I wondered for a long time why the light inside an aircraft is always turned off when taking off or landing.
2 Answers
In case of emergency (which is more likely during take offs and landings) people should be prepared just in case. So during daytime, opening window shades and putting cabin lights to full makes the eyes used to sunlight so if something goes wrong and passengers need to be evacuated there will not be sudden change in light contrast which might lead to temporary blurred vision.
Same thing at night flights, window shades are open and cabin lights are dimmed.
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2I believe the opening of window shades is largely intended to enable passengers to identify hazardous conditions before they leave the plane. If you can see the fire off the port side of the plane, you'll know to use the starboard exits for evacuation.– phoogCommented Dec 23, 2015 at 2:21
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1@phoog and also, of course, so people outside can see in. Maybe a better question is why some airlines insist on lying about the reason (i.e. Cebu Pacific's recorded message say's they're adjusting the lights "so you can enjoy the view better" -- or at least it used to). Yes, I know why they lie but they could go what other airlines do and say "per regulations ..."– SpaceDogCommented Dec 23, 2015 at 4:25
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I have also heard (privately from cabin crew and pilots) that this is also done these days (along with turning off the tail logo light) to avoid getting attention during night time landings - especially when flying into hostile areas. There were a few incidents where airplanes were fired upon during landing. Commented Dec 23, 2015 at 5:39
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3@BurhanKhalid - that's almost certainly an urban myth... there's not much point turning off your tail light when your landing lights are making you look like a christmas tree in a high visibility vest! Commented Dec 23, 2015 at 11:46
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1@BurhanKhalid Tail lights are the ones that shows which airline it is.. and these have a dedicated switch in the cockpit, and yes they might be switched off in some cases I assume.. Cabin lights have nothing to do with that and they are directly related to the safety of passengers in case of crash landings or emergency landings.. Commented Dec 23, 2015 at 19:44
Cabin lights interfere with vision out of the plane for flight crews. They cast a night time reflection and glare that affects them, but also affects uptake of actual navigation lights by others, such as collision and landing lights. With the cabin lights on, the collision and landing lights are difficult to pick out, especially from the air by other planes.
As a secondary consideration, power on takeoff is better spent by the engines and other systems than by lights in the cabin.