Date: 202109
Local time of day: 1201-1800
Location: SBA.TRACON, CA
Flight conditions: VMC
Light: Daylight
Aircraft: Small Aircraft
Operator: FBO
Operating under: Part 91
Flight plan: IFR
Mission: Training
Flight phase: Cruise
Airspace: Class E ZLA
ATC / advisory: TRACON SBA
Second aircraft: Small Aircraft
Reporter organization: FBO
Reporter function: Pilot Not Flying; Instructor
Reporter qualification: Flight Crew Commercial; Flight Crew Flight Instructor
Human factors: Communication Breakdown; Situational Awareness
Anomaly: Conflict Airborne Conflict; Conflict NMAC; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Air Traffic Control Issued Advisory / Alert; Flight Crew Took Evasive Action; Flight Crew Returned To Clearance
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: On an Instrument cross-country from ZZZ to SMX; we had just finished a descent from 8;000 ft. to 6;000ft. at ATC's direction as we passed over top of the RZS VOR. We were advised of traffic 12 o'clock; opposite direction. I can't recall if ATC said they were talking to the other aircraft or not; but we advised ATC that we were searching. We saw the other aircraft come up on our transponder at 500 ft. below and climbing; and I tagged the aircraft to monitor while continuing a visual scan. Once the aircraft got within 6nm; I instructed the student to remove his VLDs (View Limiting Device) and look for the traffic as well since the target had now moved to within 300 ft. and still indicating a climb on ADS-B.Approximately the time that the traffic target got within a 2 mile range; I finally saw the aircraft come into view. Their paint scheme was grey with blue; and made it hard to distinguish them against the mountainous terrain. They were exactly 12 o'clock and slightly low; maybe 200-300 ft. I took controls and initiated an evasive steep turn to the right; in accordance with 91.113. At roughly the same time; ATC called us to initiate another traffic advisory for traffic less than 2 miles. We replied that we had the traffic in sight and were deviating to avoid them. ATC then instructed to maintain visual separation; and we re-intercepted our course once we were well clear. My student said they were close enough to see the people in the other cockpit; and both of us felt that the encounter was way too close for comfort. The other aircraft did not appear to alter course to avoid our aircraft.I believe contributing factors may have been that the other pilot may not have been in contact with ATC; and that they were not flying a standard VFR/IFR altitude or were possibly using an inappropriate altimeter setting for their location. In the future; I will advise ATC that traffic is not in-sight sooner so that ATC can issue a vector to ensure adequate spacing.




Synopsis: Flight Instructor reported an airborne conflict occurred during cruise flight with another aircraft. Reportedly; the other aircraft was not in communication with ATC or flying a standard altitude for their direction of flight.