Global Navigation Satellite System (GNSS) is an all-encompassing term that refers to any satellite-based position, navigation and timing (PNT) system that provides information to receivers such as portable GPS units and aircraft-mounted receivers. The US GPS is one such GNSS, and there are others such as Europe's Galileo, Russia's Global Navigation Satellite System (GLONASS), China's BeiDou, and regional systems in Japan and India.
Reports of false signals compromising aircraft navigation systems have surged in the Black Sea region in recent years. The security intelligence organization OpsGroup first reported these incidents, noting that false or jammed Global Navigation Satellite System (GNSS) signals have affected US Global Positioning System (GPS) civilian signals, causing aircraft navigation systems to display missing or inaccurate position information. Recently, an OpsGroup member reported encountering GPS spoofing after departing from Israel's Ben Gurion International Airport (LLBG) on January 29. "This continued until the FIR boundary. ATC was notified and provided us navigation instead," the pilot said.
GPS interference caused by GPS signal jammers can drown out relatively weak GNSS signals. Disrupting GNSS is illegal in the United States and many other countries. Jamming and spoofing are two different threats. Jamming is the sending of strong radio waves to suppress or mask satellite signals, making it impossible for receivers to receive and process satellite data normally. Spoofing is more complex and is the sending of fake signals to trick receivers into calculating the wrong position, which can cause the aircraft to deviate from the intended route. Many modern avionics rely on GNSS, and jamming and spoofing can cause problems beyond navigation, such as autopilot shutdown.
On December 3, 2022, a pilot posted the following on the Phenom Pilot Forum (for pilots flying Embraer Phenom 100 and 300 jets): "On December 1, I took off from Lahore, Pakistan (OPLA). At about 1,500 feet, I encountered GPS jamming (or possibly spoofing). The GPS malfunction caused the AHRS (attitude and heading reference system) to fail, and on top of that, the HSI (horizontal situation indicator) compass began to spin rapidly and became unusable, and the autopilot failed. The AHRS did not recover. Of course, we did not fly below 200 knots and wings level for 5 minutes. We were more concerned about returning to the airport. The handheld GPS unit was also jammed in this situation. We also immediately received a TAWS (terrain warning and alert system) warning that it needed to be silenced. I cannot emphasize how confusing and unsettling this situation was. Takeoff, GPS malfunction, TAWS collision alert, autopilot disconnected, spinning HSI compass, all at the same time."
According to OpsGroup, GPS Reports of spoofing continue to increase and expand. The group said it received nearly 50 reports of false signals affecting aircraft operators last year. The group first raised the alarm about spoofing in September last year, citing a dozen reports of aircraft being hit by false signals while flying over Iraq near the Iranian border. In many cases, this resulted in a complete loss of navigation capabilities.
In late October, reports of actions came in from the eastern Mediterranean, Egypt, and Amman, Jordan. In these cases, aircraft were shown with false positions stationary over Ben Gurion International Airport (LLBG), even though they were as far as 212 nautical miles from the area. The most recent incident involved a flight that took off from LLBG and was directed to Lebanon by a spoofed signal.
According to OpsGroup, on December 12, a member reported encountering spoofing near OPLA while flying a Bombardier Global 6500. By running one FMS (Flight Management System) with GPS input turned on and another FMS with GPS turned off, the crew was able to observe a false GPS position showing the aircraft as being 75 nautical miles northeast of its actual position. ATC told the crew they were actually on the correct route.
On December 26, cargo airline UPS sent a "Company NOTAM" to pilots warning of jamming and spoofing in Azerbaijan airspace and over the Black Sea, Red Sea and eastern Mediterranean. "UPS has contacted Boeing about this matter and Boeing, UPS, EASA and FAA are actively monitoring this matter." The notice warned that "false EGPWS alerts may occur at any time during or after GPS spoofing due to contamination of the GPS altitude of the Enhanced Ground Proximity Warning System (EGPWS). Disabling GPS updates in the FMC will not protect the EGPWS from spoofing." UPS asked pilots to photograph the indication and submit an incident report. "Boeing will issue an updated Flight Operations Technical Bulletin in the near future to address the issue for specific models," the UPS notice stated.
The dangers of GNSS jamming and spoofing are increasing, affecting aviation operations and navigation activities around the world. This phenomenon not only poses a serious challenge to aviation safety, but also reminds the international community to strengthen its attention and protection of GNSS safety.