Pc-12 pilot reported coming close to another aircraft while descending into an airport.

Attributes
ACN	1565394
Time
Date	201807
Local Time Of Day	0601-1200
Place
Locale Reference	MVY.Airport
State Reference	MA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	PC-12
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Altitude Excursion From Assigned Altitude Deviation - Track / Heading All Types

Narrative:

While descending into mvy boston approach issued a traffic advisory at 11 o'clock and climbing; and issued a turn to heading of 150. Upon rolling out on the heading of 150 traffic was sighted directly in front of the aircraft and climbing. At that point the TCAS traffic alert went off and we immediately initiated a left turning climb to avoid climbing traffic converging on our altitude and 1/2 SM or less away. As soon as we initiated our maneuver boston also issued an immediate climb and turn to the left to avoid traffic. Estimated vertical separation was 250 ft feet and horizontal separation was 1;400 feet. Conflicting traffic maintained course and speed throughout the duration of this event. After the flight passengers inquired as to the reason for the abrupt maneuver and the (small airplane that was really close).

Original NASA ASRS Text

Title: PC-12 pilot reported coming close to another aircraft while descending into an airport.

Narrative: While descending into MVY Boston Approach issued a traffic advisory at 11 o'clock and climbing; and issued a turn to heading of 150. Upon rolling out on the heading of 150 traffic was sighted directly in front of the aircraft and climbing. At that point the TCAS traffic alert went off and we immediately initiated a left turning climb to avoid climbing traffic converging on our altitude and 1/2 SM or less away. As soon as we initiated our maneuver Boston also issued an immediate climb and turn to the left to avoid traffic. Estimated vertical separation was 250 ft feet and horizontal separation was 1;400 feet. Conflicting traffic maintained course and speed throughout the duration of this event. After the flight passengers inquired as to the reason for the abrupt maneuver and the (small airplane that was really close).

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.