Date: 202107
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: SA-227 AC Metro III
Operator: Air Taxi
Operating under: Part 135
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Initial Approach
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Second aircraft: Any Unknown or Unlisted Aircraft Manufacturer
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine
Human factors: Workload; Confusion; Distraction; Communication Breakdown; Time Pressure
Second reporter function: Pilot Flying; Captain
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Contributing factors: Human Factors; Procedure; Airspace Structure
Primary problem: Procedure

Narrative: While supporting a Metro pilot as a non-acting crew member on the ZZZ-ZZZZ run who was unfamiliar with the specifics; we were returning to ZZZ and found the airplane in a near-miss with VFR Traffic. The pilot; was instructed to fly direct to the IAF. The controller alerted us about VFR traffic; later instructing to expedite descent to 4;300 feet. I continued to watch for traffic as it was on my side of the aircraft. I found the traffic and alerted the Captain that it was at the same altitude; heading in our direction of flight. Being unfamiliar with the aircraft I'm not sure if there is proper TCAS; but we received an alert and immediately descended to avoid the near-miss with VFR traffic. The pilot flying then told the Approach Controller his action and intent; and the controller repeated twice 'below MVA (Minimum Vectoring Altitude) climb to 4;300 feet but we were unable due to the VFR traffic we were avoiding. After successfully avoiding the traffic the Captain climbed to 4;300 feet and continued the approach. I saw the VFR/colliding traffic at the airplane's 3 o'clock; the side of the airplane I could visually see from my observation seat. Lack of vectoring instruction from ATC for two airplanes on a collision course. Captain immediately descended to avoid collision with VFR traffic. IFR traffic and VFR traffic needs better observation from ATC. Though I was a non-acting crew member on this flight the Captain and I worked as a team and executed proper CRM to avoided a mid-air collision.


Second narrative: I was operating Aircraft X to ZZZ; as the Captain and Pilot Flying. Onboard I had a Brasilia First Officer; who flew down to ZZZZ with me to assist with customs and all the paperwork associated with the run. ZZZ-ZZZZ was his regular run; and I was covering it for the day. The additional crew member was not an active crew member during the leg; but he was on headset with me helping to monitor the flight. It was towards the end of the flight; and we were being vectored by Approach. We were flying towards the Initial Approach Fix for the ILS Approach and descending to 4;300 feet. During the descent; ATC called out VFR traffic to our 3 o'clock position several miles away; at an altitude of 4;500 feet. During the descent; ATC has also told us to expedite our descent. Initially; we saw traffic in that direction and called 'in sight' to ATC; but I quickly realized we had identified a 737 climbing; not the VFR traffic we were looking for. I decided to use the First Officer and asked him to continue to look for the VFR traffic. He told me he had it in sight; and he helped me locate it. At about that same time; the transponder gave an aural alert 'traffic; 1 mile; same altitude'. When I saw the traffic; we were very close and a couple of hundred feet below it. The other aircraft had little relative motion on the windscreen; so I knew our flight paths would cross very closely. At that moment; I made a split-second decision to exercise Pilot in Command authority; and I deviated from our altitude by initiating a descent. I immediately advised ATC that I was deviating due to traffic; and I was descending to 3;500 feet. The weather was VFR; so I felt like descending was the safest option for the flight. The controller responded that I was below his Minimum Vectoring Altitude and needed to return to 4;300 feet. I told him that we would go back to 4;300 feet when able. I stayed around 3;500 feet until I felt like we were clear of the traffic. The controller asked if I was responding to an RA. I told him; no. I'm not sure if was explained that the aircraft was not equipped with a TCAS. Eventually; we returned to 4;300 feet; got a visual on ZZZ; flew a Visual Approach to the field; and continued the flight without further abnormalities. We were aware of the event the moment it occurred through active monitoring. I think the instructions we received from ATC were the primary factor in this event. I deviated from our assigned altitude to create a safe amount of separation between our aircraft. I should have queried the controller more about the traffic at 4;500 feet as he was having us expedite our descent. That could have given him an opportunity to change his instruction for us. I thought his plan was to get us further below the traffic.


Synopsis: Air taxi First Officer reported being vectored for an approach by TRACON descended below their assigned altitude to avoid VFR traffic which ATC had advised them of but did not issue appropriate instructions to avoid the traffic. ATC advised the pilot they descended below the Minimum Vectoring Altitude.