Modeling results and data are presented for a chemically reacting flow from a thrusting Atlas II rocket at low altitudes. High spatial resolution imagery and spectra have been obtained for a kerosene/liquid oxygen multinozzle plume at altitudes in the continuum flow regime. A numerical solution for a three-dimensional plume flow from the Atlas rocket engine is obtained using two different Navier-Stokes computational fluid dynamics codes. The influence of the flow near the rocket body on the plume structure is considered at an altitude of 40 km. The plume flowfields at 15- and 40-km altitudes are used for radiation calculations in the infrared spectral region. Calculated spectral radiant intensities and pixelated images are compared with the data extracted from the recent in-flight measurements. Comparison of the modeling with the data shows that numerical modeling is able to predict the plume structure existing at both altitudes. We find that it is necessary to include solid carbon particles as a radiating species to improve the agreement between simulated and measured radiation signatures.