Comment by cmsimike | Hacker News Reader

Comment by cmsimike | Hacker News Reader

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> but it drives me absolutely insane that flight attendants gripe at me about turning off my Kindle

I agree BUT you've got to remember that there are a ton of different devices in the world. You can't expect every flight attendant to know what the difference (visually) is between an iPhone and an iPod Touch is, let alone how to set every device to their equivalent "airplane mode."

Of all the rules I disagree with, this is the one that I understand the most.

> If they were actually that dangerous, we wouldn't be allowed to carry them on board.

My understanding (from a pilot friend of mine) that it is really about radio interference with the pilots' radios. Recall the older Edge (for ATT, whatever else for other providers) devices being put up near speakers and that sound made[0]. The rules are still there mainly to protect the pilots' ears from that noise and possibly dropping communication, though I don't know how possible that is. Yes, that isn't common place anymore now that radio frequencies have moved on but how is a flight attendant going to know the difference between an Edge device that causes interference and some 4G device that doesn't?

[0] http://www.youtube.com/watch?v=R0O1_FYzbjw

Yeah, I feel the same way. If the FCC thinks it's fine, great. Otherwise, I can read a magazine for a few minutes.

The case that I suspect worries them isn't the well-manufactured, brand-new device on a shiny new plane. It's the older, banged-to-hell, third-rate Chinese knockoff against the oldest avionics in service. The question they have to answer isn't, "Should it be fine?" but "Can we prove it will never cause a glitch at the worst possible moment on the most problematic flight of the 10,000,000 we have each year?"

I'm astounded at the arrogance of random people who are sure they know the answer to that based on zero data and a strong sense of entitlement.

If "older, banged-to-hell, third-rate Chinese knockoff against the oldest avionics in service" is, indeed, a threat scenario, then "Things which resemble a Gameboy" would rate at least as high as water on the "Stuff we will not let you take on a plane" list. Al Qaeda can procure old Chinese electronics, or custom-modded Arudinos in casings which resemble iPhones, for that matter.

[Edit for background:

The case against water is "Water is difficult to tell, by cursory visual inspection, from a binary explosive. We've never actually lost a plane to a binary explosive, but we know they were pretty serious about trying that, and we wargamed it out and it looks like one liter of binary explosive applied to the right part of the right airplane means we have a very bad day." ]

I don't think so. The threat scenario that worries me for cheap electronics isn't "flying along in the blue sky and suddenly the plane crashes".

Its "distraction of pilot or minor technical disruption during a difficult landing at a moment that has become crucial because of other issues."

Al Qaeda can't afford to put terrorists with custom electronics on an appreciable fraction of our 10m flights a year hoping they get one of the 10 most vulnerable ones.

But those flights will have hundreds of electronic devices on them. Being 100% sure that there will be zero problems is tricky. And given that the tradeoff is, "people have to read a magazine for a few minutes" versus "fiery death for hundreds", I'm perfectly ok with them being conservative here.

I'm astounded at the arrogance of random people who are sure they know the answer to that based on zero data and a strong sense of entitlement.

I keep getting back to what was already said above: if there was any actual risk whatsoever, we wouldn't be allowed to carry them on in the first place.

That's dumb, just because someone isn't willing to go to an extreme measure to prevent something doesn't mean that more moderate measures are unreasonable. Banning all electronic devices on airplanes would be a major headache for everyone involved and would probably be overkill, but the risk is still non-zero and asking passengers to turn devices off for a few minutes during the two most dangerous times in a flight is perfectly reasonable.

Banning all electronic devices on airplanes would be a major headache for everyone involved

I think we've seen that this is not a problem for the Powers that Be. It's not as if the TSA chairman ever has to fly coach.

and would probably be overkill

I'm certain that we've seen that this is not an obstacle for implementation by the government.

but the risk is still non-zero

(Shrug) Zero accidents out of tens of millions of flights in which you can be pretty sure that at least one passenger has left their phone on. Close enough to zero risk for me.

You're still welcome to get a PPL and have as many cell phones as you wish turned on while you fly.

If you think anything that doesn't directly cause accidents aren't worth regulating, you don't truly appreciate why we have such good air safety.

Letting he pilots chit-chat when landing can't hurt either, right? Millions of successful flights before the sterile cockpit environment idea came about, would perhaps seem like close to zero risk for you, yet we are all safer now because of it.

Life offers you no guarantees, and risk avoidance costs money, time, and convenience. How safe do you want to be? Speaking for myself, I was fine about three nines ago.

That's the problem though. You don't fly thousands of passengers each day and have seen several of your peers bankrupted or seriously financially wounded by a single high profile accident, so you might have a different view on the risks compared to the ones running the airline.

By definition I take far more risk when flying a single-prop light aircraft, and I'm fine with that. What I don't expect is to be able to force that risk level on other people.

But you haven't shown that there is any risk, and neither has anyone else. Which (again) is why we're still allowed to bring electronic devices up to and including cell phones onboard passenger aircraft.

You can't run a civilization on the Precautionary Principle. You understand that, right? Most people understand that, but the TSA and (until now) FAA don't seem to.

It's trivially easy to show that there is a risk of interference, the question is just how big the risk is, and whether turning devices off during takeoffs and landings is worth the inconvenience.

And as mentioned elsewhere there had been reproducible incidents of interference reported, which was the initial reason for the ban.

While I have long maintained that the ban is most likely not necessary, I'd much rather have he FAA make that decision and wait a few years until they have done enough studies and collected enough data.

I agree that we can't run the entire civilization on a precautionary principle, but then again that's not what we're talking about. We're talking about 10-20 minutes of inconvenience during critical flight phases. And believe me I hate the beurocracy and often overreaching rules of the FAA (or EASA in my case), but again I appreciate that we would not have he current air safety record without it. In fact, the FAA is usually reactionary in that they usually only act when fatal accidents have happened. (Pilot and crew rest hour limits is one very recent example).

But you haven't shown that there is any risk, and neither has anyone else.

Shouldn't it be the other way around? Shouldn't the onus be on proving that there is no risk, not that there is?

That's called the Precautionary Principle.

It would have kept us confined to the caves, if not the trees.

And it's the reason why flying is no longer only for the adventurous willing to risk their lives. Too bad you don't appreciate that and seem to take it for granted.

Here's an example of the kind of logical trap you are falling into: http://boingboing.net/2010/11/19/odds-of-cancer-from.html

And I could point to lots of counterexamples like Deepwater Horizon. What's your point, that you would be happier with a riskier aviation industry? As I said, get a PPL, or better yet start an airline and start lobbying against FAA rulings.

And I could point to lots of counterexamples like Deepwater Horizon.

Yes, clearly we should... um, do what?

What's your point, that you would be happier with a riskier aviation industry?

My point is that many of the things that annoy passengers don't have anything to do with quantifiable risk. Suggest reading some Feynman, specifically his essay on "Cargo cult science."

As I said, get a PPL

That wouldn't give me any special authority on the subject. These questions must be answered analytically, not with fearmongering from bureaucrats or anecdotes from pilots without RF engineering credentials.

I've read the cargo cult essay. Would you say that based on their actual performance, you would place the aviation industry or the FAA in that category? If so, could you point to other, more successful industries?

I suggested getting a PPL to get rid of all those annoyances that commercial air transport impose on you to reduce their risk. There is even an experimental airplane category if you want to err on the risky side.

I agree that it has to be approached analytically, but since you can't prove a negative, in the end you have to make a risk assessment. I certainly don't agree with all of them, but there have been enough examples of fatal accidents when the FAA didn't do their job, that I'm happy that they are taking their time to, guess what, do the analytical work, before changing a regulation. As opposed to acting on a gut feeling about what would be safe.

I should have said "acceptable risk" not "no risk".

This rests on the false premise that everything is stacked against the consumer. It isn't; there's a balancing of risks that takes place, but you clearly have an axe to grind so I'll let you get on with it.

I'm the one with the axe to grind?!

Dude, if I said the sky was blue, you'd post a response to Hacker News insisting it was green.

Agreed. And there's been a few cases of (presumably poorly shielded) laptops in the 90s causing interference, to the point where the pilot would see the effect appearing/disappearing when the passenger turned on/off the laptop. The ban came about as a proactive measure because of these reports.

Remember that a radio is useless if you can't tune it to a certain channel. If the avionics can tune to various navigation channels, then they can probably reject noise from shitty electronics.

I wonder how much power it takes to desense a GPS receiver, however.

I wonder how much power it takes to desense a GPS receiver, however.

Terrifyingly little, it turns out. Signals from the GPS constellation are about as 'bright' as a light bulb several thousand miles away, and the modulation format usable by civilian receivers is not exactly jam-resistant.

Thankfully there's no reason for a GPS antenna on an aircraft to look anywhere but straight up. It can be well-shielded against interference from within the cabin. Still, GPS interference is a real, reproducible and documented issue, unlike the cargo-cult science being discussed here.

> My understanding (from a pilot friend of mine) that it is really about radio interference with the pilots' radios

If it was the case, this would be a complaint we hear from pilots every day. Think of how many people simply forget to turn off their cell phones...

In the past few years I've noticed this pattern more and more - flight attendant asks passenger to turn off iPhone, passenger simply pushes the top button to turn off the screen, flight attendant accepts this. So flight attendants either don't know or don't care that turning the screen off doesn't turn off the device.

I'd be willing to bet that most people don't bother to actually turn off devices / switch to airplane mode. On a flight last month I even watched a guy turn off the screen on his iPad when asked to shut it off, then as soon as the attendant walked away he turned it on again and continued to use it throughout take-off.

Not necessarily. Avionics fail all the time and it's pretty much impossible for pilots to pinpoint a specific incident to cell phone interference. I've had at least one incident where the pilot came in the PA and asked us twice in flight to make sure all electronic devices were off, because they had problems with the instruments.

As far as I understand it [studied electronics engineering and a private pilot] the main problem is with faulty devices. Although it is very unlikely, a faulty device potentially can act as nasty source of interference at _any_ frequency. Effectively blocking this frequency.

And although it is not a problem for a pilot in normal conditions, it could be a factor that complicates things for a pilot. If the visibility on a takeoff/landing is bad, there is traffic congestion, air traffic control is stretched to the limit you'd definitely don't want a faulty cell phone suddenly jamming an ILS approach system ;)

I'd love to see some real-world examples of this sort of thing. The inverse-square law coupled with the power output of your average iPod makes me seriously question how effectively even a seriously fritzing device could interfere with communications.

I'm sure it happens (the post a bit back about the guy's laptop that was broadcasting mic input due to wacky wiring is a great example), but I'm really dubious that it's significant enough to actually interfere with comms from a system designed to throw radio signals 200 miles.

The power density from a 5MW transmitter at 1km and 100 10W cell phones at 10m is about the same. But you have to remember that the navigation antennas are outside the metal body of the plane, so the phones probably don't matter.

Sometimes you hear interference from GSM phones because the TDMA time divisions are in the AF range, but that's really a function of the power envelope rather than the power of the transmitter. I don't even really count this because I've never seen a GSM phone interfere with a non-part-15 device. Radios have to reject nearby signals; noise well outside their frequency range is even easier to reject. (I've never heard anything like GSM interference while operating my HF radio, either, and I have a GSM phone.)

Take a look at the description of ILS system. Markers - 75MhZ, 3 Watt; Localizer - 108 MhZ, 50 Watt.

These are local nav systems, not FM stations that put kilowatts into the air.

Not any frequency, the radios have physical limitations that only allow them to transmit on a small range of frequencies. They can certainly cause interference outside of the bands they were designed to operate on, though.

Yes, any frequency. Remember we are talking about a faulty piece of electronic. With some pretty weird fault. Not just a transmitter operating in an almost normal mode.

Take an ILS (instrumental approach) frequency 108Mhz. Any piece of wire of around two feet (half dipole) can be a pretty effective antenna at that frequency. Say, headset cable + an output cascade of the amplifier self-excited at this frequency? Doesn't happen in real life, but still...

Remember that your faulty headphones are inside a big faraday cage, and the nav antennas are outside.

I am not sure how much effect this has, but it's something to keep in mind.

Are airplanes really that effective as faraday cages? If they were, it wouldn't be possible to use a cellphone inside one at all, and this wouldn't have been a debate to begin with.

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