Small Transport
Flight Crew Instrument; Flight Crew Private; Flight Crew Multiengine
Flight Crew Last 90 Days 41; Flight Crew Total 3100; Flight Crew Type 1100
Situational Awareness; Human-Machine Interface; Distraction; Communication Breakdown
Conflict NMAC
Flight Crew Took Evasive Action
Human Factors
On initial approach to TRM I was announcing the arrival quite often and very diligently; in a descent of approximately 1;600 feet per minute another plane was observed on the ADS-B and was in sight. I continued the descent to fly well under the plane which was obviously VFR and as I approached the plane it turned into me with a sharp turn. The TCAS had a TA but not an RA as I had descended well below the other plane. The other plane must not have been monitoring the UNICOM or monitoring their traffic ADS-B.I realize now that I should have changed course at an earlier time; to give a much wider birth to the crossing plane. Also; I can not take into account other pilots listening to the CTAF or UNICOM frequency for area traffic. In addition; as I approached the airport to fly over and enter a left downwind; another plane was spotted that had just flown over the field with no announcements. VFR traffic in this area are not listening or announcing their intentions in the airport environment.
GA pilot flying to non-towered TRM airport reported an NMAC with another aircraft in the pattern.