March 8, 2013

Experts say solar activity could reach its cyclical peak in the second half of 2013, causing a possible increase in space-weather-related events. Solar activity like geomagnetic or solar radiation storms can affect the performance of certain aerial navigation systems, including ground stations and satellites.

“There are several reasons why people in business aviation should pay attention to this,” said Emilien Robert, an expert on space weather with Eurocontrol, the European organization for the safety of air navigation. “First, there are more space-weather events during periods of high solar activity. Aviation, like the rest of society, has become increasingly dependent on satellite technology that could be disrupted by space-weather events.”

“While we want to avoid over reacting, this subject has become more urgent as we enter the peak of the cycle,” said Zarko Sivcev, a crisis management expert at Eurocontrol.

Solar activity runs in 11- to 14-year cycles, and “space-weather forecasting is still in its infancy, so we don’t always have much warning for specific events,” said Robert. “But we do know that the probability of a special event happening is higher during this period.”

Space-weather events impact aviation in multiple ways, including the degradation of radio and satellite communications, onboard system failures because of heightened radiation levels and a disturbance of global navigation satellite systems (GNSS) if radio signals are disrupted by ionospheric storms.

“A typical bad space-weather event happens several times each year, but the impact on infrastructures on earth is low,” said Robert. “Severe to extreme events that happen between one and five times during each solar cycle are more significant.”

In 1989, a space-weather event was the probable cause for the loss of four Navy satellites. In October 2003, the Wide Area Augmentation System was disrupted for nine hours. Two years later, solar activity impacted high-frequency communications across the U.S.

But there are inherent safeguards and practical ways to mitigate the potential disruptions of space weather. GNSS-based applications specify an unexpected loss or degradation of GNSS service in approach situations. “Onboard GNSS receivers monitor in real-time the performance of the service and will warn the pilot if GNSS-based operations have to be discontinued,” said Robert. “Pilots should always plan for a non-GNSS-based procedure as a backup at that destination or at the alternate airport.”

Robert said there is “some movement” within the aviation community to define new systems of alternative positioning, navigation and timing (PNT) to GNSS. “But this is only at the research stage and will only be ready in the longer term,” he added.

Current backup solutions are based on the use of conventional navigation aids like VOR, DME and ILS. Other alternatives include onboard inertial systems or radar vectoring by air traffic control.

Aircraft flying polar routes are particularly vulnerable to radiation storms, which can have an impact on the performance of instrumentation, including possible damage. Additional concerns are the unknown permanent impacts on passengers and crew. These events are the easiest space weather to track via the National Oceanic and Atmospheric Administration website.

Eurocontrol will hold a space-weather conference March 20 in Cologne, Germany, for aviation professionals interested in getting more information on this subject.