In this research work the potential of rich quench lean combustion for low emission aeroengines is investigated in a rectangular atmospheric sector, representing a segment of an annular combustor. For a constant design point (cruise) the mixing process and the NO, formation are studied in detail by concentration, temperature and velocity measurements using intrusive and non-intrusive measuring techniques.Measurements at the exit of the homogeneous primary zone show relatively high levels of non-thermal NO. The NO, formation in the quench zone is very low due to the quick mixing of the secondary air achieved by an adequate penetration of the secondary air jets and a high turbulence level. The NO and CO emissions at the combustor exit are low and the pattern factor of the temperature distribution is sufficient.