In this contribution we investigated the influence of a copper vapour on the radiative transfer in the air thermal plasma at the pressure of 1\,bar. We covered the entire spectrum ranging from pure air to pure copper vapour. The calculation of the radiative emission was done by calculating radiative flux divergence using discrete ordinates method (DOM). We also included net emission coefficients (NEC) for the comparison purposes. In simulations we used 24\,independent directions based on available computational power. The spatial integration was carried over fixed spatial step. The fixed temperature profile was used describing steady state plasma. The computed data suggested large impact of the copper vapour on the arc radiative properties. The radiative energy transfer increased by the factor of 3 while changing from the pure air to the pure copper vapour and assuming the same temperature profile. Larger portion of energy was also reabsorbed close to the plasma arc wall.