Airplanes: Why the silly double headphone jack?
February 20, 2010 12:27 AM   Subscribe

AirplaneFilter: Why do airplanes have such weird headphone jacks (power jacks, too, while we're at it)? What's the benefit of having the double-jack except to require the use of crappy airline headphones or an adapter?
posted by sdis to Technology (14 answers total) 1 user marked this as a favorite
 
You have to buy the adapter. That's the reason.
posted by sanka at 12:29 AM on February 20, 2010 [1 favorite]


So you don't steal the headphones.
posted by pompomtom at 12:31 AM on February 20, 2010 [3 favorites]


Either so you don't steal the headphones, so they can sell the headphone usage to you, or sell the adaptor.

It's all about money.
posted by Brockles at 12:40 AM on February 20, 2010 [1 favorite]


The power jack makes sense, it's more efficient to provide a 14 VDC thing when your power supply is DC instead of inverting up to 110VAC, just for the devices people bring on planes (phones, laptops) to convert back down to low voltage DC.

The headphone thing is fucking nuts though.
posted by floam at 12:41 AM on February 20, 2010


The double-jack system is (presumably?) a remnant of the old air tube-style headphones of days long past. Back in the day, you could roll up a piece of stiff paper in the shape of a cone, jam it in the headphone jack, and have a makeshift speaker playing the in-flight music for you and your seatmate. Backward compatability, as usual, ruins everything.
posted by 0xFCAF at 12:47 AM on February 20, 2010 [5 favorites]


Some airplanes have a single jack. I was on an A330 just the other day, and no second jack in sight. I think the twin jack is just an old thing.
posted by Sova at 12:53 AM on February 20, 2010


Air tube. When I was 9 and flying to the US, I remember falling asleep on a TWA flight and putting my pillow up against the ports.

Later, when audio became less retarded, everything went to electric and now you have a dual-prong system for no reason other than rentals/adapter sales in some planes, while with others you have a stereo plug for your iPhone headphones. Or, like with budget carriers, you get nothing.

The bigger question: why don't light aircraft just standardize on a single format U-92 plug like in rotorcraft, or the other way around?
posted by electronslave at 1:22 AM on February 20, 2010


An airline I was on recently had the double jacks, but you could bend move one out of the way for normal use and you were encouraged to take them home. Headphones are now very cheap, but it takes a long time for things that work OK to change in the airline industry.

I used to love the old air tube headphones: squeeze for do it yourself wah-wah.
posted by hawthorne at 5:16 AM on February 20, 2010


In the last five years I've been on a northwest plane that still had the mechanical earphone tube thing and a jetBlue flight that had a proper headphone jack. I suspect it's one of those things that never gets upgraded once a plane is put into service.
posted by modernserf at 6:19 AM on February 20, 2010


I was once told by a long-time airliner maintenance guy that the dual-prong electrical plug is a holdover from when personal headphones weren't all that common, and the airline wanted to make sure you returned their rentals instead of taking them home for yourself. This would have been when manufacturing a set of headphones didn't yet cost 12 cents in China, but were actually a significant investment by the airlines.
posted by pupdog at 8:22 AM on February 20, 2010


I was just on a United 767 with the double jacks and discovered the top one works as a regular stereo jack if you plug regular headphones into it. I always assumed, as mentioned above, that the double jack was there so you didn't steal the double-jack headphones.
posted by rtimmel at 9:09 AM on February 20, 2010


Yes, I think one is a dummy and maybe always was
posted by A189Nut at 11:58 AM on February 20, 2010


The power jack makes since, it's more efficient to provide a 14 VDC thing when your power supply is DC instead of inverting up to 110VAC

Eh? Every large aircraft I know of provides 28 VDC, not 14. And that's just from the batteries; the engines have generators attached to power takeoffs that (usually) provide 110 VAC at 400 Hz.

Anyway, my point being is that VDC and VAC power systems in tandem on an aircraft are very common. Sometimes you can see circular four-prong plugs for the AC system because you can get three-phase power out of the engines, but those are not for passenger use.
posted by backseatpilot at 12:40 PM on February 20, 2010


Eh? Every large aircraft I know of provides 28 VDC, not 14.

EmPower ports, which are the most popular in the US, are 14 VDC.

Oh, and actually reading that page, it turns out I was wrong and it's 15V not 14V.
posted by floam at 12:43 AM on February 21, 2010


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