Did you ever wonder why cabin crew are so adamant on having you open your window shades during take-offs and landings? Why do the pilots dim the cabin lights for night take-offs and landings?
Read more learn about why your flight crew do so.
Why do window shades need to be raised during take-offs and landings?
Window shades are not raised just to provide the passenger with a better view on take-off and landing, it is also done for safety. Opening the window blinds is good for a combination of reasons:
It will give your eyes time to adjust to the light level outside
If it is a day flight, you will not emerge blinking from a darkened cabin into the bright sunshine, and if it is a night flight, you will be able to see better. (this is also the reason why the cabin lights are dimmed before landing at night time)
It increases situational awareness for all personnel on board
Raising the window shades allow cabin crew and passengers to spot any issues that can potentially save one’s life.
Dark and light adaptation
Our eye is a complex organ that sends signals to our brain of the environment beside us, and allows us to see things around us day and night. This is possible because of the presence of rhodopsin.
Light adaptation
Light adaptation occurs when we move from a dark area to a bright area. The bright light momentarily dazzles us and all we will see is white light because the sensitivity of the receptors is set to low light levels. The rods and cones in our eyes will be stimulated, resulting in large amounts of photopigment breaking down instantaneously, which will produce a flood of signals resulting in the glare.
Adaptation will occur in two ways:
The sensitivity of the retina will decrease dramatically
Retinal neurons undergo rapid adaptation inhibiting rod function and favouring the cone system
Within one minute the cones are sufficiently excited by the bright light to take over and visual accuracy and colour vision continue to improve over the next 10 minutes. During light adaptation, retinal sensitivity is lost.
Dark adaptation
Dark adaptation is the reverse of light adaptation. This occurs when one is going from a bright area to a dark area.
One will initially experience blackness as the cones in one’s eyes cease functioning in low intensity light and the rod pigments has originally been bleached out due to the bright light and the rods will be non-functional initially. Once in the dark, rhodopsin regenerates and the sensitivity of the retina increases over time which can take up to 1 hour. During this adaptation process, reflexive changes occur in the pupil size.
Therefore, window shades are raised and cabin lights are dimmed at night to create a cabin environment with light levels as close to the external environment as possible. This is to allow passengers and cabin crew eyes to get used to the light levels of the exterior environment, so that if any evacuation were to take place, passengers and crew members would not be dazzled by the light level changes, which can hinder the evacuation process.
Situational awareness
Another reason for raising the window shades is because is can help improve situational awareness of the cabin crew and passengers as they will be able to see what is happening outside of the aircraft. Since most aircraft accidents occur during take-off and landing, window shades are usually raised during those periods to prepare and alert the cabin crew and passengers of the situation.
With better situational awareness, abnormalities such as engine fire can be spotted more reliably, giving the crew and passengers on board ample time to prepare and execute emergency procedures if necessary. For example, if a fire ignites on the right wing of the aircraft, having the window shades open will alert the crew earlier and give them time to let everyone on board know that the evacuation if necessary will be done on the left side of the aircraft.
Although you might want to close the window shades to block out light from outside which can disturb your sleep, window shades should be kept open during the necessary periods for your own safety.
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