The Impact of GPS Signal Interference on Aircraft Navigation in the Contiguous USA

Global Positioning System (GPS) interference events can have a significant impact on flight operations. During these events, the Federal Aviation Administration (FAA) must reconfigure the National Airspace System (NAS) to use the available navigation capabilities, often at the expense of capacity and efficiency. Recent well-publicized events, such as the interference with GPS-based navigation in the Dallas Fort Worth (DFW) area on October 18, 2022, have caused noteworthy disruptions. The FAA has tasked The MITRE Corporation’s Center for Advanced Aviation System Development (MITRE CAASD) to develop a web-based prototype Navigation Operations and Planning Agility Suite (NOPAS) that can be used to identify GPS loss of navigational service events in terms of 4D geospatial regions, for the current operational day, or for previous historical dates. The airspace above the entire United States (US) must be included in this capability. This prototype must also incorporate the ability to determine whether alternative aircraft navigation based on ground-based navigation aids can be performed at these 4D geospatial regions with an identified GPS loss of navigation service. This paper describes the development of a prototype NOPAS to display aircraft navigation capability across the U.S., based on the reporting of Navigation Integrity Category (NIC) from aircraft Automatic Dependent Surveillance – Broadcast (ADS-B) messages as an indicator of likely navigation performance. The prototype NOPAS combines the detection of loss of GPS navigation services for aircraft in the U.S. along with the availability of alternative navigation services using the network of ground-based navigation aids (i.e., Distance Measuring Equipment (DME) and Very High Frequency Omnidirectional Range (VOR)). NOPAS ingests and processes all aircraft-generated ADS-B messages collected by the FAA from a dedicated ground network and fills in any gaps in reported airborne position from these messages with FAA radar surveillance-based aircraft location data. This data is then processed into a hexagonal index and displayed incorporating the additional dimensions of altitude bands and time-period. The user can also display impact metrics based on this data in aggregate form. These statistics can be used, for example, to identify specific quarter-hour periods where the impact is greatest for a particular day. The NOPAS prototype also includes similar capabilities using crowdsourced public ADS-B data. NOPAS is the first prototype application developed for the US government that combines the capability to detect and depict GPS loss of service events geospatially, combined with the corresponding availability of alternative ground-based navigation services, in a single web-based capability for the entire US.