Space Weather & Flight Safety
In May 2024, the most intense geomagnetic storm in 20 years — later named the Gannon storm — disrupted polar aviation for roughly 24 hours. Several European and Asian carriers rerouted or suspended polar sectors. Since then, two more G5-class events have struck. If you are flying polar routes during solar maximum, you may notice the effect. This guide explains what you are seeing and why it is not a safety issue.
What Is Space Weather?
Space weather is the collective term for conditions in the space environment between the Sun and Earth. The Sun releases energetic events — flares, coronal mass ejections, proton streams — that can reach Earth within minutes to a few days. When they do, the upper atmosphere and magnetic field respond in ways that affect radio communications, satellite navigation, and electrical systems on the ground.
Solar activity follows an 11-year cycle. Solar Cycle 25 reached its maximum in 2024–2025. During maximum, large geomagnetic storms occur more frequently. Three G5 "extreme" storms have been recorded so far in Cycle 25 (May 2024, May 2025, March 2026). In the preceding two decades combined, there was one — the Halloween storms of 2003.
What Does Space Weather Do to Flights?
Polar flights talk to ATC using HF radio because VHF does not reach across the polar cap. HF signals bounce off the ionosphere. During a solar flare, the ionosphere absorbs HF signals instead of reflecting them — a "shortwave fadeout". The fadeout can last from minutes to many hours. Aircraft switch to satellite communications.
The disturbed ionosphere scatters GPS signals. Receivers have more difficulty locking on and may show increased position uncertainty. At polar latitudes where GPS geometry is already weaker, the effect is more pronounced. Inertial Reference Systems, which do not depend on external signals, continue to work normally.
Solar proton events deliver energetic particles toward Earth. The magnetic field funnels them toward the poles. Polar-qualified aircraft have radiation dosimeters on the flight deck. During severe events, if readings approach operational thresholds, the crew may descend to lower altitude as a precaution — reducing dose and crew/passenger exposure. Typical passenger doses remain well below regulatory limits even during severe events.
For high-severity predicted events, carriers may pre-emptively reroute polar sectors to lower-latitude alternatives. This typically adds one to two hours of block time and some fuel. Passengers experience the same flight, slightly longer.
What Do Passengers Actually Experience?
On most flights during an active space weather event: nothing. Onboard Wi-Fi may run slower if the event affects satellite links, but in-cabin experience is otherwise unchanged.
On polar flights during a severe (G4–G5) event: possibly a longer routing chosen before departure, or occasionally a mid-flight re-filing to a lower-latitude track. Schedule adjustment of up to an hour or two. Aurora visibility from the window may be spectacular.
On rare occasions during extreme events: an outright sector cancellation or hold-before-departure. This is the exception, not the rule. During the Gannon storm, a handful of polar sectors were cancelled; the vast majority operated with modified routings.
Who Forecasts Space Weather for Aviation?
ICAO designates regional Space Weather Centres (SWXC) — currently NOAA SWPC in the US, Australia-Canada-France (ACFJ), Russia-China (RCC), and Japan (JASX) — that issue formal Space Weather Advisories to aviation. The advisories use a standardised format and thresholds, so dispatchers anywhere in the world see the same classification.
Carriers with significant polar operations maintain internal space weather teams or subscriptions to commercial providers. The operational response is mature and well-practised; Solar Cycle 25 has stress-tested the framework and it has performed.
Informational content only. Not flight planning or operational advice. Space weather forecasting and operational response are the responsibility of ICAO Space Weather Centres, national authorities, and operators. See Terms of Service.