Take the 2-minute tour ×
Travel Stack Exchange is a question and answer site for road warriors and seasoned travelers. It's 100% free, no registration required.

When I step into an aircraft lavatory, the light is off and there is an indicator light saying to lock the door. Once I do lock the door, the light turns on, and otherwise, the light remains off. Why is it that I must lock the door in order to turn on the light inside the lavatory?

share|improve this question
3  
Another one in great line of toilet questions... :) –  Karlson Aug 14 at 13:16

1 Answer 1

up vote 35 down vote accepted

Three reasons for this:

The main reason: Passenger comfort. If the light continuously remains on, then if a passenger opens the door of the lavatory when the cabin lights are off, it will fill the cabin with unwanted light. This can be avoided by making sure that the door is closed before turning on the light. Aircraft lavatory doors and door frames are designed to make sure that light coming from inside the lavatory does not reach the passenger cabin and vice versa.

The secondary reason: Energy conservation. By closing the door, though the system is sure that no unwanted light will pass into the cabin, by forcing the passenger to lock the door before turning on the light, the system saves energy by not turning on the light whenever there is no passenger inside. Certain aircraft, but not all, have a little low-energy light to make sure that the passenger can still see inside (and thus be able to see the switch to lock the door) if the door is closed but not locked, but this is immediately switched off the moment the door is opened.

The tertiary reason (obvious): Privacy. The light also acts as an enticement (in case the "Please Lock Door" indicator fails to do so) in order to get the passenger inside to lock the door (because not locking the door will make the lavatory appear vacant to another passenger on the outside).

However, in cases where there are windows in the restrooms (is the case with certain A380s and B787s), sunlight from the outside could potentially enter the cabin when the door is opened. This can be avoided by using an electronic sunshade or by using a Boeing 787-style opacity setting that immediately darkens when the door is unlocked.

UPDATE: The above only appears to be the case on long-haul, wide-body aircraft (I last tested this on a Boeing 777) and not on narrow-body aircraft (the light only slightly brightened when the door, even with the cabin lights fully off, is locked when I tested this on both a Boeing 737-800 and Airbus A320 recently).

share|improve this answer
19  
Believe it or not, there are many people who are unclear on the concept of locking toilet doors in Southeast Asia who also do not have great command of English. This is a great way to help them know to close the door, as the privacy is both-ways (most passengers would prefer not to walk in on someone using the facilities) –  jmac Aug 14 at 2:04
3  
+1 nice answer! in addition to that, it is better for safety to switch off as much lights as possible in the lavatories when there are no people inside, to reduce the chances of electrical fires being started and no one to report it. –  MeNoTalk Aug 14 at 5:31
    
@MeNoTalk By using LED lights, there is a much less risk of electrical fires than with older fluoresecent tubes. But yes, that is another reason (yet not as important as the three main ones I've listed above). –  damryfbfnetsi Aug 14 at 5:33
    
@damryfbfnetsi yes not as important and it is from the old days, but aviation safety works that way, many regulations and policies are there for things that might happen very rarely. Also, one of the first steps to take in electrical fires in planes is to switch all lights off in the aircraft and only turn reading lights on, hence there are always a master switch in all aircrafts to override passengers' settings and to turn on all reading lights. –  MeNoTalk Aug 14 at 5:36
    
@jmac True :) Happend to me on my last flight to India :) –  RoflcoptrException Aug 14 at 7:20

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.