Small Aircraft
Flight Crew Private
Flight Crew Last 90 Days 40; Flight Crew Total 14000; Flight Crew Type 8000
Communication Breakdown
ATC Issue All Types; Conflict NMAC; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action; Flight Crew Returned To Clearance
Airspace Structure; Human Factors; Procedure
While cleared to the initial approach fix for STS; I was vectored 30 degrees right for traffic maneuvering at my eleven o'clock slightly high but erratically. Coincidentally the maneuvering airplane turned in the same direction initially. As we converged my GTN 70 warned me; I then saw the maneuvering airplane slightly above me at about eleven o'clock converging and avoided a potential collision by rapidly descending about 300 or 400 feet until clear when I climbed back to 5;000; all in good VMC. The Controller gave me a number to call about a 'possible deviation'. I called the number and talked with [a Controller]. He wondered why I didn't announce my avoidance maneuver. The reason was the need for an immediate and very rapid descent to avoid a potential collision. I thought the vector unsafe and was going to complain when I got the word to call and did. The key issue in the above seems to me to be who is responsible for traffic avoidance when on an IFR flight. Perhaps the Controller was busy and didn't notice the vector should have changed as I converged. There likely is some latency in the radar depiction. Further; I wonder why the Controller's software didn't supply a warning. Under the relevant FAR I took emergency measures to avoid a possible collision and did. There simply was not enough time to ask first.
GA pilot reported taking evasive action after ATC-assigned heading resulted in close conflict with another aircraft.