Forbush decreases have been registered onboard aircraft; an important dropdown of the aircraft crew exposure was stated. Particularly important effect of that kind was registered during the period of disturbed solar conditions at the end of October 2003, it was, however, already registered during 2001 year. The onboard dosimetry and geophysical data are presented and compared. Comparable decrease is observed for onboard measurements and geographically nearby cosmic ray neutron monitor’s data.
