Date: 201511
Local time of day: 1201-1800
Location: HPN.Airport, NY
Flight conditions: VMC
Light: Daylight
Aircraft: Small Transport
Operator: Air Taxi
Operating under: Part 135
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class D HPN
ATC / advisory: Tower HPN
Second aircraft: Small Aircraft
Reporter organization: Air Taxi
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Commercial; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Distraction; Situational Awareness
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Conflict NMAC; Deviation - Altitude Excursion From Assigned Altitude
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action
Contributing factors: Airport; Airspace Structure; Human Factors
Primary problem: Human Factors

Narrative: New York Approach cleared us for a visual approach to Runway 34 at KHPN while on a right base over the shoreline; number two behind Aircraft Z on final that we had in sight. When we checked in with the tower; the controller cleared us to land number three behind Aircraft Z (#1) and a piston landing runway 29 (#2) which the First Officer located and I confirmed as in sight. I let the Auto Pilot fly the airplane onto the LOC/GS; maintaining about 120 KEAS for spacing. We noted both Aircraft Z and the piston land and rollout. At approx 700 AGL Aircraft Y appeared at an intercept angle and altitude on a right base to 34 to our right. At approx the same time; the tower asked that aircraft if they had us in sight to sequence behind and the pilot replied negative and the controller instructed him to execute an immediate climbing right turn. Simultaneously; I disconnected the Auto Pilot and descended below the GS in order to avoid a collision. The other airplane did not turn before passing directly overhead our airplane; with the controller noting as much on the frequency. Our TAS system did not generate an alert. Once we passed the conflict; I recaptured the GS and flew the rest of the approach by hand; landing without further incident. As we were taxiing; the incident aircraft landed (identified by voice on the frequency) and we noted his tail number as he rolled out on runway 34.


Second narrative: While on a passenger carrying (part 135) visual approach to land Runway 34 at KHPN; the pilot flying (PIC) was forced to descend below the visual glide path to avoid being hit by Aircraft Y who had turned right base without seeing us on final. Once the conflict had been averted and Aircraft Y passed overhead; the PF rejoined the glide path and landed without further incident. During the approach; the tower had queried the Aircraft Y pilot about whether or not he had visual contact with us and he replied in the negative. The tower instructed the pilot to execute an immediate climbing right turn; which he failed to comply with and continued on the collision course.The pattern was busy and when we were cleared to land; we were sequenced as #3 to the field with Aircraft Z (#1) ahead of us on final to Runway 34 and a piston single on runway 29 (#2); which both the PF and myself had in sight. The Aircraft Y pilot's lack of situational awareness and the tower's failure to sequence the traffic contributed to this near miss. Strangely; we did not receive a traffic alert from our on-board system.


Synopsis: The flight crew of a light jet aircraft reported having to take evasive action while on final approach due to the encroachment of a general aviation aircraft. After deviating from the glide scope the crew was able to reacquire the glide slope and land successfully.