The seat/occupant system was modeled geometrically and mathematically in this paper.The modified geometry model was closer to the real body.A numerical investigation using CFD technique was conducted.A three dimensional Reynolds-averaged Navier-Stokes code with standard turbulence model was used to describe the turbulent compressible flow field around the seat and occupant.The CFD code used was FLUENT

which is based on the control volume finite-difference approach.The results were presented in the form of force and moment coefficients

and agree well with the experimental data obtained from wind tunnel test.The dynamic characteristics of the seat / occupant system for Mach number of 0.2

0.6

and 1.2

at angles of attack from 0 to 60 degrees and the angles of sideslip from 0 to 30 degrees were investigated respectively.The results reveal that high Mach number

zero angle of the attack and large sideslip angle are the most dangerous state for the escaping pilot.