The static coolant flow instability in a heated channel, sometimes called the Ledinegg instability, is manifested as a spontaneous “drift” of the steadystate operating parameters upon reaching the stability boundary. At the onset of static instability, the channel parameters acquire a new steady state. However, if static instability is developing along with the decreasing coolant flow rate, then either burnout conditions or oscillatory instability may develop in the channel (or the interaction between oscillatory and static instabilities may start with fluctuations of the channel pressure drop). An opportunity of the onset of oscillatory instability at the initiation of static instability should be taken into account when analyzing the experimental results of flow stability in power equipment. Cases are known [2] in which static instability was confused with oscillatory instability in conditions when self-oscillations of the coolant flow developed immediately after the short-term flow rate reduction.