A 91 kg (200 lb(m)) block of aluminized solid rocket propellant was burned in open air to simulate an accidental propellant fire. A suite of remote optical instruments measured the temperature and radiative properties of the plume. Solid molybdenum calorimeters provided data for heat flux estimates. Various refractory oxide and metallic witness samples placed in the fire provided temperature benchmarks and insight into how such samples may be dispersed by the fire. A thermochemical analysis assessed the overall energy balance. The results indicate that temperatures reached 3000 +/- 100 K and heat fluxes reached 200 +/-80W/ cm(2) under the propellant, which burned for 120 s, creating a severe environment.