At the beginning and end of a flight, or when it is dark outside, cabin lights are often turned off and passengers are asked to close the window shades. The lights in the cabin are typically dimmed when the plane is on the runway preparing for takeoff and the process repeats at the end of the journey, signaling an imminent landing. According to Simple Flying, the primary reason behind this practice is the safety of passengers and crew.
One key reason for turning off the cabin lights and asking passengers to close the window shades is to ensure safety in the event of an emergency. Ideal vision can make a significant difference in such situations, and allowing the eyes to adjust to low light conditions can be critical for a safe evacuation. By having passengers close the window shades, they are better able to determine their surroundings and direction during an emergency.
Turning off the cabin lights also allows passengers and crew more time to adjust to low light conditions, which is essential if an evacuation is needed at night. The human eye takes time to fully adjust to darkness, and this adjustment period can impact the chances of a successful evacuation. Additionally, by keeping the cabin dark, emergency lights and illuminated aisles are more visible, aiding in a quick and safe evacuation.
In most cases, emergency situations do not occur, but turning off the cabin lights during takeoff and landing can also help reduce the aircraft’s power consumption, optimizing engine performance during critical phases of flight. Overall, the practice of turning off cabin lights and closing window shades is a safety measure aimed at ensuring the well-being of passengers and crew during flights.