Date: 202106
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Weather elements / visibility: Icing; Cloudy; Thunderstorm; 10
Light: Daylight
Aircraft: Large UAS; Fixed Wing
Operator: Military
Operating under: Public Aircraft Operations (UAS)
Flight plan: IFR
Mission: Training
Flight phase: Cruise
Airspace: Class A ZZZ
Reporter organization: Military
Reporter function: Remote PIC (UAS)
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown; Confusion; Situational Awareness
Anomaly: Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Person UAS Crew
When detected: In-flight
Result: Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Contributing factors: Human Factors; Procedure; Weather
Primary problem: Ambiguous

Narrative: I was doing student training in the vicinity of ZZZ at FL270. The clouds were building in the area and climbing up through our flight level in a relatively short amount of time. The ATCAA (ATC-assigned Airspace) was just south of our position and went hot while we in the area. Center restricted our working airspace clearance to remain north of the ZZZ airport and we accepted. The weather and high clouds were just a few miles north of ZZZ and started to severely limit our maneuvering airspace and we were getting boxed in between staying out of the weather and complying with the airspace clearance. During crew swap; I briefed the incoming pilot about the weather/high clouds and the requirements to stay north of the ATCAA. I also advised him that it was probably time to depart the area as it was becoming unworkable due to the building weather. I showed him that my student was currently on a heading that was pointing in the direction of the weather (approximately 040 heading) and he would need to turn south before the aircraft entered the cloud and possibly picked up ice. I did not specify; but I intended for the turn to be made to the right where there was still clear air. It also should have been a manual bank heading to steepen the bank angle enough to avoid flying into the ATCAA. I assumed he understood what I wanted him to do; but I did not get any communication from him that he was confused about my instructions. He said he's got it and then proceeded with the crew swap and dismissed my student from the flight controls. After the incoming pilot sat down; he commanded a left turn with the autopilot (14 degrees of bank) and turned right into the clouds. The aircraft began picking up icing and he [contacted] Center to avoid flying into more weather/icing. Upon my student exiting the ground control station; I began talk to him about his handover briefing and I did not notice the aircraft turning left until it was already in the weather. I debriefed with the incoming pilot later and he told me at the time of the crew swap; he had no idea where the clear air was and therefore was forced to exit the area immediately which resulted in him eventually [contacting] Center in order to get clear of the weather.




Synopsis: Multi person UAS flight crew was conducting a crew swap while UAS was flying near weather and building clouds. After crew swap the UAS was flown inadvertently into icing conditions and was able to exit.