Air carrier crews are occupationally exposed to ionizing radiation, principally from galactic cosmic radiation. To promote radiation safety in aviation the Federal Aviation Administration has: issued educational material on the nature of the radiation received during air travel; recommended radiation exposure limits for pregnant and nonpregnant aircrew members; developed computer programs that estimate for a given flight profile the amount of galactic radiation received on a current flight or on one flown at any time back to January 1958; published tables that enable aircrew members to estimate possible health risks associated with their occupational exposure to radiation; and conducted research on effects of radiation during pregnancy. References for this material are given in the article. In addition, graphic and tabular data in the article show how galactic radiation levels and the composition of the galactic radiation has changed between 1958 and 1999. Also given are estimates of effective doses received by air travelers on a wide variety of air carrier flights.