Solar storms could expose airline passengers and crew to dangerous amounts of radiation, according to researchers at the University of Surrey. The study, published in the Journal of Space Weather and Space Climate, found radiation surges at typical flight altitudes.
Radiation at 40,000 feet
'Cosmic radiation at 40,000 feet is around 300 times higher than at sea level, giving a steady radiation drizzle,' Professor Clive Dyer, a visiting professor at the Surrey Space Centre and co-author of the study, tells Metro. 'Solar storms, however, can produce sudden downpours, potentially delivering a month's worth of this normal cosmic radiation in just one hour.'
Space weather describes the sun's activity, such as coronal mass ejections (CMEs) and the solar wind, a stream of particles travelling at a million miles per hour. The Earth is also exposed to cosmic radiation from exploding stars.
'These variations, particularly those from the sun, can influence life and technology on Earth and are what we call space weather,' says Professor Dyer. The Earth's magnetic field provides protection, but at 40,000 feet that protection is only one-third of what it is at ground level.
Impact on flights
'Long-haul aircrew typically receive around double the radiation exposure of someone at ground level for every year of flying and some frequent fliers spend even more time in the air,' says Professor Dyer. Powerful CMEs can cause geomagnetic storms, which can endanger spacecraft, disrupt power grids, and cause minor electronic errors in aircraft, known as Single Event Upsets (SEUs).
Last year, aircraft-maker Airbus grounded 6,000 A320 planes after intense solar radiation affected the flight control computer. The issue came to light after a JetBlue flight from Cancún, Mexico, to Newark, US, was forced to make an emergency landing in October 2025. The airline said the plane 'experienced an altitude drop' during the flight, injuring several passengers.
Extreme events and future planning
Severe solar storms are rare, occurring every few years. Professor Dyer cites one of the most extreme on February 23, 1956, when a plane at 40,000 feet would have been exposed to 1,000 times more radiation than normal. 'The cancer risk from flying through an event of this scale could be around one in 1,000,' he says, or about 'a year's worth of normal flight-related radiation in a single flight'.
Last November, three CMEs collided with Earth, causing a six-hour geomagnetic storm. Radiation jumped to almost 10 times normal high-altitude flight conditions, according to calculations by the Surrey Space Centre. Although just 2% as strong as the 1956 episode, Professor Dyer says it 'still produced significant radiation levels and indirectly led to aircraft being grounded and fixes being made'.
Researchers advise that while holiday plans need not be cancelled, aviation officials should account more for space weather. Forecasts can predict when a CME will hit Earth days in advance, and integrating these into flight planning could improve safety. An aviation-specific radiation scale could help air traffic control decide whether to reroute or ground planes. Polar flights, such as London Heathrow to Vancouver International, are particularly vulnerable due to weaker magnetic fields at the poles.
'We have been working on this problem for around 40 years, with significant progress made over the last decade as the dangers of space weather have become more widely recognised,' adds Professor Dyer. 'For individuals, the chance of being caught in an extreme event is low, but with growing air traffic, the hazard must be addressed.'
