Why do they turn off and on interior cabin lighting during take-off and landing? here is the correct answer...

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Federal Aviation Regulation











Sec. 23.812





Part 23 AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES


Subpart D--Design and Construction Personnel and Cargo Accommodations





Sec. 23.812





[Emergency lighting.]





[When certification to the emergency exit provisions of Sec. 23.807(d)(4) is requested, the following apply:


(a) An emergency lighting system, independent of the main cabin lighting system, must be installed. However, the source of general cabin illumination may be common to both the emergency and main lighting systems if the power supply to the emergency lighting system is independent of the power supply to the main lighting system.


(b) There must be a crew warning light that illuminates in the cockpit when power is on in the airplane and the emergency lighting control device is not armed.


(c) The emergency lights must be operable manually from the flightcrew station and be provided with automatic activation. The cockpit control device must have "on", "off," and "armed" positions so that, when armed in the cockpit, the lights will operate by automatic activation.


(d) There must be a means to safeguard against inadvertent operation of the cockpit control device from the "armed" or "on" positions.


(e) The cockpit control device must have provisions to allow the emergency lighting system to be armed or activated at any time that it may be needed.


(f) When armed, the emergency lighting system must activate and remain lighted when--


(1) The normal electrical power of the airplane is lost; or


(2) The airplane is subjected to an impact that results in a deceleration in excess of 2g and a velocity change in excess of 3.5 feet-per-second, acting along the longitudinal axis of the airplane; or


(3) Any other emergency condition exists where automatic activation of the emergency lighting is necessary to aid with occupant evacuation.


(g) The emergency lighting system must be capable of being turned off and reset by the flightcrew after automatic activation.


(h) The emergency lighting system must provide internal lighting, including--


(1) Illuminated emergency exit marking and locating signs, including those required in Sec. 23.811(b);


(2) Sources of general illumination in the cabin that provide an average illumination of not less than 0.05 foot-candle and an illumination at any point of not less than 0.01 foot-candle when measured along the center line of the main passenger aisle(s) and at the seat armrest height; and


(3) Floor proximity emergency escape path marking that provides emergency evacuation guidance for the airplane occupants when all sources of illumination more than 4 feet above the cabin aisle floor are totally obscured.


(i) The energy supply to each emergency lighting unit must provide the required level of illumination for at least 10 minutes at the critical ambient conditions after activation of the emergency lighting system.


(j) If rechargeable batteries are used as the energy supply for the emergency lighting system, they may be recharged from the main electrical power system of the airplane provided the charging circuit is designed to preclude inadvertent battery discharge into the charging circuit faults. If the emergency lighting system does not include a charging circuit, battery condition monitors are required.


(k) Components of the emergency lighting system, including batteries, wiring, relays, lamps, and switches, must be capable of normal operation after being subjected to the inertia forces resulting from the ultimate load factors prescribed in Sec. 23.561(b)(2).


(l) The emergency lighting system must be designed so that after any single transverse vertical separation of the fuselage during a crash landing:


(1) At least 75 percent of all electrically illuminated emergency lights required by this section remain operative; and


(2) Each electrically illuminated exit sign required by Sec. 23.811(b) and (c) remains operative, except those that are directly damaged by the fuselage separation.]





Amdt. 23-46, Eff. 06/16/94





Comments








Document History


Notice of Proposed Rulemaking Actions:


Notice of Proposed Rulemaking. Notice No. 90-20; Issued on 08/23/90.





Final Rule Actions:


Final Rule. Docket No. 26324; Issued on 05/11/94.











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Why do they turn off and on interior cabin lighting during take-off and landing? here is the correct answer...
MMMM....sounds like you answered your own question. Why?
Reply:The regulation you're citing here deals with EMERGENCY lighting - not the same thing as the normal interior lighting.





(The emergency lighting includes the floor "track lighting", the "EXIT" signs, some of the overhead lights, and some of the exterior lights near the exits).





By the way, electrical power is not generated by hydraulic pumps (as another person suggested). There are engine driven alternators and generators as well as inverters and rectifiers to supply electrical power. Hydraulic pumps supply hydraulic pressure to operate things such as (this is aircraft dependent - they aren't all the same) brakes, landing gear, flight controls, flaps, and nosewheel steering.
Reply:you answered your own question dude.....and btw about 90% of todays fleet of commercial aircraft power their electrical systems by using hydraulic pumps.
Reply:Uh, no.





What that says is that there must be a system BESIDES the main cabin lighting that will illuminate during an emergency.





In the case of Boeing and Airbus aircraft, these systems are battery powered, or in some cases, they use safe-t-glo strips that have to be maintained by checking them for luminescence.





So, while you got the right info from the FAA website, this does not say that the main cabin illumination must be turned off during take-off and landing, it simply describes the system that must be in place and operable in an emergency on any aircraft used as a transport aircraft.





Drumgod - What are you talking about?


The electrical system is driven by generators on the engines and, when switched on, the APU. When on the ground, it's either the APU (when the engines are off), or ground power.


Hydraulic pumps provide HYDRAULIC power.
Reply:Thank you!





Now perhaps you can tell them once and for all why airplanes aren't made out the same stuff as those dad-blasted black boxes that are actually painted orange and while you're at it tell them why passengers on airliners don't get parachutes.
Reply:ummm, thanks...





and your question IS?
Reply:Excellent, but the section of FAR's that you quote is talking about requiring aircraft to have emergency lighting systems... not why the cabin lights must be turned off...





Please, someone tell me what I missed when I read through this...





It simply says that airplanes must be equipped with an emergency lighting system that... ect. ect. ect.
Reply:That's what I said the first time this question was asked.
Reply:No. Here is the correct answer: Some people barf on takeoff and landing and it would be embarrassing for them to be seen. I certainly don't want to see it, hear it, or smell it. So, lights out everybody!
Reply:FOR EMERGENCY CONDITIONS