An avoidance system for avoiding an impending stall or surge in a radial compressor, comprising: a detection system, comprising a plurality of detection devices coupled to the radial compressor, at least a portion of each detection device disposed in a diffuser channel of a diffuser of the radial compressor, the plurality of detection devices configured to detect a transition of a low momentum zone of a gas flow through the diffuser from a first position adjacent a shroud wall of the diffuser to a second position adjacent a hub wall of the diffuser, and a control system electrically coupled to the plurality of detection devices and configured to receive a plurality of information signals, each information signal being transmitted by a respective one of the plurality of detection devices and correlating to a location of the low momentum zone, the control system further being configured to process the plurality of information signals and detect the impending stall or surge based on the location of the low momentum zone; and a bypass valve electrically coupled to the control system and in fluid communication with the radial compressor, wherein, the control system is further configured to generate and transmit a command signal to the bypass valve based on the location of the low momentum zone, and the bypass valve is configured to receive the command signal and vary the amount of the gas flow into the radial compressor based on the command signal. a detection system, comprising a plurality of detection devices coupled to the radial compressor, at least a portion of each detection device disposed in a diffuser channel of a diffuser of the radial compressor, the plurality of detection devices configured to detect a transition of a low momentum zone of a gas flow through the diffuser from a first position adjacent a shroud wall of the diffuser to a second position adjacent a hub wall of the diffuser, and a control system electrically coupled to the plurality of detection devices and configured to receive a plurality of information signals, each information signal being transmitted by a respective one of the plurality of detection devices and correlating to a location of the low momentum zone, the control system further being configured to process the plurality of information signals and detect the impending stall or surge based on the location of the low momentum zone; and a plurality of detection devices coupled to the radial compressor, at least a portion of each detection device disposed in a diffuser channel of a diffuser of the radial compressor, the plurality of detection devices configured to detect a transition of a low momentum zone of a gas flow through the diffuser from a first position adjacent a shroud wall of the diffuser to a second position adjacent a hub wall of the diffuser, and a control system electrically coupled to the plurality of detection devices and configured to receive a plurality of information signals, each information signal being transmitted by a respective one of the plurality of detection devices and correlating to a location of the low momentum zone, the control system further being configured to process the plurality of information signals and detect the impending stall or surge based on the location of the low momentum zone; and a bypass valve electrically coupled to the control system and in fluid communication with the radial compressor, wherein, the control system is further configured to generate and transmit a command signal to the bypass valve based on the location of the low momentum zone, and the bypass valve is configured to receive the command signal and vary the amount of the gas flow into the radial compressor based on the command signal.