A319
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Communication Breakdown
ATC Issue All Types; Conflict Airborne Conflict
Flight Crew Took Evasive Action
Human Factors; Procedure
While on the FLOSI3 RNAV arrival into Newark after passing the CRANK intersection; ATC vectored us off the arrival heading 230 and assigned us to descend from 7000 MSL to 4000 MSL. The vector placed us about 5 miles behind a VFR aircraft at 3500 MSL. The VFR aircraft was also heading roughly 230. We were overtaking the VFR aircraft with approximately 40 knots of overtake. There was a 600' broken cloud deck from 3500' to 4100' MSL which kept us IMC. ATC pointed out the VFR traffic but we told them we were not visual (IMC). At roughly 1 to 2 miles from the VFR traffic and leveling at 4000' our TCAS showed the traffic climbing. At inside of a mile (estimated based on TCAS); I perceived an impending conflict based on the TCAS trend and our over-take. I turned off the autopilot and initiated an aggressive climb. Moments after initiating the climb; the TCAS RA aural alert sounded with an initial descend command followed immediately by a climb command. I followed the climb command with the vertical speed in the green until 'clear of conflict' was heard which happened at about 4500' MSL. The Captain informed ATC that we were climbing as a result of the RA. ATC acknowledged and assigned us back down to 4000' MSL. The rest of the approach and landing was uneventful.
First Officer reported executing an aggressive RA TCAS command in IMC following ATC's vectors off the assigned STAR.