Date: 201504
Local time of day: 1201-1800
Location: N90.TRACON, US
Flight conditions: VMC
Light: Daylight
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B NYC; Class E ZNY
ATC / advisory: TRACON N90
Second aircraft: Small Transport; Low Wing; 2 Recip Eng
Reporter organization: Air Carrier
Reporter function: Other / Unknown
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Conflict NMAC
Detector: Automation Aircraft RA; Person Air Traffic Control; Person Observer; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action
Contributing factors: Human Factors; Airspace Structure; Procedure
Primary problem: Ambiguous

Narrative: I was sitting in the cockpit jumpseat at 6000 FT ALT on a heading given by approach control. We first got a TCAS alert. I saw the conflicting aircraft at +200 FT on TCAS. Next we got an Resolution Advisory (RA) to descend. Captain  descended. First Officer happened to be on the radio talking to approach control and told the controller we were descending for an RA alert. Controller seemed to know the situation because he said 'Aircraft Y is descending' Then we got another RA to climb. Right after that the captain saw the conflicting aircraft and made a sharp right turn to avoid. I saw Aircraft Y make a sharp right turn also. Conflict avoided.


Second narrative: This report concerns a near miss event. I was the FO and pilot monitoring (PM) during the flight; the Captain (CA) was the pilot flying (PF). We also had a company FO riding on the jumpseat.Our flight was maintaining level flight at 6000 FT on a heading 060 as assigned by NY Approach in a base position some 20+ miles NW of EWR. Autopilot and autothrottles were both engaged. We were receiving vectors for the ILS 22L; but had not yet been turned by ATC towards TEB or the localizer.I initially noticed a target on the TCAS just a few miles ahead and 400 FT above us. I took note of the potential traffic and started searching ahead. There was a hazy cloud layer right around 6000 FT which meant visibility at that altitude was poor; though the slant range visibility looking well above or below our 6000 FT height was better.Very shortly after I noticed the target; we received a Traffic Advisory (TA) traffic alert. Both the CA and I were searching ahead for a visual on the traffic but we did not have visual contact yet. At this point we didn't know anything about what type of aircraft was ahead or what they were doing. While searching for the TA target; we received a radio call from NY approach pointing out the traffic. As best as I recall; ATC called the traffic as Aircraft Y at 12 o'clock; opposite direction; and at our altitude. While still looking outside; I keyed the mic to acknowledge and say we were searching. While I was making that transmission; we received an Resolution Advisory (RA) to Descend. The CA took manual control and quickly started descending. I added to my ATC reply that we were descending for an RA. NY approach then replied that the Aircraft Y traffic was also descending.Around this time; the CA visually acquired the traffic and shortly thereafter I also visually acquired the traffic. The Aircraft Y traffic appeared in the upper left corner of my (FO) windshield - he appeared to be above us in altitude and appeared to be banking to (his) right. Immediately after visually acquiring the traffic; the CA continued the descent. By this point; the RA had reversed and was instructing a climb. The CA verbalized that he wasn't going to climb because it appeared a climb would take us into the other aircraft.After Aircraft Y passed by our left side and just above us; we did eventually climb and went up to about 6400 FT or so. I clarified with ATC about what altitude and heading they wanted us to return to and we continued on with the assigned vectors for the approach. The CA did key the mic and ask for a phone number; which we copied from ground control after landing. By my estimate; I'd say Aircraft Y was 1/2 mile ahead and about 200 FT above our altitude (we were descending at the time) when I first acquired him visually. I know he passed closer than that to our aircraft but since he passed on aircraft left; I don't have a good estimate for his closest point of approach. But; the entire encounter was way too close for normal safe operations.After blocking in at the gate and finishing Parking checklist; we completed a debrief between ourselves and the jumpseater to calm down a bit. We also talked to several of the Flight Attendants (FA) and gave them an explanation of what had occurred. They indicated that the maneuvers had unnerved the passengers. The Lead FA had the presence of mind to make a brief PA to reassure the pax while we were still vectoring for the approach. I regret that we were unable to provide any explanation to the passengers; but the workload and adrenaline was high and it was still a very busy period vectoring for the approach and landing.


Synopsis: The anatomy of a NMAC from the perspective of both flight crews and the N90 Controller involved.