Part 107 UAS pilot reported an NMAC with a general aviation aircraft. The UAS pilot took evasive action.

Narrative

At approximately XA:36pm on Day 0; we were operating our Freefly Systems Alta X for a LiDAR and photogrammetry survey mission over a large; unpopulated area for a client. The flight plan was performing north/south pre-planned autonomous legs at 115 meters AGL. I was operating as the RPIC. I identified a manned aircraft at a lower altitude; west of our location and west of our operating area. I was able to confirm this on my ground control station since we use a Uavionix Ping ADS-B in receiver onboard the UAS for situational awareness. I could see the aircraft was operating at 370 some meters AGL and clear of our operating area. A few minutes later; the UAS was on its way back to the landing zone; I had just performed some alignment maneuvers for our sensor; caught movement out of the corner of my eye and coming in from the NW; at or below our UAS's altitude and on a direct bearing to our operations vehicle was a single engine turbo prop aircraft; either a Cessna Grand Caravan or Kodiak; with a sensor of some sort coming from the tail. The aircraft had its landing lights on and passed over us; slightly to the North. I had taken manual control of the UAS and maneuvered it to the south and descended as fast as I could to about 100 feet AGL. We caught the tail number of the aircraft; no owner information found online. Aircraft is operating out of ZZZ1 and seems to be on some type of government mission. I reached out to the FBO to connect with the aircraft's operator since we are still flying UAS in our area this week. I had a current NOTAM filed for the operating area. I am happy to provide additional information and speak on this if necessary. I have a left my contact information with the FBO at ZZZ1 for the crew to contact me; in hopes we can coordinate as their Flight Aware track shows them doing some type of obvious survey work in Location X from ZZZ1 to ZZZ2.