Night Flights

[MarchRide]

I have been SLF on several night flights and wander why the cabin lights are dimmed for take off and landing. Could someone please explain, thanks.

[GlueBall]

It helps if there is an evacuation as one's eyes will already be adjusted to night vision.

[jrs2-benson]

Well, if an accident occurs shortly before, during or after TO, Crew/Passengers will have a reasonable amount of night sight.

JRSB.

[FireFoxDown]

Wow - always wondered that! I was told somewhere though that it was to give max power to the engines - i.e. instead of using a (small) portion of the engine power to power the lights ... (i realise that i probably couldn't explain that worse, but i hope you get the idea!) :O

[Bealzebub]

Answers one and two are right. Answer 3 would be a bit like turning off your car headlights whilst overtaking. Rarely is max power applied to the engines even during takeoff. Even when it is required there are much more important offloads such as the engine air bleeds ( eg airconditioning packs). In the event of an engine failure certain high load electrical items are automatically shed including part of the cabin lighting system. However the dimming of the cabin lights is performed by the cabin crew and is related to safety and comfort rather than aircraft performance.

[TightSlot]

The thread in this Window Shade Blinds thread in this forum @ http://www.pprune.org/forums/showthread.php?s=&threadid=112016 also covers a few more ideas on this subject in more detail, especially Boss Raptor who has an explanation that makes sense and that I hadn't heard before.

[Boss Raptor]

I think a combination of all the points are valid reasons for dimming the lights at night, I was told the 'comfort' reason on a BA SEP course many years ago.

I have taken some time to go through various industry papers and studies on evacuation (aero geek that I am), NTSB, CAA, Boeing, Accident Reports etc., and cannot find any particular study on evacuating at night. Although most evacuation studies seem to have been conducted in both day and night conditions.

An interesting extra set of points highlighted in these studies is that;

a) pax will move quickly towards a lighted emergency exit if they are in a dark environment, much quicker in fact than in daylight. And of course the emergency floor lighting is also part of this process.

b) pax will not take so long deciding which exit they are going to use, believe it or not some pax do apparently think 'I dont like the wing exit idea I'll go to the door instead'.

c) pax wont wait behind for their family/friends as they cant see them, apparently many building and aircraft fire deaths occur as people have waited behind for their mates/families.

d) in a smoke filled cabin with lights on the effect is like having your full headlight beam in fog, you cant see anything, and masks the exit lighting from being seen at a distance.