Communication Difficulties for Unmanned Aerial Teams
During the flood responses, unmanned aerial teams experienced difficulties with communications amongst themselves, incident command, search teams, air assets, and control organizations that included the FAA flight center and TRACON. Early in the event, all cellular and data service was lost due to both physical breakdown of the cellular networks and the overwhelming of the system. This fact made the filing of an eCOA very challenging and required all documentation to be sent through text messaging when service permitted. Once service was re-established, cell phones were a great tool but could not be depended upon due to poor cell coverage in the rural areas. Tactical radios belonging to local authorities were a great resource when available but could not be counted on due to short supply.
Recommendation • At a minimum, all unmanned flight teams must possess a handheld transceiver. It is strongly recommended to use an aviation band, UHF base station. • All air assets must have knowledge of radio frequencies being used in areas of operations. • All members of the unmanned aerial team should have long-range, hands-free, two-way radio systems. • Coordination of air assets should be made by air operations each day; no freelancing. • Access to local authorities’ tactical radio if possible. • Distribute phone list each day during the briefing that includes radio frequencies. • Improve eCOA procedure in case of extenuating circumstances.
Fixed Wing vs. Rotary Wing
When operating an unmanned aircraft, best practices ideally include a three-person flight team comprised of PIC, VO, and PAC. There is a “First Protocol of Unmanned Aircraft Use” which dictates that unmanned aircraft will ALWAYS defer to the manned asset and give way, to the point of disposing of the unmanned aviation system in the most expeditious manner necessary to adhere to the Protocol. The Wimberley aviation unit found fixed-wing unmanned aircraft launching, recovery, and visual observation somewhat difficult due to high tree lines, rocky river bottoms, steep cliffs, vegetative undergrowth, and at times, a densely residential population. However, the range flown and time involved dictated this choice. Typically, the Spectra fixed wing would have to take off from an area offset from the river and rely on its autopilot for way-point navigation. The Spectra has long flight endurance and using its autopilot provides precise imagery over large areas (1.77” or 4.5cm resolution at + or – 10 cm accuracy). While operating at 400 AGL, the aircraft and its autopilot communicate through a ground station (laptop computer). With a flight plan loaded on the ground station the aircraft flies in a “mowing the lawn” grid pattern to obtain overlapping images.
These images can then be processed afterwards, using various software packages, into large ortho-mosaic images for mapping purposes. When searching in larger areas, such as desert or open land, these fixed-wing aircraft images can also be reviewed to search for missing persons and other uses. The Spectra Fixed Wing is responsible for mapping the seven miles of the Blanco River. Lacking vertical takeoff and landing capabilities, a fixed-wing unmanned aircraft requires a certain amount of open space for launch and recovery. Small fixed-wing unmanned aircraft come in many different configurations weighing up to 55 pounds.
Multi-rotor aircraft was favored at times over the fixed wing for its vertical takeoff and landing (VTOL) capability. Early in the flood response, a DJI Inspire quad copter was used to collect imagery for the primary search. The ability to get on scene take high-resolution imagery, and then move to the next location in minimum time made the Inspire a great tool for low altitude information gathering (100’-200’ AGL). Multi-rotor platforms can provide a quick frame of reference and influence decision making that might normally place responders in areas of danger. It should be noted that the DJI Inspire was always under the operator’s control and did not use way point navigation to complete its mission.
Recommendation • Provide Incident Command with both fixed-wing and multirotor capabilities.
• Never allow the failure of one system (single point of failure) to affect the mission. Always have another means to gather information.