Approaches for identifying precursor events to lean blowout (LBO) in premixed or partially premixed combustors have been examined. This work characterizes the behavior of a premixed, swirl stabilized dump combustor near the lean blowout equivalence ratio limit using chemiluminescence (optical) and acoustic radiation emissions from the combustor. The results show that the transient behavior of the flame as lean blowout is approached can be characterized by short duration, localized extinction and reignition events. These events increase in frequency and duration as LBO is approached. Several methods based on signal thresholding, statistical analysis and frequency analysis are presented to transform the raw sensor output into a simple LBO proximity measure for use in an active control system. The thresholding approach utilizing the optical sensor provides the fastest time response. The sensor requirements for such systems are also presented, and it is shown that they can be met with practical devices. © 2002 by T. M. Muruganandam, S. Nair, Y. Neumeier, T. Lieuwen and J. Seitzman.