EXPOSURE TO COSMIC-RADIATION OF BRITISH-AIRWAYS FLYING CREW ON ULTRALONGHAUL ROUTES

British Airways has carried out radiation monitoring in Concorde for m ore than 20 years and has used a heuristic model based on data quoted by the National Aeronautics and Space Administration (NASA) to model r adiation exposure in all longhaul fleets. From these data it has been calculated that no flight deck crew would exceed the control level of 6 mSv/y currently under consideration by regulatory authorities, which is three tenths of the occupational dose limit of 20 mSv/y recommende d by the International Commission on Radiological Protection (ICRP). T he model suggested that less than 4% of cabin crew based in Tokyo flyi ng only between London and Japan could reach or exceed the 6 mSv/y lev el, based on a predicted effective dose rate of 7 mu Sv/h. To validate this calculation a sampling measurement programme was carried out on nine round trips flown by a Boeing 747-400 between London and Tokyo. T he radiation field was measured with dosimeters used for routine perso nal monitoring (thermoluminescence dosimeters (TLDs) and polyallyldigl ycol carbonate neutron dosimeters). The limitations of the methodology are acknowledged, but the results indicate that the effective dose ra te was 6 mu Sv/h which is consistent with the predicted effective dose rate of 7 mu Sv/h, This result, which is in accordance with other rep orted studies indicates that it is unlikely that any of the cabin crew based in Tokyo exceeded the 6 mSv/y level. In accordance with ''as lo w as reasonably achievable'' principles British Airways will continue to monitor flying crew routes and hours flown to ensure compliance.