Boeing's Connexion announcement

Mon Oct 16 01:40:06 UTC 2006

On Oct 15, 2006, at 8:21 PM, John Levine wrote:

>
>>> In addition to all of the offered AC services others have mentioned,
>>> some planes have power outlets for vacuum cleaners, typically  
>>> behind a
>>> small panel next to a door.
>>
>> ISTR, these AC sockets are "airplane flavour" 115VAC @ 400Hz.
>
> No. it's 60 Hz.  See this picture of one of the outlets.
>
> http://www.flickr.com/photos/joi/25645286/
>
> and this page from Qantas web site
>
> http://www.qantas.com.au/info/flying/inTheAir/communications
>
> Don't you think that airlines would be smart enough not to install
> power outlets that would destroy the equipment that the customers plug
> into them?
>

There are two different things that are being talked about here. If  
your seat has an obviously-meant-for-customer-use outlet, it's  
definitely going to be 60Hz.

There are other outlets that look like regular North American  
outlets, but hidden behind an access panel. Usually on the floor or  
near a door, with no markings on the outside as to what they're for.  
These *are* 400Hz, and are meant for support crew to clean the  
aircraft with, maintenance tools, etc.

I just asked a flight attendant friend of mine about them, and she  
says they're present on many of the aircraft she's worked on.  
Initially the flight crew would look the other way when a traveller  
would plug their laptop in, but with a "that might fry your laptop"  
warning if they were feeling especially generous. Not too long ago  
though, they were instructed to aggressively stop people from using  
the outlets. Partially out of fear that someone's power supply/ 
battery would fail in some spectacular way at 30,000 feet, and  
partially because they have a lesser known secondary use.

While she's never seen any of it in use, there are medical devices  
designed to be able to use these outlets in an emergency or for a  
critically ill patient being transported. They're specially designed  
to accept 400Hz power, and draw more power than the seat provided  
passenger outlets. If you somehow popped the breaker for the 400Hz  
maintenance outlet, several bad things happen... They're required to  
reset the breaker, which is located in a very inconvenient place. Not  
only can they not take off if the alarm showing that this breaker is  
tripped is active, but there's some very slight chance that you've  
just broken the power feed that might be needed in an emergency.

She says she's only heard of one person breaking their laptop (or  
power supply, she wasn't sure) from trying to use one of those  
outlets with dozens more cases of seeing people using them without  
problem, but at least on her airline she's not allowed to look the  
other way if she sees anyone trying to use them anymore. She recalls  
at least one fight where they were delayed at the gate waiting for  
someone to go reset the breaker under the cabin floor to restore  
power to it, even though they had nobody onboard with a device that  
was supposed to be used in it.