When should altitude corrections be made on an Instrument Approach Plate if the temperature is below -30°C?

Altitude corrections should be made for all altitudes on an Instrument Approach Plate when the temperature is below -30°C due to the changes in air density that occur at lower temperatures. Specifically, cold temperature impacts the performance of aircraft, requiring adjustments to ensure safe operations. The colder the air, the denser it becomes, which affects an aircraft's lift and performance characteristics, necessitating a correction to the published altitudes in order to maintain the appropriate clearance and avoid any risk of terrain or obstacle encounters.

Making corrections to all altitudes ensures comprehensive safety during the approach phase of flight, as it accounts for critical factors such as obstacle clearance and approach minimums throughout the entire procedure. This practice is essential for maintaining safe altitude clearances, particularly in colder climates where temperature deviations can significantly affect aircraft behavior and performance.