What is the recommended procedure if you encounter the negative effects of compressibility?

When encountering the negative effects of compressibility, the recommended procedure is to reduce speed. Compressibility effects become more pronounced as an aircraft approaches transonic speeds, which can lead to a reduction in control effectiveness and an increase in drag. By slowing down, the aircraft can operate at a speed where compressibility effects are minimized, helping to maintain better control and performance.

Maintaining altitude or ascending may not address the underlying issue of increased drag and potential loss of control associated with compressibility. Similarly, speeding up would exacerbate the negative effects and increase the risk. Thus, slowing down is the most effective strategy for mitigating the complications arising from compressibility at high speeds.