Fliers Must Turn Off Devices, but It’s Not Clear Why • Hacker News Board

Re: Fliers Must Turn Off Devices, but It’s Not Clear Why

#81

Post by Steko » Mon, Nov 28, 2011, 1:58 AM UTC

trout wrote: post #20

The wikipedia article is more interesting: http://en.wikipedia.org/wiki/Mobile_phones_on_aircraft This sums it up pretty well: "The regulatory agencies and aviation industry take the position that any increased risk is unacceptable if it is avoidable." There's some technical channel sharing problems where phones have access to more towers than designed on land. The FCC can't predict what would happen if phones were a…

They just dont want to say it's ok then get sued to hell whenever a plane goes down.

Re: Fliers Must Turn Off Devices, but It’s Not Clear Why

#82

Post by pyre » Mon, Nov 28, 2011, 2:00 AM UTC

bdonlan wrote: post #65

FaceKicker wrote: post #26

Earlier quoted context omitted.

If they actually aren't willing to test whether cell phones interfere with their equipment, they shouldn't be allowing cell phones on the plane at all. Relying on people's compliance (or even just their attention) to ensure the plane doesn't explode is absurd.

There are other options than "allow free cell phone use" and "frisk all passengers to ensure they're not smuggling in an active cell phone". Asking passengers not to use them is a decent compromise between safety and inconvenience. Naturally, if a crash were to actually occur due to mobile phone use, the FAA would need to revisit this guideline. Note that GSM phones in particular _do_ interfere with radio systems - t…

  > cell networks aren't designed to deal with the rapid
  > tower transfers

I always see this argument brought up (on HN), but what does the FAA care about cell carriers' networks? Why don't they ever use this justification when asked to justify their policy?

Re: Fliers Must Turn Off Devices, but It’s Not Clear Why

#83

Post by MatthewPhillips » Mon, Nov 28, 2011, 2:00 AM UTC

mikeash wrote: post #68

MatthewPhillips wrote: post #62

Earlier quoted context omitted.

How do we know there isn't a bug in a device's airplane mode?

How do we know there isn't a bug in a device's off switch? Most of them are software-based these days.

Most of them allow you to take the battery out if it comes to that.

Re: Fliers Must Turn Off Devices, but It’s Not Clear Why

#84

Post by pyre » Mon, Nov 28, 2011, 2:02 AM UTC

ArchD wrote: post #73

gchucky wrote: post #11

MythBusters covered this awhile back, and busted the myth: "The final explanation is that, even though the airplanes appear to be well-shielded against cellphone interference, there are so many different electronics in a cockpit, as well as so many different cellphones constantly coming out, the FAA doesn't want to do the necessary testing."[1] [1] http://kwc.org/mythbusters/2006/04/episode_49_cellphones_on_...

I thought preventing unwanted interference between devices was what FCC rules were for. Couldn't they design aircraft equipment to tolerate radio waves from devices meeting certain FCC standards?

That costs money though. There's a reason that a good number of the planes in use are decades old.

Re: Fliers Must Turn Off Devices, but It’s Not Clear Why

#85

Post by arn » Mon, Nov 28, 2011, 2:03 AM UTC

lucasjung wrote: post #79

RandallBrown wrote: post #52

Earlier quoted context omitted.

but wouldn't it make sense for Apple to pay to do the testing? Being able to say "The iPhone is the only phone you can use during your whole flight" would be worth quite a bit of money to them.

They would have to test every model of iphone against not only every model of commercial airliner in operation in the U.S. (including puddle-jumpers), but against every major variation in avionics suite among each model. This testing is not cheap. Even for Apple, it would be prohibitively expensive.

one airline should go halvsies with Apple.

Delta... the only airline you can use your iPhone 4S from takeoff to landing...

Re: Fliers Must Turn Off Devices, but It’s Not Clear Why

#86

Post by ceejayoz » Mon, Nov 28, 2011, 2:06 AM UTC

Bud wrote: post #8

There is actually a very logical, sensible reason to have everyone power off and stow their devices during takeoff and landing, and this story disappointingly failed to cover it: By far the most likely time for any accidents or incidents to occur is during takeoffs and landings. If everyone has 15 objects out and is busily typing away, it's going to be tht much more difficult for flight attendants to get everyone's a…

> If everyone has 15 objects out and is busily typing away, it's going to be tht much more difficult for flight attendants to get everyone's attention to give instructions, and crucially, much much more difficult to evacuate the plane as quickly as possible.

I'd imagine the screaming, flailing, flickering lights, smoke, and vibrations would do a decent job of getting people to look up from their iPhones.

> It's the same reason they aren't serving food and drinks at those times, and the same reason you have to stow your carry-ons and put your tray tables up at these times.

None of those restrictions are in place to make you listen to the attendants. They are in place because takeoff/landing is generally the part of the flight that is bumpiest and with the most maneuvering. Flight attendants (legitimately) don't want to clean soda off the ceiling or get hit by a suitcase.

Re: Fliers Must Turn Off Devices, but It’s Not Clear Why

#87

Post by mgkimsal » Mon, Nov 28, 2011, 2:07 AM UTC

teraflop wrote: post #55

mgkimsal wrote: post #53

Earlier quoted context omitted.

How do you actually "turn off" a kindle (e-ink)? AFAICT, it's always "on", although you can turn off the radio part (which I rarely have on anyway).

Like most such devices, if you hold down the power switch for several seconds it will turn itself off completely. That said, I'd be surprised if more than a tiny fraction of Kindle owners know this option exists.

had mine for 2+ years (got the second iteration the day it was released) and never knew this.

Re: Fliers Must Turn Off Devices, but It’s Not Clear Why

#88

Post by dfox » Mon, Nov 28, 2011, 2:07 AM UTC

bdonlan wrote: post #65

FaceKicker wrote: post #26

Earlier quoted context omitted.

If they actually aren't willing to test whether cell phones interfere with their equipment, they shouldn't be allowing cell phones on the plane at all. Relying on people's compliance (or even just their attention) to ensure the plane doesn't explode is absurd.

There are other options than "allow free cell phone use" and "frisk all passengers to ensure they're not smuggling in an active cell phone". Asking passengers not to use them is a decent compromise between safety and inconvenience. Naturally, if a crash were to actually occur due to mobile phone use, the FAA would need to revisit this guideline. Note that GSM phones in particular _do_ interfere with radio systems - t…

That characteristic GSM interference is actually quite harmless to most well designed systems. In some sense, the GSM buzz is more caused by bad design of the audio amplifier than anything else. Also it's mostly caused by nearfield magnetic effects in contrast to RF emissions. I think it's safe to say that this is completely irrelevant to most avionics systems (but nobody is going to guarantee that).

Re: Fliers Must Turn Off Devices, but It’s Not Clear Why

#89

Post by ceejayoz » Mon, Nov 28, 2011, 2:11 AM UTC

politician wrote: post #72

dmarquis wrote: post #48

Earlier quoted context omitted.

The method used in that article is just counting flight incidents in some historical data that may possibly have been caused by interference. The evidence that consumer electronics are the cause is just anecdotal: "In one telling incident, a flight crew stated that a 30-degree navigation error was immediately corrected after a passenger turned off a DVD player and that the error reoccurred when the curious crew asked…

After a 30-degree navigation error was corrected by turning off a DVD player, would the pilot seriously endanger the aircraft by asking the passenger to turn it on again to test? Anecdotal, and probably completely false.

> After a 30-degree navigation error was corrected by turning off a DVD player, would the pilot seriously endanger the aircraft by asking the passenger to turn it on again to test?

No?

1. It was already demonstrated that turning it off fixed it. If you see the instruments goof up again, you tell the guy to turn the player back off.

2. Pilots are extensively trained to deal with equipment failures, including total loss of power and instruments.

Re: Fliers Must Turn Off Devices, but It’s Not Clear Why

#90

Post by CamperBob » Mon, Nov 28, 2011, 2:13 AM UTC

aceofspades19 wrote: post #74

wglb wrote: post #36

Earlier quoted context omitted.

Inside your iPod nano, or any other device with a computer chip is a radio transmitter. Inside the cockpit are many radio receivers, some of which are pretty critical to the proper flight of the airplane. Your radio transmitter, and radio transmitters being run by other passengers, mix and mingle their signals, producing an unpredictable effect on these key cockpit receivers. The probability that this happens is not…

1. Not all devices with a computer chip have radios, my TI-84 calculator has a Z-80 processor but there is no radio in it 2. Aircraft radios operate on a very different frequency then consumer electronics, and I'm pretty sure the FCC wouldn't allow consumer electronics to operate on the same frequency as the radios in a cockpit regardless

Technically, yes, there is a "radio" in your TI-84. The Z-80 is clocked by a crystal oscillator, which runs at a few MHz. Some of that energy will escape in the form of electromagnetic radiation. Sensitive instruments (including an ordinary AM radio) can pick up this radiation from distances ranging from a few inches to several yards. This is true of essentially all modern electronics, although the frequencies have obviously gone higher and higher over time.

If it were true that the RF energy levels emitted by FCC Part 15-covered consumer electronics could interfere with aircraft systems, it would be utterly unthinkable to permit them on board in the first place, whether "powered off" or not. The TSA would be confiscating Game Boys, not bottles of water. Since that isn't happening, it's difficult to avoid the conclusion that the prohibition is just one more exercise in bureaucratic security theatre.