Landing airplane during sunset.

GPS jamming in aviation underscores industry need for Iridium STL


Under the specter of increased jamming and spoofing of global navigation satellite systems, including signal interference in the geopolitical hotspots of Northern Europe and the Middle East, Iridium is putting the wheels in motion to bring to aviation its new positioning, navigation and timing service called Satellite Time and Location (STL). This is the technology it acquired when it bought Satelles.

On the heels of Finnair’s announcement that it has suspended daily flights to Tartu, Estonia due to GPS signal interference that prevented aircraft from approaching and landing — forcing two flights to divert back to Helsinki — Runway Girl Network sought an update from Iridium on its work to bring STL to the sector.

“This sort of event is happening more and more around the world and demonstrates the exact opportunity Iridium is addressing with the acquisition of Satelles. While aviation wasn’t our first priority with Satellite Time and Location (STL), it’s increasingly becoming an important area of concern to the global aviation community,” Iridium CEO Matt Desch told RGN.

“We expect to work with avionics partners to bring solutions to this market, but as with all things in the aviation domain, it may take them time to get their solutions approved and certified. Our technology is ready though and well tested in other domains.”

Positioning, Navigation and Timing or PNT is an inside baseball term that essentially means delivering precise time synchronization to all kinds of digital things that need it or need to get it more efficiently, as well as delivering trusted information about a device’s location that can’t easily be jammed or spoofed for government, civil and commercial applications. It’s applicable to critical infrastructure, data centers, financial markets, the wireless industry, maritime, IoT and indeed aviation, according to Iridium.

“These are all areas that are dependent on timing and location data from GNSS [global navigation satellite systems] and need an alternate source as a backup or that can reach indoors more effectively,” Desch explained to journalists during a virtual briefing in early March when the firm first announced its intention to acquire Satelles, of which it had been a long-time investor.

The deal closed one month later, and the service was renamed Iridium Satellite Time and Location (STL). It is billed as being capable of addressing vulnerabilities and limitations faced by GPS and GNSS with a time and location capability that secures PNT-dependent applications against disruption and manipulation.

“We saw the value early on and the need for an alternate or backup to GPS as it was being used more and more in all aspects of our digital lives and economy but was susceptible to manipulation through jamming or spoofing. [GPS] also only works outdoors and was needed indoors as well and our network was particularly well suited to deliver the service to our customers globally,” said Desch.

Iridium operates a unique cross-linked global network of L-band Low Earth Orbit (LEO) satellites. And as such, STL “is an incredibly efficient use of our network. It’s a broadcast service that has the capacity to serve … billions of devices with little impact on our network capacity,” said Desch.

“That’s why we wanted to really move from where we were in the wholesale side of selling signal capacity to the retail side of providing solutions to the market either directly or through our 500 other partners. It’s ready to be more widely deployed now, and we plan to focus more on reducing the size and the cost of the technology to make STL service even more easy and inexpensive to integrate and deploy.”

Though aviation wasn’t, as Desch noted, the primary reason for acquiring Satelles, it is proving to be a key industry that will be served in various capacities. To wit, Iridium last month announced a new five-year commercial contract with L3Harris Technologies to provide the STL service to more than three dozen L3Harris-operated communications network backbone nodes and a similar number of Federal Aviation Administration (FAA) facilities throughout the United States.

“L3Harris owns and operates a private nationwide network for the FAA, providing voice, data, and video communications for the National Airspace System operations and mission support functions. Timing synchronization is essential within the L3Harris communications network, especially since it supports several critical infrastructure applications. The Iridium STL service is a vital component of the overall network timing architecture that removes dependencies on GPS as a primary timing source,” McLean, Virginia-based Iridium said at the time.

But from a flight ops standpoint, the value of STL is becoming increasingly apparent given the latest revelation from Finnair about jamming in Baltic countries, and indeed the rise of such events elsewhere including the Middle East.


The problem is so acute that the European Union Aviation Safety Agency (EASA) two years ago issued a warning to aviation authorities, air navigation service providers and aircraft operators that jamming of global navigation satellite systems is being observed by aircraft around Russia and Ukraine, and recommended adoption of mitigation measures.

In January 2024, EASA and the International Air Transport Association (IATA), following a joint GNSS spoofing and jamming workshop, announced their conclusions about the scope of the problem, and the measures agreed to make PNT services provided by GNSS more resilient.

“GNSS systems offer tremendous advantages to aviation in increasing the safety of operations in a busy shared airspace,” said EASA Acting Executive Director Luc Tytgat. “But we have seen a sharp rise in attacks on these systems, which poses a safety risk. EASA is tackling the risk specific to these new technologies. We immediately need to ensure that pilots and crews can identify the risks and know how to react and land safely. In the medium term, we will need to adapt the certification requirements of the navigation and landing systems. For the longer term, we need to ensure we are involved in the design of future satellite navigation systems. Countering this risk is a priority for the Agency.”

Desch reckons that aviation still doesn’t quite appreciate the risk, however.

Aero work ahead

Asked during the press briefing about Iridium’s migration strategy as it relates to older devices that rely on satellite such as Garmin’s panel solutions in general aviation, Desch said in relation to backwards compatibility: “I mean that obviously wouldn’t work in existing radios — it’s not something that you can just sort of turn on magically. It requires some additional hardware, but we’re making our strategies to make that really, really low cost and almost insignificant and the extent that might not even need a new antenna because you might be able to get into the panel directly from outside, you know, using our system.”

Commercial aviation applications would naturally require appropriate avionics solutions. Effectively, STL would be “kind of a constant check on whether or not you’re being tampered with or spoofed, which could be critical, you know, particularly in commercial applications for aviation”, explained Desch.

Broadly, Iridium sees the overall market for time and location capabilities as becoming a multi-billion dollar market over the coming years .

“[W]e plan to be the biggest player and we already have the best solution available that is mature, ready, and well ahead of other solutions,” said the Iridium CEO. “It’s also a solution that couldn’t be easily replicated by other satellite operators unless they had a cross-linked L-band network in Low Earth Orbit and access to all the patents and technology that Satelles has created and deployed over the years.”

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