Flight personnel are likely to receive an effective dose of several mSv in 1 y of professional activity. In France, the order of 8 December 2003 requires airline companies to monitor the exposure of their flight personnel. This is why public authorities have made the SIEVERT system (a system for evaluating exposure to cosmic radiation in air transport), available to French airlines, to evaluate doses. The SIEVERT system has been operational for use by airlines since the start of summer 2001. So far, more than 2.5 million flights have been processed at the request of more than 30 French airlines. Furthermore, this system was opened to the public in March 2002 (http://www.sievert-system.org), so that every passenger can calculate the dose received during a flight. © The Author 2009. Published by Oxford University Press. All rights reserved.