Date: 201910
Local time of day: 1201-1800
Location: PLU.Airport, WA
Flight conditions: VMC
Light: Daylight
Aircraft: Super King Air 300
Operator: Corporate
Operating under: Part 91
Flight plan: None
Mission: Passenger
Flight phase: Descent
ATC / advisory: CTAF PLU; TRACON S46
Reporter organization: Corporate
Reporter function: Captain; Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Anomaly: Conflict NMAC; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft TA; Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Airspace Structure; Procedure; Human Factors
Primary problem: Human Factors

Narrative: Descending VFR (Visual Flight Rules) in good VMC (Visual Meteorological Conditions) conditions into a non-towered field that I am very familiar with; also very familiar with traffic density in this area. Approximately 10 miles to the northeast I was making my continued descent to traffic pattern altitude and listening to both the local TRACON (Terminal Radar Control Facility) frequency and CTAF (Common Traffic Advisory Frequency) to keep a big picture of traffic in the area; runway in use; etc. I was not receiving VFR radar advisories due to controller workload (was told after initial request on departure just a few minutes before to 'call back in 10 minutes') but monitoring the frequency as I was under Class Bravo airspace. Our TCAS (Traffic Collision Avoidance System) system presented multiple targets between us and the airport but I was focusing specifically on 2 as they were both within 100-200 ft. of our altitude and between 10 and 2 o'clock at 2-3 miles. The 10 o'clock target was slightly further away and moving left to right; the 2 o'clock target was moving very slightly right to left and slightly closer. I acquired both aircraft visually at approximately 2 miles or less and made a slight left turn. Both targets had apparent relative motion so I was not overly concerned about a collision threat. I received an aural TCAS TA (Traffic Advisory) on the aircraft to our right side as 'traffic 1 o'clock; same altitude; less than 1 mile' or very similar. Within a few seconds I also received 'traffic 2 o'clock; same altitude; less than 1 mile' (or similar). Given that I had the 2 aircraft (now at 12 o'clock and 1 o'clock in sight) I made the mistake of assuming these were the targets referenced by TCAS; the inaccuracy due to refresh rates in the system. As the 1 o'clock traffic moved to 12 o'clock and began to pass overhead within a few hundred ft.; I moved my head so as to see around the center post of the cockpit windshield to reacquire the more distant airplane moving left to right. I was immediately presented with a full frontal view of the wingman of the airplane that had just passed overhead. Based on the relative motion of the 'new' target airplane I immediately knew we were not going to hit; but it was going to be a close pass. I estimate we were 100-200 ft. apart vertically as he passed behind. I did not receive an RA ('descend'; etc.) though I started a slightly increased descent as the lead aircraft passed overhead. I never heard any calls from Approach to those aircraft so I assume they were not receiving radar advisories as well. Couple good debrief points for sure. Luckily; I feel I had done a couple proactive things based on experience in this area: I had slowed down (approx. 150 KIAS and slowing) as I got close to 10 miles and nearing 2000 ft. AGL (Above Ground Level). All lights were on. Eyes were out; primary avoidance based on eyeballs and not inside staring at a screen (though the TCAS presentation helped initially tremendously.)Looking back; wish I would have pushed a little harder for flight following despite being told to wait based on controller workload. (I still believe based on what I was hearing on frequency that they were too busy. Having a second set of radar eyes wouldn't have let us get that close however.) I was COMPLETELY surprised by the second aircraft (wingman) in echelon or loose trail with lead. Kind of shudder to think if I wouldn't have started the slight descent as lead went over how closely I would have passed from the wingman. I'm glad Big Sky Theory worked today but I definitely put a couple more rocks in the experience bucket. I'm also totally re-evaluating whether I want to continue to fly VFR under Class Bravo with or without flight following; or whether it's better to simply file IFR and use the system to my advantage as long as possible despite the weather (beautiful CAVU (Clear And Visibility Unlimited) in this case.)




Synopsis: BE30 Pilot reported a near miss with another aircraft on descent to airport.