I fly for a living. When someone says “solar fix” for an A320, pilots picture the sun flipping a switch and the jet deciding to sail itself. Reality is messier. There are two separate problems that get lumped together under the banner of “radiation” - health exposure to people on board, and single-event effects in electronics. They overlap, but they require different responses. As a practical, operator-facing matter, the industry has leaned on procedures, warnings and component-level design choices rather than trying to wrap an airliner in lead. That reality shapes what a sensible A320 mitigation program should look like.

First the basics. Space weather information and advisories that explicitly include radiation at flight levels are part of the international aviation toolbox. ICAO established space weather advisories and a manual for their use so operators and crews can get forecasts and warnings about ionising radiation and other space-weather impacts affecting HF communications, GNSS navigation and radiation exposure at cruise altitudes. Those advisories are the operational first line of defence for flight planning and in-flight decisions.

What a lot of pilots do not realize is that short, intense solar particle events can sharply raise the flux of high-energy particles at cruise altitudes. Those particles can increase dose rates for crew and passengers during the event and, importantly for avionics, they produce single-event effects - bit flips, transient errors and sometimes latch-ups in semiconductor devices. The scientific literature and aviation reviews have documented that radiation at altitude is a real hazard to both human health and hardware performance, and that extreme events produce large short-term increases in dose and upset rates.

So why not just shield critical boxes? Two blunt facts make wholesale shielding impractical. First, effective shielding against high-energy particles requires mass. At typical cruise altitudes and energies relevant to solar energetic particles or high-energy secondary neutrons, you need significant areal density to attenuate the particle flux meaningfully. Adding that much mass to every avionics bay, flight control box and cable run is a weight, cost and certification problem that quickly becomes untenable for a commercial airliner. Second, shielding does not eliminate all single-event effects because some failure modes are caused by secondary particles produced in surrounding materials. The more practical and proven approach is hardened design and system-level mitigation - component selection, architecture and software strategies that tolerate or detect and recover from errors. The avionics standards and advisory material in common use reflect that approach.

Here is the inconvenient regulatory truth. The recognized hardware design assurance guidance used in civil aviation - RTCA DO-254 and EUROCAE ED-80 and associated FAA advisory circulars - focus on development assurance but historically provide limited specific, prescriptive guidance on assessing and mitigating single-event effects from atmospheric radiation. In fact, FAA advisory material acknowledges that SEE aspects are not fully addressed by the existing hardware AC. In practice that has left manufacturers and suppliers to manage SEEs through good engineering practice, radiation testing where appropriate, and the use of more robust device families or architectural redundancy.

What does that mean for an A320 “solar fix”? There are three pragmatic pillars you should expect and require from manufacturers and operators.

1) Immediate operational measures and use of space-weather advisories. Operators should integrate ICAO SWX advisories and national SWx services into dispatch and crew briefing workflows. For rare, strong events that drive particle flux up, sensible mitigation exists: reroute to lower latitudes, change altitude, delay flights where exposure or upset risk is unacceptable, or apply contingency procedures when GNSS or HF is degraded. Those are operational controls already supported by ICAO and national programs and they are the fastest way to reduce risk.

2) Hardware and software hardening for critical flight controls. For functions that affect flight path - flight control computers, sensor processing, and critical autopilot elements - the solution set is well known: select devices with known SEE performance, apply error detection and correction to memories, use redundancy and voting (for example triple modular redundancy in functions where practicable), design state machines to recover from invalid states, and add watchdog supervision. Vendors should provide tested SEE cross-sections for the actual parts used and document the mitigation architecture. White papers and vendor documentation make clear these techniques are standard practice in safety-critical design and often outperform brute-force shielding.

3) Fleet-level detection and traceability. Equip a representative sample of the fleet with dosimetry and instrumentation to compare modelled dose against real measurements in flight. Models for dose and upset rate vary and need validation with true flight data. The FAA, NASA and research partners have been working on improved nowcasts and models for aviation radiation specifically because the uncertainty in models impairs decisions. Operators should push for fitted instrumentation and data-sharing agreements so warnings and risk thresholds can be tailored to operational realities.

A practical checklist for operators and pilots

  • Demand transparency from OEMs and suppliers. For any critical box that can influence flight controls, require SEE test data, ECC strategy, and architecture-level mitigation descriptions as part of the equipment data package. Vendors must show how a single-bit upset is detected and contained, and what state the system enters if recovery is required.

  • Integrate SWX advisories into dispatch and crew briefings. Make space-weather products part of the standard go/no-go flow for polar and high-latitude operations. Crews should be trained to understand the operational implications of a MOD or SEV radiation advisory.

  • Equip selected aircraft with dosimeters and loggers. Start with a percentage of long-haul and polar aircraft and expand. Use the data to validate models and to inform pregnant-crew rostering and other occupational health limits. The public health agencies have been clear that aircrew are an exposed occupational group and that model and measurement improvements are needed.

  • Update emergency procedures and SOPs to include radiation-related contingencies: GNSS loss recovery, HF frequency plans, and in-flight options for altitude or route change when advised. These are cheap, fast and effective fixes compared with hardware campaigns.

What regulators must do

Regulators should close the gap between development assurance guidance and the realities of SEEs. That means clearer acceptability criteria for SEE testing where the function is safety-critical, and explicit requirements for vendors to present mitigations as part of certification substantiation. It also means treating high-energy particle flux as an operational risk variable in dispatch rules and allowing operators to factor SWX advisories into release decisions without onerous paperwork. The engineering community has mitigation tools. The missing piece is regulatory clarity and the operational adoption of SWX products.

Bottom line: there is no single “solar shielding” patch you can bolt on to an A320 to make it immune. Effective risk reduction blends three things - better operational use of space weather intelligence, architecture-level hardening of critical avionics, and fleet instrumentation so models become accurate. Pilots and operators should press for transparency, demand tested mitigations from suppliers, and treat space weather like any other operational hazard - forecast it, brief it, and have clear, practiced mitigations ready to go. That approach is lighter, faster, and far more reliable than trying to insulate an airliner from the sun.