Experiments have been conducted to study the transport and chemical kinetics mechanisms controlling the spread of flames over the surface of a thick solid fuel in an oxidizing gas flow moving in the direction of flame propagation (concurrent or flow assisted flame spread). In the experiments, the solid fuel (PMMA) is unchanged, but the oxidizer gas flow velocity, turbulence intensity and oxygen concentration, are systematically varied to determine their effect on the flame spread process. This is done by measuring the rate of flame spread, flame length, surface heat flux, exhaust gas temperature, products of combustion and soot.