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Yesterday, I flew on Germanwings 4U2379 with an Airbus A319. The plane's interior looked pretty modern, and while I can't find a construction year online, I'm pretty sure it was built way after the total smoking ban.

This plane still had illuminated non-smoking signs though and I was wondering if the crew would actually be able to turn these off during flight if they wanted to. Is there any information about that?

This question shows that some planes do not even have a non-smoking sign anymore, but it does not elaborate on the mechanics of existing signs.

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  • $\begingroup$ Related. $\endgroup$ – mins Jun 30 '15 at 9:16
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    $\begingroup$ There is no such thing like "the total smoking ban" as it's still up to the airline / its country if smoking is allowed or not. May be, the illuminated sign is still there to permanently point the passengers to the fact that it's not allowed. (They also don't stop to say that it's prohibited on the toilet, too, and that the toilet has smoke detectors...) $\endgroup$ – sweber Jun 30 '15 at 9:26
  • $\begingroup$ I get why it is still there. But Germanwings has no flights where smoking is allowed and my questions was whether they could still turn it off or if that was prevented by design. $\endgroup$ – helm Jun 30 '15 at 9:29
  • $\begingroup$ At least here in the U.S. (where smoking on board has been illegal for quite a while,) a lot of the planes now just have permanent placards in lieu of the lighted no smoking signs. $\endgroup$ – reirab Jun 30 '15 at 14:43
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    $\begingroup$ Keeping the sign operational makes it easier to sell the plane in a few years to an airline where smoking is still allowed. $\endgroup$ – Peter Kämpf Jun 30 '15 at 22:14
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It would appear that the aircraft you flew was D-AGWR, a A319 with MSN (Manufacturer Serial Number) 4285 delivered in April 2010 (hence fairly new).


There is a switch at the bottom of the overhead panel, next to the seat belt sign, slightly right of the middle. Flip it and they will extinguish. The functionality is a bit more complicated than it would appear, since it feeds into the central aircraft electronics.

enter image description here

Olivier Cleynen at Wikicommons

Out of interest, this button no longer exists on the Boeing B787, suggesting that it is on the way out. Only the seat belt option remains.

The slots for no smoking are being increasingly 'redeveloped' into a sign for electronic devices instead on some types. They just put a no smoking sticker on the seat in front of you to fulfil the same function. I do not know if they cockpit text has been modified on the aircraft that undergo this modification.

pic

Source

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  • $\begingroup$ How did you go from flight number to aircraft serial number? $\endgroup$ – cpast Jun 30 '15 at 13:03
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    $\begingroup$ @cpast planefinder.net/data/flight/4U2379 and then via registration to serial number through planespotters.net. $\endgroup$ – Thunderstrike Jun 30 '15 at 13:10
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    $\begingroup$ @MikeFoxtrot Thanks for pointing out that link! It might be a good idea to even post cpast's question and (perhaps a slightly expanded version of) your answer as a separate question, since it's rather useful information and that would make it searchable. $\endgroup$ – reirab Jun 30 '15 at 14:20
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    $\begingroup$ @reirab good idea -- posted. I'll let MikeFoxtrot post his answer, as he'll be better able to expand on it than I would. $\endgroup$ – Ralph J Jun 30 '15 at 15:34
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    $\begingroup$ What's sad about this, is that the "turn off electronic devices" is already out of date, because now we're always allowed personal electronic devices (though there are times when we can't use laptops) $\endgroup$ – McKay Jun 30 '15 at 19:28
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In extremis, every electrical item on a plane can be switched off, to protect the plane if the item malfunctions. For example, a short-circuit in the no smoking signs could, in principle, cause a fire. At the very least, there will be a circuit breaker that can be removed to remove power from the signs. However, I don't know if there would be an individual breaker for that system: there might be a single breaker that isolates several related systems.

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  • $\begingroup$ I was just going to say this myself. Good answer. $\endgroup$ – KeithS Jun 30 '15 at 16:35
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    $\begingroup$ Or it could cause an odor, which isn't a good sign either. $\endgroup$ – fooot Jul 1 '15 at 14:25
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In the Airbus A320s I have piloted, no you cannot turn the no smoking signs off even if you put the switch to off position. I am pretty sure, back in the day when smoking was allowed you could do it and there maybe some older MSNs that allows the pilots to switch off the no smoking signs. In later models it is always on. I am not sure what exactly is a later model. I have flown A320s built as early as 2005 and the no smoking cannot be turned off in them.

The reason why there is an off position in the no smoking switch is because in Airbus aircraft it performs some other function as well and that is, it controls the aircraft emergency EXIT lights. You can see these lights in the aircraft ceiling and main entrance and emergency exit doors. From an operational point of view, during cockpit preparation we put the no smoking switch to auto position. When in auto position, with landing gear extended the emergency exit lights come on. Once the landing gear is retracted after take off, the exit lights go off. Anyone who has flown an Airbus would have most probably heard a 'bing' right after take off. This is the chime that comes on when the exit lights are turned off. When you are coming in for landing and when the landing gear is extended again the exit lights are turned on and the distinct 'bing' is heard.

enter image description here

An A320 EXIT light.

Once the flight is done with we do an aircraft securing checklist and this involves turning off the no smoking switch. One might wonder why we do that even though it does not turn off the no smoking signs. The thing is, if the switch is kept in auto or on, the exit lights remains on as long as the aircraft is powered. This prevents the internal emergency light battery packs from charging, because with the lights on, the charging is automatically inhibited. The last thing you want is a drained battery pack in an emergency evacuation. Now, that would not be fun, would it? Panicking passengers in a totally dark aircraft!

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One option, used by at least some airlines, is that while the lighted "no smoking" signs have been replaced by placards (no lightbulbs to ever need replacing), the cockpit switch itself still works in that it produces a single tone chime when turned on or off. Since this chime is audibly distinct from the usual high-low F/A Call chime, it could be used as a method of notifying the cabin crew (although I don't know if or how often it's actually employed that way).

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