ABSTRACT
Cosmic radiations from outer space are continuously exposing the earth. Ambient dose rate at the atmosphere, apart from unusually and transient solar activities, is mostly a function of latitude and altitude. At aircraft altitude and temperate latitudes, it increases by a factor of 20-25. Therefore, aircrew and frequent flyers are exposed to high levels of cosmic radiation. This paper considers general radiation protection aspects of cosmic radiation exposure to aircrew in domestic flights in Iran. Ambient dose rate in several domestic flights was measured using survey meter model RDS-110. Based on the measured data and duration of the flight, the effective doses of the aircrew were calculated and compared with that derived from radiation transport codes of CARI-6 introduced by Civil Aerospace Medical Institute, Oklahoma City, USA. Due to good agreement between measured and calculated values, the CARI-6 program was used to determine the dose rates in different altitude throughout the country to provide a simple algorithm for calculating route dose in domestic flights. Equivalent dose rate in domestic flight's altitude can be calculated from, a[h]b where h is the altitude in thousand feet; a and b are constants depending to geographic location. Based on the equivalent dose rate and the flight profile; simple algorithm provided to estimate the route dose in any domestic flights. The annual dose limit of general population allows the aircrew to spend 290 hour in 27-33 thousand feet altitude in domestic flights; therefore, only female aircrew should be made aware of the need to control doses during pregnancy