Among the questions our readers frequently ask about flight routines, the one about why cabin lighting is dimmed during takeoff and landing is second only to the one about the need to raise the window blinds!
Lights are not turned off to be less visible
Let’s start by dispelling three urban legends that are still commonplace.
No, the cabin is not dimmed so that the aircraft cannot be seen from the outside, making it an easy target for ill-intentioned people. In any case, its position lights remain on.
Nor are lights turned off to avoid disturbing airport neighbours! It’s easy to believe that engine noise can sometimes cause a certain amount of discomfort, but it’s not the cab lights that are going to light up the neighbors’ homes and keep them awake at night.
It is also said that this is to give the engines more power in the event of a go-around on landing, or to give them full power on take-off. This was true at one time, and still allows to keep a small reserve of power, but it’s not the real reason.
Lights are dimmed for safety reasons
It’s important to remember that most accidents occur during take-off and landing, and that these are critical moments in the flight cycle when safety conditions must be maximized.
The consequence of an accident during these phases of flight is often an evacuation of the aircraft under conditions that can be more or less complicated, which should take less than 90 seconds.
Now imagine you suddenly had to evacuate an aircraft at night, while you were in a very bright cabin. You’d be practically blind when you stepped out of the camera, as it takes 10 to 30 minutes for your eyes to adjust to the dark. If the terrain outside is rough, the environment hostile, and debris strewn across the ground, you won’t be able to move outside the aircraft.
10 to 30 minutes for eyes to adjust to darkness
That’s why we dim the cabin lights during take-off and landing: to get your eyes used to darkness in the event of an evacuation.
Another benefit of this practice: it makes the luminous floor markings that guide passengers to the emergency exits more visible.
The cabin’s light intensity is therefore reduced for the same reasons as the window blinds are forced open. Here it’s to get used to the dark, while in the other case it’s to get used to the light, that’s all.
Image : qatar airways cabin by night by Jordan Tan via Shutterstock
