Frequently asked

Definitive answers to the questions readers ask most about in-flight cosmic radiation, the CARI-7 dose model, and our PDF report.

• How accurate is the dose number on a FlightRadiation report?

  Two things go into the range on your report. CARI-7 itself was compared against instruments flown on real aircraft by Meier et al. (2018), which showed per-point deviations from -8% to +11%, with the authors putting the model's upper limit of uncertainty at about 20%. Separately, this site's own agreement with the 27 route doses the FAA published is 13.3% mean absolute deviation when you supply the cruise altitude and flight time and 17% when we estimate them, measured on flights the model was not fitted to. Reports carry ±25% or ±30% accordingly. These are coverage figures, not confidence intervals.

• What does the PDF actually contain?

  Every flight you entered, with its effective dose in microsieverts and an annual total for the itinerary, each given as a range. A table of everyday comparisons (chest X-ray, mammogram, head CT, a year of natural background) and the ICRP-103 public reference level, the FAA aircrew action level and the occupational limit. A breakdown showing the cutoff rigidity, average dose rate and solar conditions behind each flight. And a provenance table listing the model version, the cutoff grid and the months of solar data used, so the figures can be checked.

  If the passenger profile is set to pregnant, the report compares your itinerary against the 1 mSv figure that applies across a pregnancy, explains that this is an occupational protection limit rather than a clinical threshold, and cites the ACOG Committee Opinion 656 reference of 50 mGy alongside it.

• How is this different from running CARI-7 yourself?

  The FAA's public web calculator has been unavailable for some time, and its own page says so. What the FAA still distributes is CARI-7 as a Windows or Linux download, with no macOS build. We run that same model, so the physics is the FAA's rather than ours, and we add what a download does not do: a whole year of flights rather than one sector, the solar conditions for the months you actually flew, an uncertainty range, and the comparisons that make a microsievert figure mean something.

• Is flying during pregnancy dangerous?

  For occasional flying, no. ACOG Committee Opinion 656 notes that cumulative fetal exposure below 50 mGy has not been associated with an increase in fetal anomalies or pregnancy loss. For comparison, a single transatlantic round trip is on the order of 0.1 mSv to the fetus.

  The relevant occupational reference is 1 mSv to the conceptus across the remainder of a declared pregnancy, which at typical transatlantic dose rates is roughly 240 hours in the air. Frequent flying during pregnancy is worth a discussion with an obstetrician, and for crew with the employer's radiation-safety officer. See our detailed guide: Pregnancy and flying.

• Should I avoid polar routes?

  For most fliers, no. A typical leisure flier doing one or two transatlantic trips a year is exposed well below the ICRP-103 public 1 mSv reference even if both crossings are polar.

  For frequent fliers, polar routings carry the most reducible dose, because geomagnetic shielding falls off steeply north of 60° latitude. Where you have a choice of routing, a more southerly, mid-latitude flight reduces the dose meaningfully. See Polar routes and cosmic dose.

• What is a solar particle event and should I worry about it?

  A solar particle event (SPE) is a burst of high-energy protons accelerated by a solar flare or coronal mass ejection. Large SPEs (NOAA S3 or above) can deliver doses to a polar-cruising aircraft comparable to weeks of normal GCR exposure in a few hours. They are rare (typically a handful of S3+ events per 11-year solar cycle) and aircrew dispatch already includes SPE response procedures.

  As a passenger, you cannot meaningfully avoid SPEs through booking decisions. For frequent fliers, total lifetime contribution from SPEs is small relative to baseline GCR. See Solar particle events.

• Why is the public reference level 1 mSv/yr if a transatlantic round trip is 0.1 mSv?

  The ICRP-103 1 mSv/yr public limit applies to dose from controllable sources, practices subject to societal control like nuclear power generation. Cosmic radiation is explicitly excluded from the 1 mSv limit as a natural-background contribution. We nonetheless display the 1 mSv reference on the report because it is the most familiar benchmark of "small additional dose". The 6 mSv/yr level at which EU rules require airlines to manage crew rosters (Directive 2013/59/Euratom, Art 35(3)) is the more directly comparable number for a frequent flier.

• Does the window seat matter?

  No. The cosmic-radiation field at cruise altitude is highly penetrating and broadly isotropic; the fuselage skin and the few inches of aluminum between a window and aisle seat make no measurable difference. Window vs aisle is a comfort question, not a dosimetry question.

• Does the type of aircraft matter?

  At the precision CARI-7 supports, no. Differences between common civil airframes at the same flight level on the same date are within the model's uncertainty band.

  What does matter is cruise altitude. A step climb from FL350 to FL410 raises the dose rate by about 46%. See Lower altitude = lower dose.

• Are the dose limits on the report regulatory limits I'm subject to?

  No, not as a passenger. The ICRP-103 1 mSv/yr public reference level is an international benchmark, not a US regulatory cap on cosmic radiation exposure. The 20 mSv/yr occupational limit, averaged over five years, comes from ICRP-103 and is echoed in FAA AC 120-61B, which also recommends no more than 50 mSv in any single year; neither is enforced for US aircrew. The 6 mSv/yr figure often quoted is not the FAA's. It is the level at which EU rules require airlines to manage crew rosters, under Directive 2013/59/Euratom.

• Can I use this for a job-related dosimetry record?

  No. FlightRadiation reports are educational. They are not a certified dosimetry record. If you are aircrew and need a record for occupational-health or insurance purposes, your employer is recommended (in the US under FAA AC 120-61B) or required (in EURATOM jurisdictions) to provide one.

• How long until I get the PDF?

  The report is generated the moment your payment clears and emailed to you, normally in under a minute. You can also download it straight from the confirmation page.

• Do you store my flight details?

  We keep the flights and email address you entered against your order, because they are what the report is made from and we need the record for accounting. We do not sell, resell or share them, we do not connect them to any identity beyond the email address you ordered with, and you can ask us to delete your order record at any time by emailing us. See the privacy page for the detail.

Reviewed 4 September 2026 · Don't see your question? hello@flightradiation.com