LFV: Full capacity in Swedish airspace after 90 minutes radar loss

The investigation, made by LFV, after the radar disruptions that affected parts of Sweden’s air traffic on 4 November 2015, shows that the disruptions were due to radio emissions linked to a solar flare. This is the conclusion from the investigation conducted by LFV after the event.

On Wednesday 4 November 2015, at around 16:00 hours, air traffic control centres in Stockholm and Malmö noticed the first indication that LFV radar stations were not relaying the correct data to air traffic control. The cause was rapidly identified and measures taken.
“When the disturbance occurred, those of our air traffic controllers who were unable to use the information on their radar screens, changed over to a different way of managing the aircraft,” says Ulf Thibblin, Technical Director, LFV.

To LFV, safety is our main priority. If safety for different reasons, bad weather or technical disruptions, could not be guaranteed, the number of air traffic is being reduced.
In recent days, there has been discussions that the interference were not related to space weather, but that it instead was due to a cyber attack against Sweden.
“Early on in our investigation we had this as one of other hypothesis.  But there was nothing in our radardata- or Internet traffic logs to support or confirm a possible cyber attack. Also, we had the relationship in time with space weather, plus there were a few more technical reasons which excluded a cyber attack, says Ulf Thibblin.”

After affected radar stations had been restarted, LFV’s air traffic controllers received correct radar presentation 45 minutes after the disruption had begun and after an additional 45 minutes there was full capacity in the airspace.

Over the past 17 years, LFV radar stations have only been affected by similar problems twice, in 1999 and 2003. The disturbances both then and now took place at sunset, when the angle of the sun goes – for the most part – directly into the radar stations.
According to experts, it is possible to predict a solar flare but not its consequences, for example radio emissions. As the disturbance is carried from the sun to the earth at the speed of light, it is also impossible to receive prior warning of an established outburst.

LFV’s radar stations around Sweden are continually upgraded and will remain in use. However now they will be supplemented with a new type of radar known as Wide Area Multilateration, WAM, which means the robustness will increase significantly.