In the case of an extreme, once-in-a-century solar storm, individual aircraft would not be the only ones affected, but the entire aviation sector, from traffic control to airports. Because of multiple backup systems, aviation safety would not be compromised, but the efficiency of the operation would suffer causing substantial economic losses and personal discomfort to passengers due to delayed and cancelled flights.
Radio bursts from the Sun and changes in the upper atmosphere can provoke large-scale radio blackouts, severely affecting the ability of aircraft and flight control to communicate. Such disturbances would be particularly severe for flights through the polar regions and over the oceans, where alternative communication options might not be available.
A solar storm would also impact the ionosphere, the upper layer of the atmosphere which, when disturbed, can seriously degrade radio communications and satellite navigation signals. Intermittent GNSS failures and positioning errors would take place, forcing aircraft to rely on backup navigation systems, such as gyroscopes and accelerometers, ground-based radio beacons, and paper charts.