Why are interior cabin lights turned on/off during takeoff/landing?

here is the correct answer............





Federal Aviation AdministrationRGL Home








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 are interior cabin lights turned on/off during takeoff/landing?
I am just glad they do cause I like to see outside at night during takeoff and landing
Reply:The lights are turned on while taxiing in order to "Charge" the glow in the dark emergency floor lighting. They have to have it on for a certain amount of time to do this. Report It

Reply:This dictates the requirements for emergency lighting which is different from the normal interior lights.





Granted, I don't have a clue why they do it. I sit up front and it makes no difference to me either way.
Reply:I would answer in two ways. The first reason is the exhasuted response from everyone that your eyes need time to reset when the lights go off. (emergency landing) Secondly, I would say that any aircraft needs full power to land and take off. The cabin lights on an aircraft use up some of this power. Switching them off or dimming them, allows more power available to the engines.
Reply:This has NOTHING to do with why the cabin lights are turned off...





You quote a section from FAR's that says, in short, "Airplanes must have an emergency lighting system" and it goes on to explain what this emergency lighting system must be able to do...





Please, if I missed something, let me know, via e-mail or whatever... but the fact is that it does not say anywhere in this quote that the cabin lights must be turned off for landing... it does say that the emergency lighting can work WITH the cabin lights ( first paragraph: SECTION a)... this seems to discredit your entire arguement here...
Reply:Interior lighting are dimmed...


So that in case of an Emergency Evacuation your eyes will stay focused and will be easier to transition to the outside... basically a safety precaution





When I fly... I alwys have my shade open for the same reason
Reply:I'm not saying that this is THE reason, but definatlely one is so that sparks are more readily seen outside during the take off and landing (the most dangerous phases in flight).





Also, I guess in an emergency it would be easier to see the emergency lighting?

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