What level should cockpit illumination be set to for optimal night vision?

For optimal night vision, cockpit illumination should be set to the lowest easily readable level. This practice is essential because bright lights can significantly impair a pilot's ability to see outside the cockpit during the night. The human eye takes time to adjust after exposure to bright lights, making it crucial to minimize interior lighting to maintain night vision acuity.

Using the lowest level of illumination that still allows for effective reading of instruments helps preserve the pilot's dark adaptation, which is necessary for detecting other lights and visual cues outside the aircraft. This approach not only enhances safety during night operations but also supports better situational awareness by allowing the eyes to remain adjusted to the darkness outside. Therefore, setting cockpit illumination to the lowest easily readable level is vital for effective night flight operations.