Part 107 UAS pilot reported the UAS crew was operating two UAS near a Class D Airport with authorization. A manned fixed wing aircraft made an approach to a different runway and had a near miss with one of the UAS. There was no collision and all aircraft landed safely.

Narrative

Operation Overview: Crew consisted of 4 people and 2 UAS. There were 2 pilots; 1 gimbal operator; and 1 support person. Each pilot was in command of a single UAS. One of the pilots and support person were monitoring the ATC radio communications. The operation consisted of manual; synchronized fight of both UAS. During each flight both UAS traversed from ground level to max flight altitude in a fixed location repeatedly for approximately 15 minutes. The two UAS were separated by approximately 300 meters facing each other. The UAS Pilots were in constant communication with each other during the flights.Prior to deployment we applied for and were granted a COA for operating inside Class-D airspace. We followed all special provisions outlined in the COA. Including contacting the Tower prior to starting UAS operations and monitoring the Tower frequency prior-to and during UAS flights. Prior to takeoff of the flight in which the incident occurred we confirmed systems and personnel ready between both pilots and the gimbal operator. In the first 10-20 meters after takeoff both pilots were watching speed readings on the drone remote screens to match ascent rates of 3 meters per second. Once the ascent rate was achieved Pilot-1 looked up to get eyes on UAS-1 and immediately noticed a low flying manned aircraft dangerously close; with a heading directly in line with UAS-1. Pilot-1's immediate action was to start descending; but they realized the manned aircraft was also descending and already at a similar altitude to UAS-1. Pilot-1 quickly changed to a full rate ascent to get above the descending trajectory of the manned aircraft. The manned aircraft had not been seen or heard by any of the crew until it was approximately 1;500 ft east north-east of UAS-1's location; in line with Runway XX. We estimate that manned aircraft was 60 ft directly below UAS-1 at time of the near miss.After the incident the team decided that having the ATC communication radio attached to Pilot-2 was insufficient for monitoring ATC communications since Pilot-2 was communicating with Pilot-1 and there was additional environmental noise from the processing facility. The team decided a better course of action was to have the support person wear the radio and focus primarily on ATC communications while operating as a visual observer. The team also discussed better ways of avoiding incoming manned aircraft. Later in the day; after we had implemented the above changes to our operation; another aircraft landed on Runway XX. The support person heard ATC communication and was able to give both UAS Pilots a 10 mile out warning giving them plenty of time to land both UAS before the manned aircraft arrived.Contributing factors: Noise from nearby machinery in the processing facility and road traffic. UAS Pilot to UAS Pilot communication distracted from ATC Radio communication monitoring. Team unfamiliarity with Runway XX approach path with respect to our operating location's visual landmarks.Corrective Action: It has been decided that in all high air-traffic scenarios the team must have at least one member whose only responsibilities are monitoring air-traffic radio frequencies and visually checking for intruding aircraft. Thorough preparation must be done before the start of operations; and after any changes to the expected operations. This preparation shall at least include identifying air-traffic patterns relative to our operating areas; this may include specifying landmarks to reference. As well as; what to do if an aircraft enters our operating area; this shall include both pilot actions and expected communication between the pilots and crew.