Why do the lights go out?
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Why do the lights go out?
Hi Guys, this is a question to all you pilots out there. I am a student pilot. I was wondering why is it, that when an aircraft( a passenger airliner) is taking-off or landing at night that the cabin lights are turned right down to very dim, and then once airbourne they are turned up again. Is this some strange safety measure. No explanation of this was presented in any of my ATPL courses. Please explain. Thanks.
Smoothk
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I think its usually so the passengers eyes can adapt to the low light so in the event of an emergency or accident and an evacuation is nescessary you can see your way to the nearest exit more easily because the cabin at best would be very dim at night if the aircraft had sustained damage in an over run or something similar. Although not all airlines have the policy some have the lights on max for takeoff and landing, reason being rescue services can see the aircraft more easily if an accident occurs, hmm
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Can't fault AoA's explanation but on some aircraft there's a system reason as well. On a lot of aircraft, the Auxiliary AC Busses are dropped at the same time as the electrical Hydraulic & Fuel Pumps are switched on automatically as the Flaps deploy (typically > 3 degrees). to avoid overloading the Generators. Lighting is a large percentage of total electrical load and the "mood" lights (upwash & downwash) are often on the Auxiliary Busses hence they're dropped automatically as the aircraft is set up in takeoff configuration (and landing of course).
In cruise (Flaps 0), all electrical pumps are switched off (the Engine Driven Pumps and motor flow Injectors do the job) and the Auxiliary loads (lighting, Galley Power etc) come back on line.
In cruise (Flaps 0), all electrical pumps are switched off (the Engine Driven Pumps and motor flow Injectors do the job) and the Auxiliary loads (lighting, Galley Power etc) come back on line.
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This topic has been covered several times before, smoothpilot. Here's one of the message threads relating to this subject:
http://www.pprune.org/forums/showthr...ht=cabin+light
Rgds.
Q.
P.S. I'd be a little concerned if the lights went out automatically on a Boeing 767 or a 747 if the aircraft was simply in takeoff/landing configuration (the 767 does have an engine start electrical loadshedding process, but shouldn't otherwise shed electrical loads unless a generator has failed... or the aircraft is dumping fuel).
http://www.pprune.org/forums/showthr...ht=cabin+light
Rgds.
Q.
P.S. I'd be a little concerned if the lights went out automatically on a Boeing 767 or a 747 if the aircraft was simply in takeoff/landing configuration (the 767 does have an engine start electrical loadshedding process, but shouldn't otherwise shed electrical loads unless a generator has failed... or the aircraft is dumping fuel).
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Flaps One! A fully-credited aircrew member like you and you honestly dont know what the non-blinding Day Savings procedure is and how it helps over aircraft in the area?
Unejamakated Phillistine!
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Getting back to the original question, it also serves for the cabin crews eyes to adjust to the night conditions so theyll be able to see clearley whats happening outside if an evac becomes necessary and determine wether that exit is suitable for use.