Finnair restarts Tartu flights after alternative to GPS approach systems found

Finnair is to resume flights between Tartu and Helsinki next month, after steps were taken to mitigate hazards its aircraft had faced on approach to the airport at Estonia's second city, due to Global Positioning System (GPS) jamming.
Üllar Salumäe, director of the Aviation Division of the Estonian Transport Administration, said: "All parties have cooperated well together in order to make an additional navigation option possible and restore Finnair flights."
"That allowed us to speed up the process as much as possible without compromising on safety," said. "We have been dealing with a new problem arising from geopolitical tensions and we have reacted and found a solution for it."
Finnair suspended flights to Tartu for a month to allow the introduction of an approach solution that does not require a GPS signal.
This solution, ground-based Distance Measuring Equipment (DME), allows any flight crews whose onboard equipment and flight procedures support it to use it as an additional navigation system.
Ivar Värk, CEO of state agency Estonian Air Navigation Services (EANS) said: "We have received an official confirmation that the signal from provides sufficient coverage in the lower part of the airspace to use it as an alternative navigation tool for the pilots."
"This means that we have found a solution that enables us, as part of the current flight information service, to continue serving also these flights for which GPS or another conventional navigation solution is a necessary prerequisite according to the airline's procedures," Värk went on.
The approach methods previously used at Tartu airport were based on GPS signals, and were susceptible to intentional interference in the area, to the extent that aircraft were sometimes effectively from approaching and landing at the airport.
As a result, Finnair suspended flights between Helsinki and Tartu from April 29 to May 31 inclusive. Normal service resumes on June 2.
Jari Paajanen, Vice President, Operations Control at Finnair, said: "EANS has done an excellent job in implementing the alternative method. I want to thank all our partners in Estonia for resolving this matter so swiftly."
DME is based on radio signals sent from ground stations, a practice already long in use in aviation and still used at some airports as an alternative to GPS-based approach methods.
They had already been in use as an alternative navigational means for air traffic at altitudes of 3,000 meters or higher, and simply have been extended in scope at Tartu to lower altitudes.
The EANS-implemented DME starts operating from May 23.
Finnair flies to Tartu twice a day, six days per week, operated by Finnair's partner Norra and using ATR planes.
GPS interference has increased clearly since 2022, but generally has not impacted the safe operation of flights, Finnair says.
The carrier's aircraft systems detect GPS interference so the switch to alternative aids can be deployed, while Finnair and Norra pilots are also well aware of GPS interference and know how to prepare for it.
Usually, GPS interference does not affect flight routes or flight safety, due to flight crew awareness and the existence of alternatives like DME.
In the week starting April 22, two Finnair flights had to divert back to Helsinki after GPS interference prevented them from landing at Tartu Airport.
Minister of Foreign Affairs Margus Tsahkna (Eesti 200) said at the time that the jamming was a deliberate hybrid attack on the part of Russia.
Aside from the two Finnair cases, there have been no flights returned or scheduled flights canceled due to GPS disturbances in Tartu, or elsewhere in Estonian airspace.
Some sources say a GPS jammer affecting the southeastern Baltic Sea region is located in Kaliningrad, potentially along with another located in St. Petersburg to the north.
The Baltic Jammer is in Kaliningrad.
— Markus Jonsson (@auonsson) April 6, 2024
5th proof, 3rd method.
This time with numbers on likelyhood. We just need a statistician to tell us how sure we are. Surely over 9000.@PajalaJussi computed how many radio horizons of first jammed plane intersect. Here, heatmapped. pic.twitter.com/9zMYvwtxQP
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Editor: Andrew Whyte