Cabin Lights Dimmed for Landing- Why?

[charliegolf]

Genuine question, asked of me by a child. Why do they do that on night approaches? Pax get a better view!

Cheers

CG

[DeliBag]

Simply so your eyes get used to low light levels should there be an emergency.

[FLYING GER]

Hi there,

They switch them off or dim them as during the 'take off or landing roll' you may be required to evacuate. Should you need to evacuate, your eyes have been ajusted to the level of light outside. The purpose is so that if its dark outside, its dark inside and light outside light inside meaning that should you need to evacuate (unlikely and god forbid!) you dont have a blinding effect. ie. stepping out from light into dark which would make your eyes funny.

ALso the reason the window blinds must be up for take off/landing is so that should you need to evacuate the cabin crew can see outside and see if theres fire/smoke/obstructions so that they know whether to block off an exit and redirect you to an exit which doesnt have dangers outside.

If someone can explain it better then off you go as not very good at this!

[justD]

Yep! Exactly!
Can you see anything when you turn off the lights in your bedroom before you go to bed??? (well if it is dark outside...)

Windowblinds:
Have to be up also because the emergency services have to be able to look inside!

[sinala1]

Have to be up also because the emergency services have to be able to look inside!
The primary and only real reason is so that cabin crew can see outside the aircraft in the event of an evacuation... the ability for the emergency services to be able to see into the aircraft is an ancillary ability. If the emergency services need to be able to see inside, the chances are there is going to be gaping big holes for them to look through...

[Pax Agent]

At BA there is no requirement for the window blinds to be open.
The window blind is for the pax to do with as they wish.

[justD]

Sinala1

I merely completed the previous post!!!
Relax, I am fully aware of what the reason is behind the windowblind and lights issue. No need to explain.

[charliegolf]

Thanks everyone. Makes perfect sense.

CG

[GEAR_DOWN]

Pax Agent - At BA there is no requirement for the window blinds to be open.
The window blind is for the pax to do with as they wish.


well Obviously BA aren't concerned about your safety as other airlines are!!

[jet2impress]

Your eyes need to be adjusted to darkness for what may happen inside the cabin. If for example you suffer a problem on take off or landing which requires an evacuation. If the APU (Auxiliary Power Unit) is not running, when the engines are shut down prior to an evacuation, the cabin will be plunged into darkness. For this reason, your eyes need to be adjusted to the dark so you can get yourself to the exit. It does not matter if its dark outside, the fire from the burning aircraft will light your path! :eek:

[CrashAxe]

Why does it take so many people to say the same thing?

I think after the second post we realised it was to ensure that C/Crew can see an emergency outside of the aircraft.

It makes me laugh 'how many people it takes to change a lightbulb' so to speak! You've all said the same thing, just in different ways :-)

I bet you didn't anticipate this much of a response, did you CharlieGulf! :-)

:8

[GEAR_DOWN]

JET2IMPRESS - Why do you assume that there will be fire if you evacuate? I can think of many reasons why slides would be deployed without fire being present.

For example - Nose gear collapse ( southwest airlines yesterday ) no fire present but still evacuated as the attitude of the aircraft did not allow the safe positioning of steps to disembark pax.


Do not assume that there will be fire to ' light your path' away from the aircraft!!

I might also add thet the APU will never be running in an evacuation so the cabin will only have the emergency lighting as a power source, so always assume darkness.

[HAWK21M]

How long does it take to adjust to the higher Intensity lighting medically.
regds
MEL

[judge11]

So having 'adjusted' your eyes to lower light levels, you can then dazzle yourself (and the person next to you) by turning your 'individual reading light' on full blast thereby completely destroying any night-vision capability. Doesn't compute. I believe 'dimming the lights' is an urban myth that has just become 'the thing to do' over the years. Prove me wrong and come up with a reference from a national aviation authority, not an in-house airline manual, that requires the dimming of lights for take-off and landing. And I can assure you, there are many airlines that don't bother 'dimming'.

[jet2impress]

The fire statement was intended to be a joke. I was just making a point that your eyes need to be adjusted to darkness to be able to evacuate the aircraft. Other replies had said that you needed the night vision once outside the aircraft. :ouch:

[jet2impress]

Prove me wrong and come up with a reference from a national aviation authority, not an in-house airline manual, that requires the dimming of lights for take-off and landing. And I can assure you, there are many airlines that don't bother 'dimming'.

Taken from Chapter 32 of CAP 768:

"15, CABIN LIGHTING

The dimming of interior cabin lights, particularly when taking-off and landing at night is recommended."

As this is a recommendation, dimming of interior cabin lights at night is I guess, at the operators discretion only.

[Monkey Madness]

How long does it take to adjust to the higher Intensity lighting medically.

not sure on that, but It takes the average person between 30-45 mins to adjust their eyes from daylight/bright lighted room to night vision.

Hence CAP 768, Ch 32, Para 15.1 is only a recommendation.

[GEAR_DOWN]

Cabin lights should only be dimmed during the hours of darkness. Remember that the dimming of the lights during daylight hours may well lead to it being darker inside than it is outside!!!!

[ccguy]

Originally posted by sinala1
The primary and only real reason is so that cabin crew can see outside the aircraft in the event of an evacuation... the ability for the emergency services to be able to see into the aircraft is an ancillary ability. If the emergency services need to be able to see inside, the chances are there is going to be gaping big holes for them to look through...


I'm thinking that not all emergencies end with a gaping hole in a fuselage.

[missleadfoot]

I have no idea why but our procedures require us to dim lights (not off) for all take-offs and landings, day or night. Go figure. Maybe just a consistency thing however they do remain that way for the duration of the flight. The only time they are on high is for boarding and disembarking.

[sinala1]

I'm thinking that not all emergencies end with a gaping hole in a fuselage.
Correct, and thats not what I said or implied in my comment :)

[overhere]

As others who have studied human factors probably know, there are very limited benefits to either way (lights on or off).

Lights dimmed may offer a minimal increase in night vision - however it takes the human eye approx 20+ mins to gain full night vision and that is in a dark environment - not partially dimmed. The advantages are that it may slightly increase crew AND passenger night vision in an evac & may assist with control on the ground afterwards as passengers & crew will have improved vision - assuming they aren't surrounded by emergency vechiles with bright flashing lights or flames!

Lights on is statistically proven to increase the external visibility of the aircraft to other aircraft in terminal areas and therefore could possibly assist in preventing a mid air or ground collision - however with the high quality radar's now available at primary control zones and TCAS, these benifits are minimal.

Either way, it's not going to make a huge amount of difference, hense why it's not regulated by the FAA, CASA or CAA.

[Rwy in Sight]

How do you define dimming or rather how do you apply it? Do you keep on only the ceiling lights, only the "side" lights none at all and keep on only the seat belt and no smoking signs?

I have the feeling that a random set of light remains on and voila the dimming part is accomplished!


Rwy in Sight

[ShesGreatintheGalley]

on an A320 my favourite setting is Dim2 with the sidewall lights turned off. and for takeoff and landing (evening) all off.. just the aisle left on for night flying services. i like it dark. i think the passengers do to... late at night they just want to sleep... i think its nicer to be dark.. for the view taking off and landing and for those with young kiddies etc

[FA1]

I work for an Australian Airline and we leave it upto the Cabin Crew to decide if they want cabin lights on or off for take off and landing. I usually like to turn them on to wake any sleeping passengers.

Although if I am tired and down the back its a different story. Just kidding.

[Lovebird 25]

Cabin lights should be dimmed during night flights, if there is light in the cabin, nothing is visible outside, it’s a safety issue, and it takes several minutes until the vision is adjusted It's done during taxing for take off and for landing, before the gears come down. The galley lights must be completly off but the in the cabin, the window lights are dimmed 2. I guess each Airline has it's procedure.

But if a little girl askes me, I would probably say, "It's done for you, so you can see the city lights though your window."