Methodology
Every number on a FlightRadiation report is produced by running the flight through the FAA CARI-7 / CARI-7A cosmic-radiation transport model and weighting the output with ICRP Publication 103 tissue weighting factors. This page documents the model, the inputs, the derived metrics, and the uncertainty bounds.
1. The transport model: CARI-7 / CARI-7A
CARI-7 is the seventh-generation cosmic-radiation transport code published by the FAA's Civil Aerospace Medical Institute (CAMI) in Oklahoma City. It replaced CARI-6, which had been the regulatory reference since the late 1990s. CARI-7 differs from CARI-6 in that it uses Monte Carlo particle transport (MCNPX-based) and includes secondary particle production (neutrons, muons, electromagnetic cascade) explicitly rather than via tabulated parameterization.
The publicly maintained interactive version, CARI-7A, accepts origin and destination airports (IATA or ICAO), a cruise flight level, departure date, and aircraft type. It returns effective dose for that single flight in microsieverts. We compute the single-flight dose from the same physics tables and great-circle routing logic documented in Copeland's CARI-7 / CARI-7A documentation (see sources), then wrap it in plain-language context.
2. The dose quantity: effective dose (E), ICRP-103 weighted
The CARI series outputs effective dose, denoted E, in sieverts. Effective dose is not a measurement; it is a calculated whole-body equivalent that accounts for (a) the radiation type's biological effectiveness via radiation weighting factor wR, and (b) the differential radio-sensitivity of organs via tissue weighting factor wT. We use ICRP Publication 103 (2007) wT values, which superseded ICRP Publication 60 (1990).
The key ICRP-103 wT revisions from ICRP-60: gonads dropped from 0.20 to 0.08, breast rose from 0.05 to 0.12, brain raised explicitly to 0.01 (was in the remainder under ICRP-60). For typical cruise altitudes and mixed cosmic-ray fields, ICRP-103 weighting yields E values within roughly 10–15% of ICRP-60 weighting for the same physical fluence, but the direction of the correction depends on the radiation field composition. We always cite ICRP-103.
3. Inputs we accept
The whole form is one flight, with no account to create.
- Origin and destination. IATA airport codes; we map to lat/long internally using a static OpenFlights-derived table and compute the great-circle route.
- Cruise altitude. A flight level (FL250–FL420). This is the single largest driver of dose rate.
- Flight time (optional). If you leave it blank we estimate it from the great-circle distance at typical cruise speed plus taxi and climb. If you know the block time, enter it and we use yours.
- Times per year (optional). A multiplier. If you fly this route regularly, we annualize the single-flight dose by this number and place the total against the 1 mSv public reference level.
- Passenger profile. Adult / child / pregnant. Adult is the default ICRP-103 reference person. Pregnant invokes the 1 mSv gestational reference level and a recommendation to consult an obstetrician.
4. Derived metrics on the report
The PDF contains the following derived quantities, each computed as documented below:
| Metric | How we compute it |
|---|---|
| Single-flight effective dose (µSv) | CARI-7 output for the route (O/D great circle) at the route's cruise altitude, integrated over the flight time. Round-trip is twice the one-way figure. |
| Everyday comparisons | The flight dose placed against a chest X-ray (~100 µSv), a dental bitewing (~5 µSv), and a year of US natural background (~3 mSv), from ICRP and NCRP-184 reference tables. |
| Annualized dose (if a frequency is given) | Single-flight dose × times-per-year. Reported in mSv and placed against the ICRP-103 public reference level of 1 mSv/yr. |
| ICRP-103 reference-level comparisons | The flight (and annualized total, if given) against (a) ICRP-103 public 1 mSv/yr, (b) pregnancy 1 mSv across gestation, (c) FAA aircrew action level 6 mSv/yr (NCRP Report 132 / FAA AC 120-61B), (d) ICRP-103 occupational 5-yr averaged 20 mSv/yr. |
| Pregnancy note | For a pregnant traveler: the flight and any annualized total compared against the ICRP-103 fetus reference of 1 mSv across the remainder of pregnancy (ICRP-103 §5.4.2), with a pointer to consult an obstetrician (ACOG Committee Opinion 656). |
5. What we deliberately do NOT compute
- Individual cancer risk. Lifetime attributable risk (LAR) per Sv is published in BEIR VII (NAS, 2006) and ICRP-103, but applying a single LAR coefficient to an individual is statistically unsound and we will not do it. Risk depends on age at exposure, sex, dose rate, prior exposures, and competing causes of death.
- SPE dose. Solar particle events can deliver doses comparable to weeks of flying in a few hours, but the magnitude depends on the specific event spectrum and the aircraft's location at the time. We flag any user-supplied flight dates that overlap a NOAA SWPC-listed SPE and recommend the operator's incident report be consulted.
- Aircraft shielding differences. CARI-7 assumes a generic civil-aviation airframe. Differences between, say, an A220 and an A380 at the same FL are within the model's stated uncertainty band and we do not break them out.
6. Known uncertainty bounds
The CARI series has been validated against a large set of in-flight neutron and ionizing-radiation measurements (Friedberg & Copeland and colleagues, multiple decades of papers; see sources). The model's stated uncertainty for galactic cosmic-ray-driven effective dose at typical cruise altitudes is on the order of ±25% (2σ) when compared to instrumented measurements. We carry this band through the report: a value of "5.4 mSv/yr" should be read as "approximately 4 to 7 mSv/yr at the 2σ level". The polar-route attribution metric is less precise because the geomagnetic-cutoff transition is gradual rather than a hard 60° step, but the qualitative finding (polar segments dominate transatlantic dose) holds across implementations.
7. Data refresh cadence
The CARI-7A heliocentric-potential tables are updated by FAA CAMI as new neutron-monitor data become available. We pull the latest published tables monthly. The ICRP-103 weighting factors are static; ICRP-103 has been the operative recommendation since 2007 and a successor publication is not yet in force. NCRP Report 160 background-dose values reflect 2006 US-population averages and have not been formally superseded.
8. Reproducibility
Every report PDF lists the exact CARI-7A version used, the heliocentric potential table month, and the ICRP-103 wT set. A reader with access to the public CARI-7A web tool can reproduce every number on the report.
FlightRadiation reports are an educational dose estimate. They are not a medical diagnosis, an occupational dosimetry record for regulatory purposes, or a substitute for an employer's dosimetry program. We are not affiliated with the FAA, ICRP, NCRP, NOAA or any other agency. If your work or health situation depends on a certified dose record, consult your employer's radiation-safety officer or an occupational-medicine physician.
Reviewed 24 May 2026 · See our sources