Definitive answers to the questions readers ask most about in-flight cosmic radiation, the CARI-7 dose model, and our PDF report.
The CARI-7 / CARI-7A model used by the FAA has been validated against in-flight neutron and ionising-radiation measurements for several decades (see Friedberg & Copeland). The model's stated uncertainty for galactic-cosmic-ray-driven effective dose at typical cruise altitudes is on the order of ±25% at the 2σ level. We carry that uncertainty band through to the report — a value of "5.4 mSv/yr" should be read as roughly "4 to 7 mSv/yr".
A 14-page report with: per-segment effective dose, annualised total, polar-route attribution, a bar chart against ICRP-103 public limit (1 mSv/yr), FAA aircrew action level (6 mSv/yr), ICRP-103 occupational limit (20 mSv/yr averaged over 5 years), a 30-year career projection, and recommendations.
If the passenger profile is "pregnant" we also include the ICRP-103 §5.4.2 gestational fetus limit (1 mSv across the remainder of declared pregnancy) and a pointer to discuss the pattern with an obstetrician.
The CARI-7A web tool computes one segment at a time and returns one number with no context. FlightRadiation runs your entire flight log, sums it across a year, attributes the polar-route share, and places the total against the four ICRP-103 / FAA reference limits in a printable PDF. The underlying physics is identical — we are not a different model, we are different framing.
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, ICRP-103 §5.4.2, is 1 mSv to the conceptus across the remainder of pregnancy once it is declared — roughly 30 to 50 hours of transatlantic flying. 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.
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 and aircrew, polar segments are the single largest reducible exposure. In our sample report (Subject A) four polar crossings produced 38% of annual dose from 4.2% of segments. Where route choice exists, mid-latitude routings reduce dose meaningfully. See Polar routes and cosmic dose.
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.
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 FAA's 6 mSv/yr aircrew action level (NCRP 132 / AC 120-61B) is the more directly comparable number for frequent fliers.
No. The cosmic-radiation field at cruise altitude is highly penetrating and broadly isotropic; the fuselage skin and the few inches of aluminium between a window and aisle seat make no measurable difference. Window vs aisle is a comfort question, not a dosimetry question.
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 dose rate roughly 15 to 25%. See Lower altitude = lower dose.
No, not as a passenger. The ICRP-103 1 mSv/yr public limit is an international reference, not a US regulatory cap on cosmic-radiation exposure. The 20 mSv/yr occupational limit applies to radiation workers under regulatory frameworks like 10 CFR 20; it is not US-regulated for aircrew, though the FAA recommends a 6 mSv/yr action level via AC 120-61B. Some EU member states do regulate aircrew under the EURATOM Basic Safety Standards Directive (2013/59/Euratom).
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.
Under six hours for most reports; usually under one hour for single-segment or short flight logs. Multi-hundred-segment logs take longer because each segment requires its own CARI run.
We retain the flight log only as long as needed to produce and deliver the PDF, then delete it. We do not sell, resell or share flight logs. We do not connect logs to identity beyond the email address you used to order.
Last reviewed 30 June 2026 · Don't see your question? hello@flightradiation.com