## 4 Discussion
This approach was adopted because the prototype UTM was seen as an added layer of networking, which required specialized training to navigate, and could further encumber the UAS flight crews, possibly creating an unsafe operating environment. However, during the TCL2 flight campaign, guided by suggestions from the NASA human factors team, the team did begin to experiment with integrating the UTM functionality into the crew stations. A second laptop at each UAS ground station allowed crews to monitor audio warnings regarding their own or nearby UAS. Eventually, many of the teams began to check the visual display as conditions were permitted to get an increased sense of situational awareness. By the end of the campaign, crews began to proactively examine the potential interactions between their and other UAS flight boundaries prior to the mission. TCL3 lessons learned/recommendations: For TCL3, UAF put forth an aggressive set of scenarios involving the new technologies of radar, optical camera, and ADS-B-based SAA/DAA. The campaign provided on opportunity for UAF and its partners to gain valuable experience regarding the development of advanced technical capabilities and USS features and provided important insights. * Pace of the rapid development program: The overall pace of the UTM development program was challenging at times due to the rapid changes being made to the prototype UTM/USS software at this stage in the program. This was evidenced by a late lockdown of the developmental USS interface and required functions that sometimes slowed flight test efforts. In addition, late delineation of the Data Management Plan (DMP) requirements and formats had a negative impact on manpower and flight activities. DMP requirements for the early system were extensive, requiring much analysis of systems and training of both engineering and flight crew personnel. * UTM/USS communications (tactical communications): While overall beneficial to the test campaign, UAF's move of the flight operations from PFFR to the UAF campus area did come with new challenges. The UTM/USS communications were stressed by persistent issues with connections to the internet accessed via a 4G LTE and UAF wireless network. These issues further complicated the establishment of reliable communications supporting the UTM/USS system. * UTM/USS communications (networking): The prototype system was complex, requiring an exacting sequence of events to be performed in a specific order to establish the communications links among UAS, USS, and UTM. This process was further complicated for flights involving additional assets such as the ground radar. The complexity of the procedure required 1-1.5 h to set the system up before each day of flight. In addition, the data link was somewhat temperamental with respect to data timing and signal levels, often requiring the system to be reset and/or for missions to be reflown. The complexity of these issues required UAF to dedicate a full-time engineer solely to the task of UTM/USS communications. Beyond the learning opportunities and problem-solving techniques mentioned above, UAF benefitted significantly from participation in the UTM TCL3 campaign in several other areas. * USS integration into GCS: NASA demonstrated much concern for developing the UTM system in a fashion that sought to minimize impacts on the operational community. In support of this, in TCL3 UAF attempted to integrate the UTM/USS functions more directly into the flight crews' operations by providing USS Web Client machines either colocated or in close proximity to flight crews. UAF/Simulyze was successful in integrating much of this information directly into the Mission Planner GCS. This integration proved especially valuable in providing the flight crews with situational awareness of their UAS in relation to airspace volumes and nearby UAS/aircraft. * Automated ADS-B SAA/DAA; UAF successfully demonstrated the initial capability of the automated SAA/DAA function utilizing the Pixhawk/ADS-B interface.