This thesis explores various radiation transport toolkits to more accurately calculate pilot radiation exposure. Radiation exposure and its harmful effects on the human body are explored with the use of three simulation codes: DYASTIMA-R, MULASSIS, and HZETRN. Absorbed and equivalent dose values for seventeen different altitudes between 31,000 ft to 85,000 ft (9.5 km to 26 km) were simulated. Comparisons were made between HZETRN, which uses the deterministic method, and DYASTIMA-R and MULASSIS, which use the Monte Carlo method; all results were then compared to published data from ICRU Report 84. HZETRN and DYASTIMA-R output comparable results, with MULASSIS consistently outputting lower values. HZETRN results did not converge like DYASTIMA-R and MULASSIS results; this is probably due to the user-input source particle spectrum and the need to provide an extrapolated data set for HZETRN to base its simulations. HZETRN also neglected neutron particle influence on absorbed and equivalent dose which likely caused HZETRN dose values to undershoot. MULASSIS and HZETRN were further compared with previous studies in spacecraft shielding applications in deep-space and low Earth orbit environments. Results matched those of previous studies with MULASSIS underestimating dose values compared to HZETRN.