Estonian Air Navigation Services expands the availability of alternative navigation option

Posted on 16. May 2024

Soon, the distance measuring equipment solution (DME) that Estonian Air Navigation Services has implemented, will offer an alternative navigation option in case of GPS interference also in lower airspace. This fulfills an important precondition for the restoration of Finnair's Helsinki-Tartu scheduled flights in Tartu airport.

"We have received an official confirmation that the signal from ground-based Distance Measuring Equipment, or DME, provides sufficient coverage in the lower part of the airspace to use it as an alternative navigation tool for the pilots," said Ivar Värk, CEO of Estonian Air Navigation Services. "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."

DMEs are devices on the ground, from which the signal is sent to the aircraft's onboard display allowing to pinpoint its location. DMEs have been used previously in Estonia, and last year the Estonian Air Navigation Services increased their number across Estonia to have better coverage. DMEs have been an alternative means of navigation for traffic exceeding 3 km since March, and now their use has been extended to lower airspace as well.

"During validation we found that the signal sent from the DMEs works very well at an altitude range where the additional coverage was needed, so that flights can reach, in Tartu case, from controlled airspace to the final of instrument landing system or ILS. Now we need to add this solution to the procedures and then the pilots can start using it," added Värk.

The possibility of using DMEs fulfils an important prerequisite to resume Finnair's flights between Helsinki and Tartu. 

"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 Üllar Salumäe, Director of Aviation Division of Estonian Transport Administration. "We have been dealing with a new problem arising from geopolitical tensions and we have reacted and found a solution for it."

Any pilots whose onboard equipment and flight procedures support it, can use DMEs as an additional navigation system.

Tallinn remote tower centre has been serving Tartu Airport flights as usual after the suspension of Finnair flights and will continue to do so. Aside from the two Finnair cases, there have been no flights returned or scheduled flights cancelled due to GPS disturbances in Tartu or elsewhere in Estonian airspace.In cases of GPS interference, pilots have used alternative navigation tools or support provided by flight information service officers, if it accords their flight procedures. In the controlled airspace surrounding Tallinn Airport and Estonia at an altitude of 3 km higher, air traffic controllers monitor and direct flights.

Estonian Air Navigation Services is a state-owned enterprise in Estonia that provides safe and digital air traffic services for both unmanned and manned flights, develops aviation, and manages Estonian airspace.