Regional Jet 900 (CRJ900)
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Training / Qualification
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action
Human Factors
While being vectored at 4000; NYC Approach advised us of VFR traffic at 3500'. We could not identify the aircraft; however we did receive a 'TCAS TA.' The TCAS showed that the VFR traffic was climbing and shortly thereafter we received a TCAS RA; 'level off.' The First Officer (FO) disconnected the autopilot and climbed approx. 200'-300'. I notified Approach that we were complying with an 'RA' and then we returned to our assigned altitude.  No further action was taken and the flight concluded without event.
CRJ-900 Captain reported the flying First Officer responded to a 'level off' RA by climbing several hundred feet.