Precise position service to satisfy ADS-B out mandate

The Federal Aviation Administration (FAA) has mandated equipage requirements and performance standards for Automatic Dependent Surveillance-Broadcast (ADS-B) Out avionics on aircraft operating in Classes A, B and C airspace, as well as certain other specified classes of airspace within the U.S National Airspace (NAS) by 1 January 2020. ADS-B Out periodically broadcasts information about an aircraft, such as current position, through an onboard transmitter. The FAA's final rule states that, “any ADS-B position source that meets the specified performance standards is acceptable and complies with the requirements in the final rule [1].” The position source information broadcast for ADS-B is not required to be from the sensor that is being used for navigation. It is currently required for United States Air Force (USAF) aircraft to use Precise Positioning System (PPS) Global Positioning System (GPS) for combat, combat support and combat service support operation. Standard Positioning System (SPS) is currently accepted in civil airspace worldwide for navigation; the use of PPS for navigation is accepted in the United States but not currently accepted in all countries for civil use. To satisfy both requirements, many USAF aircraft are forced to equip with both types of GPS. Providing the transponder with PPS GPS information to satisfy the current ADS-B mandate could also enable future growth to an encrypted squitter like ADS-B function that could provide aircraft location in the area of responsibility (AOR). This paper outlines the advantages and disadvantages of using a PPS sensor to satisfy the ADS-B mandate. This paper will also discuss how the use of one type of position source to satisfy the mandate could potentially benefit the USAF, specifically in the area of integration.