Show HN: Hacking airplane headphones | Hacker News Reader

Show HN: Hacking airplane headphones

ttboj.wordpress.com

146 pointspurpleidea107 comments

He was lucky that the headphones used standard rubber insulation. It's common for headphones to use bare copper wire coated with some sort of insulating lacquer, that can't be stripped mechanically.

The best way I've found to remove such insulation is to light it on fire, which would be frowned upon during a flight.

That's "enameled wire", also known as "magnet wire".

You can sand the insulation off with an emery board, commonly found in nail care kits.

You can also scrape it off with a blade. Just don't use one you care about, because the metal dulls blades quickly.

There's an old trick there (not for use on commercial flights...), if you place the enamelled copper on an asprim tablet and briefly touch them with a soldering iron, it almost magically becomes clean solderable shiny copper.

(Source: I rewound _so_ many CD Rom drive motors into model airplane motors back before you could buy them easily... I think my knowledge of that asprin trick predates that by a decade or more though...)

THANK YOU

So many headphones to fix. So many Litz-wire inductor cores in Class-D amplifiers to solder. Thanks.

Off-Topic: any chance you've got some literature on the subject of turning CDROM drive motors into model airplane motors? This sounds like a great hack for HN ..

I am wondering if he is this guy:

http://www.flyelectric.ukgateway.net/cdrom.htm

That's not me, but that's pretty much exactly the process... It was pretty common maybe 10 years back - these days there's a huge range of purpose-build brushless motors available from places like HobbyKing.com for such small amounts of money that I suspect _nobody_ of spending all that time to make their own (at least not in the "saving a few bucks for my hobby" class, I think the top end competition guys are probably hand making motors still...)

Wow, that's a trick worth knowing. I've tried everything, but this sounds promising.

The aspirin trick works wonders. However, the resulting smoke doesn't smell like roses. Just remember not to breathe it :)

Heh, reminded me immediately of the will it blend guy.

"Asprin smoke, don't breath this!"

Man, I was thinking that would be such a pain to use because whenever I hack something together like that it's super sensitive to jostling, but tying it off like that is just brilliant! I'm going to use that.

Also:

> The finished product worked beautifully, despite now only providing monaural audio and is about five centimetres shorter, which is still perfectly usable since the seats hardly recline.

I would consider the monoaural audio to be a benefit! When possible, I try to set my phone to force mono. I'm considerably more likely to be distracted by stereo effects than entertained by them.

I feel that stereo makes for more spacious sound. The sound feels like it is filling the room, whereas mono feels kind of claustrophobic.

Glad you liked the hack! With some bad stereo signals, I've found the audio dialog to be softer in one of the two channels, and the music in the other, so if you're watching that sort of film you might not get the best mix!

Maybe I'm missing something, but couldn't you just buy the proper adapter for $1.60?

http://amzn.com/B00G53TDF4

It's a long shot, but you might be missing that he was on an airplane?

Or that he specifically says the Left (or was it right? ;)) headphone socket, built into the seat, was broken.

Amazon drone delivery?

You can also just use normal headphones, but not push them in all the way into the socket. You'll only get mono (through both speakers, but only a single channel), but if you don't have an adapter it works and your headphones are probably a lot better than what's on the aircraft.

The third pin is to provide power for active-noise cancellation headphones. Most airlines usually only give them out in business and above now.

Why does this work exactly?

I did this once on a flight by accident using Apple earbuds then confused myself when I couldn't replicate it. Thanks for the tip.

I've always wondered why they don't just supply these on the plane. One adapter would last much longer than one pair of shitty airplane headphones that most people toss after the flight anyway.

I'm really saddened by the first thought that came to my mind: "I could have never pulled this off because of my skin color"

don't worry, my first thought without that was, "holy shit what kind of an idiot is doing this on a plane". skin color doesn't matter, that is not normal in-plane behavior.

Or, just stick a regular 3.5mm headphone jack into the two-pronged hole half-way in. The contacts line up in such a way that one channel touch both inputs. Just turn up the volume a bit.

I always have one of these two-pin-to-3.5 adapters in my bag when I fly:

http://www.ebay.com/itm/2-pcs-3-5mm-Airline-Airplane-Earphon...

I recommend also adding this to the flying set: https://www.amazon.com/Stellar-Labs-35-4180-Headphone-Contro...

In most airlines the announcements are at fixed volume, independent of the movies. That means you can put the video on full volume and turn it down inline. No more announcements screaming in your ear :) (and better sound quality as a bonus)

Both your link, and the link above, are two components I recently purchased after my own experiences. Just funny to realise I wasn't the only one who encountered this...

Yes, I too travel with both of these. The volume control is convenient, but I originally bought it after breaking a couple of my headphone connectors. Now I break a $5 part instead of a $50 part. (Shure's with removeable cords are great, but the cord is still $50)

You know what I would pay for? Some sort of holder or cradle that would hold my laptop at an eye level.

I actually tried this initially, but unfortunately it did not work. And this way you got a (cool?) article out of it.

Love it.

The part that was omitted:

"Hey, do you have some tweezers I can borrow?" "Tweezers? Um, no. I have an extra pair of headphones, though. It looks like you're having trouble with yours." "Oh, uh, no thanks--I just need some tweezers."

The reason this is so cool is because it's a perfect example of problem solving, and how our determination kicks in when we have an innovative solution. Even if that means skipping over the easiest or the most common solution.

Hehe, ironic response about missing the obvious, since the first thing the hacker did was check it wasn't the headphones that were faulty :-)

Asking a co-passenger for a spare set of phones would have left him with the same problem: the plane socket was only feeding audio from one hole, not both.

Nice. I wonder if he's a climber?

https://en.wikipedia.org/wiki/Figure-eight_loop is a classic climbing knot and I guess most people would just use an overhand knot.

I usually prefer a bowline for tying in, but that's not as safe. :)

looks more like an overhand loop to me https://en.m.wikipedia.org/wiki/Overhand_loop

Definitely figure eight. He says as much in the article.

I used to climb, yes, and I've learned a lot of knots. I used a figure-eight for one of the reasons it's used in climbing: the bend radius isn't as sharp, thus putting less strain on the knot.

Anyone know anything about those USB connectors? I was on a flight some time ago and noticed that my device said that USB debugging is now connected (Android), when I plugged it in, so I don't think it was only for charging. Don't remember which airline it was.

I remember at least one system where the USB port allowed you to plug in USB stick and then let you listen to the music you had on it. So it's just a proper USB host.

I don't plug my USB devices into strange USB ports (because I don't own a USB condom):

See: http://krebsonsecurity.com/2011/08/beware-of-juice-jacking/

iOS 7 onwards (AFAIK) doesn't allow a data connection by default: https://support.apple.com/en-us/HT202778

Not needed since android will ask you to verify PC fingerprint before exchanging any data or allowing debugging.

I guess it's a case of defense in depth. Software may have vulnerabilities that still allow for data connections despite the prompt. But no data wires being physically present cannot have that problem at all.

There are "charging only cables" available that basically do the same stuff: They have the data-pins bridged in some strange way to persuade the phone and charger to consume/provide maximum charge current.

e.g. https://www.amazon.de/gp/product/B00JL1490G

No data transfer possible, and the particular cable linked feels as if it would have an adequate copper cross-section for the 2½A it's rated at.

Be careful with those --- the cable is lying to the phone about whether the thing you've plugged it into is a fast charger or not, so if it's not, you can end up drawing way more current than it's rated for.

A well designed USB charger will just shut down if this happens. A non well designed USB charger is another matter.

You get to choose connection mode when you connect to any computer. The entertainment system tries to connect to your media storage so that you can play your own music/videos. (this system is often just a Linux terminal) You can always use the charging-only USB cable if you're worried about the data connection of course.

Mine seems to say that anytime you connect it to any computer, even if that computer doesn't even have ADB installed, much less running. Probably a subtle defense-in-depth encouragement to leave debug off when you aren't actually intending to use ADB.

I wonder if it's left in from before they had the PC fingerprint check, and nobody ever bothered to take it out.

I carry an adapter for these connectors in my Bose headphones case:

https://www.amazon.com/Golden-Plated-Airline-Airplane-Adapte...

This is also a great way to get arrested thanks to some overly concerned seating neighbour.

I'm surprised that someone actually managed to smuggle tweezers onboard!

Tweezers are not prohibited (by TSA) on carry-on bags

You're implying TSA employees are trained properly. I've had to surrender small items that are not prohibited due to incorrect assumptions that airport security have made.

I had a grooming kit with a pouch containing assortment of small things like nail clippers, tweezers, and tiny safety scissors that I carried with me on every flight. Gradually, the pouch became completely empty as TSA agents confiscated more and more of my items.

Yup, shortly after 9/11 I flew to Hong Kong and I forgot that I had my mini screwdriver kit (small screwdrivers for electronics, smaller than my pinky finger) in my bag. It got confiscated, to my disbelief.

Yes, HK searched my mini screwdrivers, and the security guy checked the size of the ends against his pinky finger, and since they were the same size, he let them slide.

Your parentheses make a good point: we don't know why if the OP was flying from/to the US at all. Other countries have different regulations. I've been allowed to carry a Swiss Army Knife onto a European flight because neither of its two blades was longer than 6 cm. (I've also had a bread knife confiscated because its blade was longer.)

I was thinking the EXACT same thing, especially considering the UPenn professor who was reported for writing mathematics on the plane.

So you're thinking something like this?

Author: <fiddles with headphone jack>

Author: <fiddles with headphone jack some more>

Author: "Hey, can I borrow some tweezers? I think this headphone jack is busted and I want to adjust these headphones so they'll work."

Seat Passenger: "No problem."

Author: <starts stripping the wires from his headphones>

Seat Passenger (thinking): "Stay cool, Phillip, this guy is clearly a terrorist..."

Author: <plugs in headphones>

Author: "Hey, it works! Thanks, bud!"

Seat Passenger (thinking): "Where is that god damned air marshall. Oh god, what am I going to do?!"

Never underestimate the depths of people's stupidity.

https://www.washingtonpost.com/news/rampage/wp/2016/05/07/iv...

^ It's amusing watching the upvotes and downvotes on this comment oscillate sinusoidally centered around 7.

Given that a man was taken off a flight for doing Algebra, I set a low bar for how paranoid some passengers are.

Depends what colour you are really.

That's cool. Reminds me of being a kid in the 70s and switching though the channels on a 747 flight - one channel was playing all music backwards, and finally recognized one as Dolly Parton's 'Jolene' https://www.youtube.com/watch?v=b9re90HG2dw

This is a good opportunity to post the surprisingly good slowed-down version of _Jolene_.

https://youtube.com/watch?v=CMrfM711vXI

Try this as a Muslin and you are (probably) dead...

Actually, try this as a non-white person and you are dead...

Actually, try this, and you are dead (not sure how the author got away with it).

Once I was flying to the United States and in the middle of the flight the screen in front of me printed a familiar image, Tux, the famous penguin icon of Linux (the entertainment system was rebooting or something). I thought it was interesting so I decided to take a picture, the woman that was sitting on my side asked me what was that and why was I taking a picture, so I smiled and said "Somebody hacked the plane", as you can guess she didn't get the "joke" and started (nervously) to look for one of the flight attendants, 3-5 minutes later she went to the bathroom but oh surprise (or maybe not) she returned with two of the flight attendants that started asking for my passport and to allow them to check my cabin bags. They were cool after I clarified the situation, but this was a lesson for me to 1) don't try to do stupid things in a plane, 2) don't joke with nervous people.

I just remember the story of this mathematician that was writing some formulas in the plane and the person on his side thought that he was planning a terrorist attack. This is why it surprises me that the author of this article was able to get away with his "experiment" just like that.

EDIT: Re-reading the article, he says that "the flight staff weren’t angry that I had cannibalized their headphones" and then continues with "If you work for Emirates, let me know and I’ll give you the seat and flight number". Considering this I will assume that they weren't angry because a) its a rich airline so they assume that people taking their flights are "harmless", or b) Middle East citizens are used to plane hijacks (this is actually a really bad joke, and I will accept the downvotes with resignation).

> its a rich airline so they assume that people taking their flights are "harmless"

It's your average airline that spans from Europe to Australia from bases in middle east. Nothing really rich about it. (although, it is quite comfortable)

Emirates has some of the highest revenue and cost numbers per average seat kilometre [0]. It's also subsidised to a large extent by the UAE [1]. I don't find the word "rich" to be very descriptive, but "high end" could easily apply in this circumstance.

[0]: http://www.oliverwyman.com/content/dam/oliver-wyman/global/e... [1]: http://www.prnewswire.com/news-releases/emirates-confirms-bi...

I don't necessarily disagree with the high end. But looking at the CASK it's worth noting that they're almost exclusively long-distance flights. I'd like to see the graph from [0] split into long-haul and others. Currently they've got Emirates flying 10+ hours on the same graph as EasyJet doing 30min in Europe. Same for Quantas which does domestic 1h flights as well as international Dubai, or west coast US but is in one bar only. I know these are normalised per kilometer in theory, but there's a threshold when you need 2x the crew, can't really go without entertainment system, etc.

Or specifically why I didn't say rich is that it's not like you have a lot of choice flying long-haul over middle east. You're likely to get a stop-over in Dubai and if you're flying One World, you're likely to have an Emirates code share.

Of the ME3 Qatar is the one that's in oneworld. Though it is Emirates who usually codeshares with Qantas because of their separate partnership agreement.

You're right. I got so used to flying Emirates/Qantas codeshares I was sure it's because of One World. You learn every day...

Where does virgin stand? I thought they are the most expensive.

Also I didn't find Emirates particularly different. The ones that did stand out to me is SAS.

There are a few different Virgin Airlines atm (Australia, Atlantic, e.g.)

Despite the media amplification and muckraking, and general 'agitprop', millions of Muslims fly every day without being murdered by other passengers or flight crews.

They are horribly profiled in security, but again, claiming they will be murdered is a bit of an exaggeration.

I think it is a sad commentary on our society that all comments so far revolve around the possibility of being arrested for this simple hack :{

it's not sad, it's cautionary. It's impressive to me, but it's also incredibly difficult to keep hacking and doing cool stuff from inside prison.

I think HN should bare some if not all of that comment.

People didn't have to comment this way, but they chose to.

Society are not idiots. No people would not report you for doing this, no more than people might murder you. Yes it could happen but it won't.

I'm sad that anyone thinks this is hacking

Why be sad? Define a "hack". I think this fits the bill, maybe you're thinking of "cracking" ? :)

No, I'm not. It's just totally lame, like "how I changed a US for a UK plug" or something

Makes note never to fly Emirates internationally incase I get stuck with these anti-customer audio jacks.

I think that's a bad decision on N=1 samples. I find international Emirates flights to be one of the most modern and comfortable ones. I mean, you even get power sockets in economy most of the time, which is still pretty rare.

Connectors like these are pretty much a standard for whatever crazy reason as well. (the third hole seems to provide some power, since their noise-cancelling version in business uses it)

I've seen similar jacks on multiple airlines.

It's not the airline, it's the aeroplane manufacturer. Boeing and Airbus use different connectors.

...which are still there only to make you pay for proprietary headphones.

Pay for headphones? What airline is that? I've flown on a lot and I've never had to pay for them.

I've always assumed they used the weird connectors to prevent people from taking the headphones with them (since they can't easily be connected to anything except an airline entertainment system)

Some do. I think in the US it's somewhat common for many domestic flights still. It used to be way more common.

http://www.flyertalk.com/forum/travelbuzz/862199-does-any-ai... http://www.fodors.com/community/air-travel/headsets-on-delta...

I've heard that also historically one of the big reasons for the odd jack was to prevent theft (back when headphones were relatively more expensive and all airline headphones were designed for reuse...)

Emirates gives you headphones for free (standard in economy, noise-cancelling in business), it's not like they make money on this. I don't think Boeing and Airbus care about the headphone sales either.

Neither Boeing or Airbus specify trivia such as headphone connectors. They provide their airline customers with a list of seat options from approved suppliers and the airline chooses based on their criteria.

A company local to me, Thompson, manufactures seats and competes for customers through both big OEMs.

http://www.thompsonaero.com/

You're probably right - I just noticed they were different on say, Air Canada vs Qantas and assumed the aircraft type was the differentiation. If I was travelling again I'd just buy adaptors from AliBaba.

I've yet to buy a set of noise-cancelling headphones that didn't come with an adapter for these, which seems like a better option. You'll have a hard time finding airlines that use a standard 3.5mm jack.

Emirates Business class gives you a really nice pair of noise-cancelling headphones instead. Not that that is much of a work-around.

Wait. You insulated some live DC wires with _paper_ and then hid that behind some plastic in an airplane somewhere? I'm way more concerned with the fire hazard you introduced than the profiling stuff others are mentioning.

Please don't do this to my airplane.

It's headphones, not some wire hidden behind anything, or anything carrying a significant current. He stripped the wires on the headphones they gave him to listen to the in-flight audio.

Do you have any resources to show how this is potentially a fire hazard? Genuinely curious.. because I often hear people talk about even the most basic electronics as this Big Scary Thing, and in my mind, it is quite simple and harmless.

Please share.

Easy: Because the wires are wrapped in paper, if you simply light a lighter next to them and hold it to the paper for a few seconds, you have kindling. Then, if you can find something in a plane that's not fire-retardant and heat it with the flaming piece of paper enough, voila: an inadvertent fire.

Why go to the complicated step of insulating a wire with the paper? You could make the situation much easier by just tearing some paper out of your notebook for kindling.

Not sure how one would manage to sneak a lighter onboard though.

> Not sure how one would manage to sneak a lighter onboard though.

Lighters are allowed as carry-on luggage: https://www.faa.gov/about/office_org/headquarters_offices/as...

I was being facetious.

And I was laughing. :-) Good one.

Or you could just find something not fire-retardant and apply the lighter to it directly.

Just ask Fire Marshal Bill.

Grandparent misunderstood the post as talking about taking the armrest apart, not the headphones. Nothing to see here.

Max voltage there will be about 2V DC. (Could be up to 3.4V, but much more likely to be 1.73V).

Dry paper is roughly as conductive as glass: that is, no fire is going to happen here. You can't get a spark.

The voltage is less important than the amperage with something like this, but that fact only further emphasizes your point, there's literally zero risk of the paper catching fire.

1.73Vrms / 45 ohms of impedance of headphones = 0.038 mA (doesn't include minor impedance from output)

Power (Watts) = V^2/R, or I^2*R, so a maximum of 0.067 Watts to start a fire. Not much at all.

Yup, exactly. A static electricity spark is typically high voltage, but very low amperage, and even it would be highly unlikely to set paper ablaze. A headphone is both very low amperage and low voltage, so essentially impossible without an external catalyst.

I would be absolutely floored if this headphone amp had enough current capacity to even noticeably heat up under a dead short.

Reply on news.ycombinator.com