Flying over war zones and the threat of stray missiles has been keeping airlines on their toes of late, but there is another persistent problem that commercial pilots have been dealing with regularly.
While episodes of airspace closures and costly air route network disruptions are relatively rare, the loss of GPS signals – essential for aerial navigation – is much more frequent.
GPS, or global positioning system, is the satellite-based location network we rely on for everything from Uber rides to finding our lost mobile phone.
Commercial pilots in certain regions frequently lose these navigation signals due to jamming or find them inaccurate because of spoofing. This can lead to critical safety issues, such as automatic “pull up” warnings at high altitudes, desynchronised cockpit clocks, or instrument displays indicating non-existent terrain.
Planes have back-up systems. In fact, modern aviation safety is built on multiple back up safety redundancies. But jamming and spoofing are occurring in greater frequency. A retired captain recounted his experience to this masthead.
“Once, I was flying over Iran en route to London and had one GPS system wander off 20 to 30 miles from what the two other GPS systems were showing.” “This is for a system that’s normally within 1 mile of accuracy.” “The first question was: have I got my GPS playing up?” After the flight, he said, he had the system checked.
GPS signal manipulation, including jamming – the transmission of noise or interference to block GPS signals – and spoofing – sending fake GPS signals – is particularly prevalent on flights through the Middle East and Eastern Europe.
In an A320 flying over Iraq, the Flight Management System (FMS, at left) derives an accurate location, while the GPS (at right) shows a false position. Also at right, the reading of path on aircraft on ground (or true track - TTRK) and ground speed (GS) show zero. Credit: OpsGroup
There have also been occasional reports around Australia from Chinese warships and in the South China Sea, as well.
The manipulation occurs for planes as flights pass adjacent to areas where militaries disrupt or alter GPS signals to ward off attacks, confuse hostile drones and missiles, or harass pilots.
Civilian airlines flying long-haul routes, such as those between Australia and Europe, can be affected. GPS jamming, conducted by military forces, is near constant around Ukraine and parts of Russia.
At any given time, the incidence of spoofing that affects commercial airspace shifts. But to give an example, in July to August 2024, the top airspace regions affected by spoofing were Cyprus, Israel, Egypt, Turkey, Russia and Pakistan, according to GPS Spoofing Workgroup report.
There has been a more than 200 per cent increase in Global Positioning System loss events between 2021 and 2024, according to the International Air Transport Association (IATA).
“With continued geopolitical tensions, it is difficult to see this trend reversing in the near term,” said Nick Careen, IATA’s senior vice president for operations, safety and security.
Spoofing can create some strange effects in the cockpit, like being at 30,000 feet when an alarm comes on telling the pilot to immediately pull up to avoid the ground, or the clocks used by the captain and first officer no longer read the same time. An instrument can falsely indicate a plane is far from its actual location.
Another pilot, who flies through affected regions, said GPS jamming now happens daily.
The aircraft loses the connection to the GPS, and it flies a bit further and regains the signal again. “It’s no big deal if it’s for a limited time while en route.”
GPS spoofing, while less frequent, poses a bigger problem, the pilot said.
“That is much more serious if it goes haywire.” It can change the timing of clocks in the aircraft and in the worst case, it can mess with the instruments reading the position of the plane, he said.
Planes with their GPS spoofed can unexpectedly turn without air traffic control clearance, deviating from their cleared route. This can put them at risk of entering dangerous or military areas, as almost occurred in 2023 on a flight from Europe to Dubai, according to OpsGroup, an organisation of international flight operations professionals.
There’s some history here. Civilian planes didn’t use GPS until after Korean Air Lines flight 007 was shot down by Soviet aircraft in 1983 after it drifted into Russian airspace. The downing of the Boeing 747-230B, amid Cold War tensions, killed 269 people, and prompted the US government to permit the US-built GPS system to be used for civilian aviation.
Experts fear that the abundance of false alarms around GPS can erode a pilot’s awareness, or increase distrust of the data. A recent OpsGroup report identified loss of safe distance between other planes on the air route due to false instruments warnings as one of the safety concern arising from spoofing.
Korean Air Lines: the Boeing 747-230B was shot down by a missile in 1983 after drifting into Soviet airspace. GPS became a standard navigation aid afterwards.Credit: Hansueli Krapf
The GPS Spoofing WorkGroup report also cited instances of surprise altitude climbs by planes initiated by the ground avoidance system in the cockpit.
There is also a longer-term effect, too. “Due to now commonplace encounters of GPS spoofing impacts, there is a gradual, insidious acceptance of increasingly higher risk at [an] organisational level,” a 2024 report concluded.
“Small changes and new behaviours that were slight deviations from the normal course of events gradually become the norm, providing a basis for accepting additional deviance and, typically, higher risk.”
A phenomenon known as “spoofing fatigue” is also emerging: pilots accustomed to frequent spoofing incidents simply stop reporting them.
This can lead to a normalising of risk and reduced situational awareness.
Different readings on instruments in the cockpit can also cause disagreements between pilots and other crew members regarding the best course of action, clouding the decision-making needed for a safe flight.
The pilot interviewed by this masthead said that when they lose GPS en route: “We basically don’t do anything unless a secondary navigation system warns that the plane’s route is becoming less precise.”
Planes can activate a back-up system called Distance Measuring Equipment, which had been the standard before GPS became commonplace.
The pilot said he has never been lost because of jamming or spoofing; however he has been “slightly off track” and had to ask air traffic control for help. “That has been because of prolonged GPS loss.”
In the pilot’s region and with his company, the GPS interference phenomenon is well understood.
“So we have a spoofing guide/checklist so we can prevent some follow-on effects”
There can be complex situations but he said, “We always have back-up plans.”
While pilots adapt, lack of GPS can have serious consequences.
On Christmas Day last year, Azerbaijan Airlines Flight 8243 left Baku for Grozy in the Russian republic of Chechnya when it lost its GPS signal. Russian military forces in Grozny, on guard for Ukrainian drone attacks, had been GPS jamming the area.
Flight 8243 tried to approach Grozny twice, said FrontierSI’s technical lead Eldar Rubinov. The plane lost GPS on approach to Grozny and asked air traffic controllers for guidance to the runway, he said.
“They tried the approach twice, but both times when they reached the decision-making height (or minimum), they were still above the clouds and couldn’t establish a visual contact with the runway.”
“After the second attempt, they indicated to the air traffic control, that they cannot land and they are returning to Baku, and that’s when they got shot by an anti-aircraft missile.”
The pilots mistook the sound of the missile hit for birdstrike. The plane crashed, killing 38 people while 29 survived with injuries.
“If they had GPS, their minimum would be much lower, so they could’ve descended below the clouds without any issues,” said Rubinov, who audited the plane’s blackbox recording.
The lack of GPS was a contributing factor to the crash, Rubinov said.
In response to the growing problem of GPS interference, IATA along with the European Union Aviation Safety Agency last month proposed several solutions: standardising radio calls for GPS interference, establishing monitoring and warning practices, and facilitating information sharing.
The groups also advocate for restrictions on jamming devices, though the effectiveness of such restrictions is questionable in regions like Russia’s Kaliningrad, a major jamming hotspot, or in Israel.
Another potential solution for commercial flights is a controlled reception pattern antenna (CRPA). This technology can detect and completely block interfering signals from a specific direction, making it almost unjammable.
One retired captain told this masthead: “There are redundant navigation systems, but the GPS is ‘the’ method of navigation around the world, so if they (jammers and spoofers) turned that off, it would be haywire.”
The Business Briefing newsletter delivers major stories, exclusive coverage and expert opinion. Sign up to get it every weekday morning.