Medium Large Transport
Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Flight Crew Last 90 Days 30; Flight Crew Total 7300; Flight Crew Type 60
ATC Issue All Types; Conflict NMAC
Flight Crew Took Evasive Action
Airspace Structure; Procedure
During arrival into TTN; weather CAVOK; approximately 15 miles southwest of TTN at 4;000 feet MSL we received a TCAS traffic alert followed several seconds later (less than 5 seconds) by a TCAS 'descend' RA. The traffic was a single engine aircraft that initially indicated on our TCAS approximately 100 feet above our 12 o'clock position and less than 3 miles. Estimate our aircraft missed the single engine traffic by approximately 200-300 feet. Pilot flying successfully maneuvered aircraft in response to RA; and pilot not flying acquired traffic visually during TCAS RA response maneuver. ATC (PHL Approach) did not alert us to traffic until execution of RA response; and pilot not flying subsequently reported the RA to ATC. Causal factors contributing to hazard incident include late ATC traffic advisory; and the short time interval between the TCAS traffic alert and Resolution Advisory. Suggest a review be conducted of the ATC radar during the incident to help identify additional contributing factors and determination of root cause(s).
Corporate jet First Officer reported a NMAC 15 NM southwest of TTN with a general aviation aircraft.