Space weather could have been to blame for the air traffic control surveillance blackouts that hit European air travel on both June 5 and 10 – although authorities admit the exact cause remains a mystery.

A partial loss of aircraft tracking data on air traffic control displays occurred on 10 June at the area control centres (ACC) of Vienna, Bratislava, Karlsruhe, Munich and Prague.

The ACCs concerned, in close coordination with Eurocontrol, the Network Manager (NM), applied ‘appropriate mitigation measures’ which caused some 6,000 minutes of delay to flights.

In parallel, the Network Manager launched an investigation in coordination with the nations concerned, the military, the relevant air navigation service providers (ANSPs) and the European Aviation Safety Agency (EASA).

Eurocontrol said its investigation revealed that similar, but less extensive, radar interference also occurred in some parts of Central Europe on 5 June, adding that it would continue to gather additional input on the incident as regards both its cause and also the response to it.

“[A] possible cause investigated was space weather, although at present this appears unlikely; no space weather event was detected on 5 June and while there was an event on 10 June, this was of a magnitude which was insufficient to cause the interference experienced,” Eurocontrol told Air Traffic Management.

Solar flares are powerful bursts of radiation emitted from the sun, but the radiation cannot pass through the Earth’s atmosphere. However, if the energy emitted from the sun is of sufficient strength and emitted at a particular angle toward Earth, it can significantly disrupt satellite-based communications, including GPS navigation systems.

Technology website Mashable reported that on June 10, the sun emitted a series of powerful solar flares, known as “X-Class” flares, which were observed in brilliant colours by NASA’s Solar Dynamics Observatory. The flares erupted from the left side of the sun, twice on June 10 and once on June 11, according to NASA.

The June 11 flare was classified as an X1.0, whereas the June 10 flares were a bit stronger, at X1.5 and X2.2. According to NASA, “X-Class” flares are the most intense of all solar flares. An X2 flare is twice as intense as an X1, and an X3 is three times as intense as an X1.

A technology experts tells Air Traffic Management: “It is an interesting theory, but these don’t generally affect radars. Widespread communications outages would be much more noticeable.”

Eurocontrol said contingency procedures for addressing such disruptions to air traffic control were applied during the events. “However, due to the potential safety impact of the event, these procedures may need to be reviewed in the light of the experience gained,” it noted.

Technical analysis is ongoing and as the interference could have been caused by some military activity (e.g. jamming) Eurocontrol said it had also contacted NATO although had yet to receive any confirmed information on military activity in the region.

A preliminary report on the event has been prepared and sent to relevant authorities, including EASA, for further consideration and analysis. Eurocontrol added that it was eager to collaborate in further work to prevent a recurrence of these incidents and to coordinate agreed network-wide improvement actions.

Read More: