text: An historical example, the Pratt & Whitney J58, illustrates the significance of using corrected values. 
  Rotating stall occurs at low corrected speeds so occurs during starting and also above idle. It may be relieved by opening a bleed valve to increase airflow. At very high flight speeds the compressor will return to this low corrected speed area so the same operating point occurs at low rotational speed on the ground and maximum rotational speed at mach 3 at high altitude. The stalling, low efficiency, blade vibration and failure that plagued low corrected speeds on the ground has returned at 100% rotor rpm at mach 3. The same operating point on the map has the same axial and peripheral mach numbers, same velocity triangles, same efficiency despite the actual rotor speed and compressor inlet temperature being 4750 RPM/60degF on the ground and 7,000RPM/over 600 degF at Mach 3. The same corrected operating point required the same solution to prevent stalling and increase efficiency which was to bleed air from the 4th compressor stage.