According to NOAA Space Weather Scales [1], the effects of those events, their levels, and the corresponding hazards (including biological risks for the "S" category) are listed.
It is unclear to me what "high-flying" and "high latitudes" mean in these cases, and I would think that they would depend on the severity and location of the space weather event.
[0] https://www.swpc.noaa.gov/communities/space-weather-enthusia...
[1] https://www.swpc.noaa.gov/sites/default/files/images/NOAAsca...
Above FL410 is rare, except for business jets that can cruise that high. It comes with extra requirements on oxygen masks etc.
Polar routes are not that rare, but depend on certification how far away from a suitable airport you can go.
As a comparison, a typical flight might only have a dose of 40uSv, so like 25 normal flights. But still many people take many more trips than that.
Although it could also disrupt satellite communication causing some delays in flight planning and aircraft/crew turnaround.
For a fun anecdote, when the HF radio fault was reported we weren't aware of the troubles in the ionosphere. After a few hours of troubleshooting on the system and not finding any problems I flippantly remarked that it must've been a solar flare because the radios perfect. 15 minutes later I was reading the news and saw the headline.
https://old.reddit.com/r/sweden/comments/1cozkpa/blinkade_di...
But we have a weak grid anyway, so it might be unrelated.
This is a new excerpt from the news station "Primera Hora"
> "Por Primera Hora. 11 de mayo de 2024 • 7:53am. Las aurora borales que decoraron el cielo anoche se lograron ver en Puerto Rico, fenómeno que no se veía en la Isla desde hace 103 años"
English Translation:
>"For First Hour. May 11, 2024 • 7:53am. The northern lights that decorated the sky last night were seen in Puerto Rico, a phenomenon that had not been seen on the Island for 103 years"
- Power systems: Possible widespread voltage control problems and some protective systems will mistakenly trip out key assets from the grid.
- Spacecraft operations: May experience surface charging and tracking problems, corrections may be needed for orientation problems.
- Other systems: Induced pipeline currents affect preventive measures, HF radio propagation sporadic, satellite navigation degraded for hours, low-frequency radio navigation disrupted, and aurora has been seen as low as Alabama and northern California (typically 45° geomagnetic lat.).
https://www.swpc.noaa.gov/