The apparition of compression system instability has plagued designers throughout the history of gas turbine development. The region where these instabilities are encountered is demarcated on the compressor performance map by a barrier, referred to as the surge line, that separates the regions of stable and unstable operation. Current generation turbomachines must allow for a safety margin, known as the surge margin, which places the operating point in a region far enough removed from the surge line so as to prevent the onset of instability.