Solar flare radiation on polar flights: aircrew dose and alerts
Checked against the sources below on 29 October 2026. How these guides are written
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Most solar storms add little to crew dose; the events that matter are ground level enhancements (GLEs), and their extra dose falls almost entirely at high geomagnetic latitudes. Published estimates run from about 100 µSv for a 10-hour high-latitude flight at 40,000 ft during GLE 72 (September 2017) to modelled peaks of several hundred to about 3,600 µSv an hour at 35,000 ft in the polar region during GLE 69 (January 2005). ICAO RADIATION advisories trigger at 30 µSv/h (MOD) and 80 µSv/h (SEV).
Estimate your yearly dose without solar particle eventsThe calculator runs the Off Chocks app's model for the galactic cosmic ray dose from your hours, cruise level and routes.- NOAA solar radiation storm scale
- S1 to S5 by ≥10 MeV proton flux (10 to 100,000); S2 and above list radiation risk for high-flying crew at high latitudes
- S1 about 50, S5 fewer than 1 per 11-year cycle
- NOAA SWPC Space Weather Scales
- ICAO RADIATION advisory
- MOD at 30 µSv/h, SEV at 80 µSv/h effective dose rate
- MOD FL250 to FL460; SEV above FL250
- ICAO Doc 10100 (FAA InFO 20007)
- Quiet-sun background
- About 8 µSv/h at FL370 at very high latitudes; about a quarter of that near the equator
- Galactic cosmic radiation
- FAA InFO 20007
- GLE 72 flight dose
- About 100 µSv for a high-latitude flight at 40,000 ft lasting about 10 h
- 10 September 2017
- Mishev and Usoskin, Space Weather 2018
- GLE 69 peak dose rate
- About 230 to 3,600 µSv/h at 35,000 ft, polar, depending on the spectrum used; background 5.9 µSv/h
- 20 January 2005
- International GLE database (Oulu)
- Low and mid latitudes
- Above a cutoff rigidity of about 4 GV, galactic radiation was the larger source within 10 h even in the 1956 event
- GLE 5, 23 February 1956
- Copeland and Atwell 2019
- Advance dose estimate
- Not possible; no FAA program estimates SPE dose. Flying lower cuts exposure at high latitudes
- During an event
- FAA AC 120-61B
Solar flare, solar particle event or GLE?
A solar flare is a burst of X-rays, and on its own it is a radio problem: NOAA's R-scale for radio blackouts covers its HF and navigation effects on the sunlit side of the Earth. A solar particle event is the stream of energetic protons that can follow. The FAA's AC 120-61B describes it as a temporary increase in solar cosmic radiation that is "usually very small relative to the background rate from galactic cosmic radiation" but "on rare occasions" significantly greater, lasting "from a few minutes to more than a day".
The rare occasions are ground level enhancements (GLEs): events with protons energetic enough to raise neutron monitor counts at sea level. The international GLE database at the University of Oulu numbers them up to GLE 77 on 11 November 2025, with three in 2024 (11 May, 8 June and 21 November). Weaker events that raise only high-mountain monitors are logged as sub-GLEs.
How much extra dose on polar routes?
Latitude decides it. The AC says the increase "is greatest near the magnetic poles" and that solar particle dose rates "are negligible near the geomagnetic equator". Copeland and Atwell (Advances in Space Research, 2019) modelled the largest event of the neutron monitor era, GLE 5 in February 1956: doses at low geomagnetic cutoff rigidities (near the magnetic poles) could exceed recommended exposure limits, but where cutoff rigidity was above about 4 GV galactic radiation became the larger source within 10 hours at every altitude they examined, which suggests low and mid-latitude flights would be well protected.
For recent events the numbers are modest. Mishev and Usoskin (Space Weather, 2018) estimated about 100 µSv for a 10-hour high-latitude flight at 40,000 ft during GLE 72 on 10 September 2017. A normal long-haul sector is 30 to 80 µSv; the CARI-7 figure for New York to Tokyo in AC 120-61B is 55.1 µSv.
For big events the uncertainty is large. The GLE database lists modelled effective dose rates at 35,000 ft in the polar region for GLE 69 (20 January 2005) from several published spectra: peaks range from about 230 to about 3,600 µSv/h, against a galactic background of 5.9 µSv/h. For GLE 42 (29 September 1989) the same database gives peaks from about 2 to 93 µSv/h. The AC says an increase can last from a few minutes to more than a day; in the GLE 69 series the rate fell tenfold or more within about four hours, so the dose for a given flight depends on where it was and when.
How space weather warnings reach the flight deck
Since 7 November 2019, global space weather centres have issued advisories under ICAO Annex 3 on a rotating basis: SWPC (USA), the ACFJ consortium (Australia, Canada, France and Japan) and PECASUS (Europe). Australia's Bureau of Meteorology also lists a China and Russia consortium (CRC). A RADIATION advisory goes out at MOD for an effective dose rate of 30 µSv/h between FL250 and FL460, and at SEV for 80 µSv/h above FL250. Advisories name latitude bands (HNH is N90 to N60, HSH is S60 to S90), longitudes and the affected levels, for example "HNH HSH E180-W180 ABV FL350", with forecasts out to 24 hours.
NOAA's S-scale measures the flux of protons above 10 MeV near Earth. S1 (minor) lists no biological effect; from S2 (moderate) up, NOAA says passengers and crew in high-flying aircraft at high latitudes "may be exposed" to elevated radiation risk. NOAA lists HF radio effects through the polar regions at every S level, from minor at S1 to a possible complete blackout at S5, and ICAO issues separate HF COM and GNSS advisories.
What operators and crews can do
The FAA's AC 120-61B says the dose during a solar particle event "cannot be estimated in advance" and that no FAA program estimates it, while "flying at a lower altitude can significantly reduce radiation exposure in high-latitude areas of concern". Dose falls with lower altitude and lower latitude, so descent or a more southerly track are the levers.
Whether to use them is your operator's call, made through dispatch and its space weather procedures. If you flew a polar sector during a MOD or SEV advisory, ask your operator whether its dose record for you includes the event. The FAA's CARI-6 estimates galactic cosmic radiation only.
Mistakes pilots make
- Treating every flare headline as a radiation event. An R-scale radio blackout is an HF problem; dose rises only with a proton event, and mainly at high latitudes.
- Reading the S-level as your dose. The S-scale measures proton flux in space; the dose at your level depends on the energy spectrum, your altitude and the geomagnetic cutoff along the route.
- Assuming a mid-latitude flight takes the hit. Modelling of the largest event on record shows galactic radiation still dominating above a cutoff of about 4 GV.
- Assuming your dose record includes the event. The FAA's CARI-6 models galactic radiation only and the FAA says no FAA program estimates SPE dose, so ask how your operator's program handles it.
What Off Chocks tracks
- Off Chocks leaves solar particle events out of its radiation estimate. It models galactic cosmic radiation from route, a type-based cruise altitude, time aloft and a smoothed 11-year solar cycle.
- It scales dose by geomagnetic latitude from a dipole model of the Earth's field (the IGRF-14 pole for 2025) and does not work out cutoff rigidity along the route, so treat polar and high-latitude sectors as a rough guide. A sector flown during a GLE will read low; your operator's dose record is the reference.
Common questions
- Do solar flares increase radiation on flights?
- Only when a flare brings a solar proton event, and then mostly at high latitudes and high altitude. Most events add little against the galactic background.
- How much radiation do pilots get during a solar storm?
- About 100 µSv for a 10-hour high-latitude flight during the 2017 GLE 72. Larger events like GLE 69 in 2005 modelled at hundreds to thousands of µSv per hour near the poles, for short periods.
- What is a ground level enhancement (GLE)?
- A solar particle event energetic enough to raise neutron monitor counts at sea level. The latest, GLE 77, was on 11 November 2025 (GLE database, University of Oulu).
- What do ICAO RADIATION MOD and SEV mean?
- MOD is an effective dose rate of 30 µSv/h between FL250 and FL460; SEV is 80 µSv/h above FL250 (ICAO Doc 10100).
- Does flying lower reduce solar radiation dose?
- Yes. AC 120-61B says flying at a lower altitude can significantly reduce exposure in high-latitude areas during an event.
Sources
- NOAA Space Weather Prediction Center: NOAA Space Weather Scales
- FAA InFO 20007: Space weather advisories (23 October 2020)
- FAA Advisory Circular 120-61B: In-Flight Radiation Exposure
- International GLE database, University of Oulu
- Mishev A, Usoskin I. Assessment of the radiation environment at commercial jet flight altitudes during GLE 72. Space Weather 2018
- Copeland K, Atwell W. Flight safety implications of the extreme solar proton event of 23 February 1956. Adv Space Res 2019
This is general information from the published research and regulators, not medical advice. For your own situation, ask your aviation medical examiner, an occupational physician or your operator's radiation protection officer. Any estimate in Off Chocks is for your own awareness, not a dosimeter reading.