombining the arrival positions. It was a clear VFR day and it was a 'target-rich' environment' with many VFRs operating on their own below the Class B floor. I had just put Aircraft X; a Citation arriving HPN from the West; on a vector to the final when I noticed a 1200 code indicating 2;700'. I issued the traffic then momentarily switched my attention Eastward to the other arrivals. Shortly thereafter; Aircraft X announced he was executing a TCAS RA climb. As I looked back I saw that he was climbing into Aircraft Y; a NW-bound Light Transport under control of another controller. The pilot initiated a TCAS climb before informing me and separation with Aircraft Y was lost immediately. I issued Aircraft Y traffic right away but I saw Aircraft X's Mode C indicate 3;800 before descending again. Recommendation; we have many close calls every day with VFR aircraft operating one or two hundred feet above or below the Class B airspace around the NY Metro area. Extending the 20-mile ring of the NY Class B airspace from the surface to 10;000' MSL would improve safety.
I was working combined positions. I had Aircraft Y on a vector Northwest bound at 4000 IFR to TEB. I also had a VFR C172 at 2500 Westbound. An adjacent controller had Aircraft X join a 070 heading to the ILS 16 at HPN. The VFR C172 showed 26 altitude in scratch pad. I gave him the traffic call of Aircraft X. I also issued the traffic of Aircraft X to Aircraft Y as their targets might merge. The c172 caused the TCAS of Aircraft X to issue a resolution alert causing him to climb to 3800 in close proximity to Aircraft Y. He quickly descended to about 3000 but separation was clearly lost prior to that. Recommendation; the TCAS seemed to only consider the proximity to the VFR aircraft and did not factor in the oncoming IFR traffic. The TCAS needs better processing.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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