Extended-range monitoring and surveillance of facilities and infrastructure--such as oil, water, and gas pipelines and power lines--employs autonomous vertical take-off and landing (VTOL) capable, small unmanned aerial system (sUAS) aircraft and docking platforms for accommodating the sUAS aircraft. Monitoring and surveillance of facilities using one or more embodiments may be performed continually by the sUAS flying autonomously along a pre-programmed flight path. The sUAS aircraft may have an integrated gas collector and analyzer unit, and capability for downloading collected data and analyzer information from the sUAS aircraft to the docking platforms. The gas collector and analyzer unit may provide remote sensing and in-situ investigation of leaks and other environmental concerns as part of a "standoff" (e.g., remote from operators of the system or the facilities) survey that can keep field operators out of harm's way and monitor health of the environment.