Date: 202004
Local time of day: 0601-1200
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Jet/Long Ranger/206
Operator: Corporate
Operating under: Part 91
Flight plan: None
Mission: Traffic Watch
Flight phase: Cruise
Second aircraft: Cessna 400
Reporter organization: Contracted Service
Reporter function: Single Pilot; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown
Anomaly: ATC Issue All Types; Conflict NMAC; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Aircraft X departs ZZZ to move on station for orbits at Cal State University (VPZZZ). Aircraft X reports on station; as requested by tower and orbits at approximately 1;100 ft. to 1;300 ft. MSL.Aircraft X hears a call from Aircraft Y inbound to ZZZ and hears the Tower instruct him/her (paraphrasing): 'Enter a 4-mile right base.... there is a helicopter orbiting at Cal-State at [altitude]'.There are various exchanges between Tower; Aircraft Y and Aircraft X where Tower reports position of Aircraft Y to Aircraft X and vice versa. On each of these call Aircraft X reports 'Looking...'.At one point Tower calls Aircraft X and reports that Aircraft Y 'is one mile north'; Aircraft X reports back 'Looking' again. But Aircraft Y reports 'traffic in sight [ I believe he/she actually said 'Helicopter in sight''.Upon rounding the orbit in a direction where I could see north; Aircraft Y ends up coming visually through the bottom right chin bubble of the helicopter and we almost were directly over him by the time he was in line with the nose of the helicopter. Separation was about 500 ft. per the pilot. Passenger in back who could have only seen the airplane out his left window; (flying in a direction away from Aircraft X) says it was 300 ft.Neither pilot of either aircraft took any evasive action - it was clear at least to me that we would not hit. But it was closer than expected. And Aircraft Y was not where it was to be expected.Based on Tower's initial instruction (enter a 4-mile base); I was expecting Aircraft Y to pass east of my position and then turn straight-in to the runways. In other words; passing me at a distance further away from the airport than I was. Instead; Aircraft Y decided to 'cut the corner' at about 3 miles and make a 45 entry to final. Aircraft Y effectively tried to pass between me and the airport instead.I think it was poor judgement on the part of the Aircraft Y pilot to turn in towards the runways at Cal State; rather than continue until he/she was perpendicular to the runways before turning final. I believe that the intent from Tower; right from the first call to Aircraft Y was specifically designed to avoid exactly the situation that happened. I do not believe Aircraft Y understood the implication of the initial call up from the tower (Enter 4-mile right base.... there is a helicopter at Cal State...)Perhaps Tower could have emphasized. 'Enter a 4-mile base to final and square the base; or pass east of the helicopter before turning final')Upon analysis afterwards on the ground; Aircraft Y landed at ZZZ at XA:24 on [date]. Aircraft X lifted ZZZ at XA:15 and landed at XA:36.




Synopsis: Helicopter pilot reported that a misunderstanding between Tower and a fixed wing aircraft resulted in a NMAC.