Ablative thermal protection systems (TPS) are mandatory for very high-energy re-entry, such as super-orbital or return from Moon exploration. Ablative TPS mitigate the heat flux through material decomposition and mass loss [1]. Nowadays, new materials, composed of a matrix of phenolic resin filled with carbon fibers [2] have been developed, e.g. light carbon composites, such as those designed in the US (PICA) and in Europe (ASTERM). The simulation of hypersonic flow in the presence of ablation requires the coupling between phenomena occurring in the gas phase (boundary layer) and in the solid phase (TPS). For example, gas chemical species diffuse toward the surface of the body while carbon compounds sublimate and interact with the gas in the boundary layer. As a consequence, the gas is "pushed away" from the surface (blowing effect) and thermochemical properties of the mixture strongly vary. Thus, an accurate evaluation of gas kinetics in the boundary layer plays a key role in the estimation of surface heat flux. Helber et al. [3] have found that some molecular CN states are in nonequilibrium. Spectroscopic measurements [3] on both graphite and carbon bonded carbon fiber material in the VKI Plasmatron facility suggest that the rotational and vibrational temperatures significantly deviate from equilibrium close to the ablating surface. The gathered data suggest that non-dissociated nitrogen in the boundary layer might play a relevant role in the vibrational excitation of the CN molecule, thus making a state-to-state (StS) approach suitable for the purpose of high-fidelity simulations [4]. In this work, a StS approach is proposed to analyze non-equilibrium phenomena which affect the dynamics of a nitrogen mixture, with particular attention to the CN molecule. A reference test case will be considered in order to untangle the question posed by Helber [3].