Abstract
This paper studies the doses of cosmic radiatilon, to which commercial aircrew members are exposed, on the basis of actual flight data including flight times, altitudes and latitudes. The annual dose received on any single route was not more than about 4mSv, calculated assuming that a crew member was restricted to flying no more than 900h on that route. The dose of a single flight was less than 20μSv for 90.1% flights among all the flights. The seasonal variation of the dose was small enough to allow use of the annual average dose on a flight route throughout.
