Aerospace giant Airbus recalling about half of its global fleet over a commercial plane's sudden altitude drop brings into sharp focus the importance of space weather in flight safety, even as experts raise questions about the company's analysis that a powerful solar flare caused damage to flight software.
An A320 aircraft unexpectedly lost altitude during a Mexico-US flight on October 30, injuring 15 passengers. In a statement on November 28, Airbus linked the incident to damage suffered by flight software due to "intense solar radiation".
Experts said intense cosmic radiation can cause "single-event upsets", which can corrupt data, but added that they found no significant solar event of concern on October 30.
Dibyendu Nandi, a space weather expert at the Centre of Excellence in Space Sciences India (CESSI) and Professor at the Indian Institutes of Science Education and Research (IISER), Kolkata, indicated in a post on X that there was no lack of a major space weather event that day.
"It is certainly not yet clear what transpired to lead to the fleet recall and updates. Assuming all other possibilities have been ruled out by Airbus aircraft carefully, I would lean towards cumulative space weather impacts, or a very rare energetic particle enhancement from galactic sources, manifesting during that specific October 30, 2025, Mexico-US flight," Nandi told PTI.
"An analysis of space weather data shows no significant solar event of concern on October 30, 2025," he said.
Previous "impacts" may have somehow escaped scrutiny from routine ground checks, Nandi added.
Solar storms periodically occur as the Sun's internal dynamo process, which creates its magnetic field, intensifies and weakens. A cycle of solar activity typically lasts 11 years. The Sun is now said to be at the peak of its heightened phase of solar activity in the current ongoing 'solar cycle 25'.
During a solar storm, a huge amount of charged particles, energy and magnetic fields can be suddenly discharged into the Solar System.
Asa Stahl, a US-based astronomer and science communicator, explained that when high-energy particles from the Sun strike aircraft computer chips, they can temporarily corrupt data, cause system malfunctions, or even permanently damage electronics.
Prasad Subramanian, faculty at the Indian Institute of Science Education and Research (IISER), Pune, told PTI: "Intensity of solar radiation during a solar flare, which is part of a solar storm, is high, which can cause 'single event upsets'. In other words, a '1' can be flipped to a '0' or a '0' can be flipped to a '1'."
Binary digits '0' and '1' are fundamental to computers and electronics, with '1' typically representing 'true/ON' and '0' representing 'false/OFF'. Any change to '0' and '1' instructions in devices central to keeping planes in flight can be catastrophic.
"Now, a piece of software is relying on the hardware to interpret its commands. You're making a software, believing that it'll work, believing that the electronic chip is going to obey and interpret a '0' as a '0' and a '1' as a '1'," he said.
"But here you have an energetic particle hitting the semiconductor device, causing an anomaly, or an abnormality. So in effect, it flips the bits and so the software doesn't do what it's intended to do," Subramanian said.
R Ramesh, senior professor at Bengaluru's Indian Institute of Astrophysics, added, "At the altitude of 30,000 to 40,000 feet above the Earth's surface, where commercial aircraft typically fly, the Earth's magnetic field, which shields the planet from energetic particles, weakens. This makes aircraft and satellites vulnerable to charged particles shot out by the Sun during flares and coronal mass ejections."
However, aircraft and flight electronics are designed for such possibilities. Stahl said, "Experts have known for decades that solar radiation could potentially cause the computers on aircraft to malfunction, so flight software is typically designed to automatically detect and correct for such disruptions."
Astrophysicists say that while it is plausible for energised, charged particles from a solar storm to cause serious damage to aircraft, there was a lack of clarity on Airbus's linking the damage caused to flight electronics on October 30 with solar radiation.
Subramanian said, "I checked the solar flare archives from October 29 to 31, and there were no major events reported on October 30. So, I'd say that it's not clear why Airbus thinks that the flight electronics could have been corrupted by a solar flare event."
"It's possible that a solar flare event that happened much earlier could have corrupted some of the electronics onboard, but the software malfunction made itself felt only later," he suggested.
Space weather is monitored by organisations worldwide to provide timely information on disruptions from the Sun that can possibly cause communication blackouts and satellite outages.
Nandi was part of a CESSI team that had predicted in 2018 that activity in the current solar cycle would peak in 2024. Its findings were published in the journal Nature Communications.
"This is the first time, to my knowledge, that there has been such a major recall of a global aircraft fleet because of risks linked to solar radiation," Stahl said in an email to PTI.
The recall by Airbus could well "set a major precedent" by signalling that space weather needs to be given more importance for aircraft safety, Stahl said.
"Solar activity poses real risks to important infrastructure that we depend on in our day-to-day lives, like cell service, GPS, or really anything that depends on satellites -- which is a lot. This incident is a reminder of that," the US-based astronomer added.