Although Ligado Networks has pledged to ensure its proposed ground-based cellular operations will fully protect certified aviation GPS receivers, it doesn’t have the support of everyone. The Helicopter Association International (HAI) and 10 other aviation-related associations are concerned that its proposed network will pose interference issues for aviation.
The aviation groups say that thorough assessment and testing are essential to address their issues and that empirical data, obtained from credible industry-accepted standards, must be obtained.
“From the perspective of operators that conduct a variety of missions in the low altitude environment, including unmanned operations, often in close proximity to flight obstructions, a loss of navigational accuracy/reliability would produce distractions for operators, unnecessarily increase crew workloads, and could have adverse impacts on the ability to safely navigate,” HAI and others said in a June 15 letter to the FAA. “Additionally, within areas of high density tower deployment, operators could potentially experience repeated loss of GPS.”
Other signatories to the letter are the Air Line Pilots Association, Airborne Public Safety Association, Aircraft Owners and Pilots Association, Airlines for America, Association of Air Medical Services, Helicopter Safety Advisory Conference, National Agricultural Aviation Association, National Business Aviation Association, National EMS Pilots Association and the Professional Helicopter Pilots Association.
Ligado has been trying to get a plan approved for years and in May, it filed an amendment to its pending license modification with the FCC that protects certified aviation GPS by reducing the power level at which certain of its downlink connections will operate.
The concerns on the part of the helicopter community are notable because the company used helicopter operations as part of a worst-case scenario in which to plan. Before its May filing, Ligado participated in consultations with the FAA and Department of Transportation, where they set out to determine the safest power level for certified aviation GPS devices. In doing so, they looked at the worst-case scenario in order to get to the best outcome for GPS, which meant providing the maximum protection for helicopters’ GPS to operate safely; they’re allowed to get closer to things like wireless towers than fixed wing aircraft.
“Since our initial filing more than 2 ½ years ago, Ligado has consistently said it would defer to the expertise of the federal government to protect aviation safety,” a Ligado spokesperson told FierceWirelessTech in a statement Friday. “After extensive consultations with all stakeholders, both the FAA and the DOT have concluded that a power level of 9.8 dBW will protect certified aviation devices, even under the most demanding conditions. We respect the judgment of the federal government’s aviation safety experts, which is why we amended our application to adopt their recommended power level.”
Other evidence in the record, including test results from the National Advanced Spectrum and Communications Test Network study and from the Roberson and Associates testing as well as coexistence agreements with the GPS device manufacturers, established that other GPS devices can coexist with Ligado’s proposed operations, according to the company.
The company previously has said it plans to invest up to $800 million in its satellite and terrestrial network capabilities as it prepares to serve industrial IoT and emerging 5G markets in critical infrastructure areas like rail, trucking, utilities, public safety and oil and gas.
The HAI also has corresponded with the FCC recently on another spectrum matter. HAI told the FCC that any decision to repurpose the 3.7-4.2 GHz band must be fully supported by appropriate analyses and testing to ensure a complete understanding of any interference or adverse impacts to aviation systems.
The radio altimeter is a critical piece of equipment and it operates within the adjacent Aeronautical Radio Navigation Service allocation of 4.2-4.4 GHz, providing safety-of-flight information to crews.
“HAI recognizes the benefits that come with an effective utilization of the radio spectrum,” the association said in a May 31 filing (PDF). “However, in consideration of the potential adverse impacts to safety-of-flight systems, HAI strongly recommends that the Commission partner closely with the FAA, NTSB and industry to gain a complete understanding of the potential impacts to radio altimeter operations that could result from commercial wireless operations in the 3.7-4.2 GHz band.”