From a Westerner in China:
Something doesn't seem right about the methodology the FAA is using to test for interference from devices. I work in the Medical Device industry (highly regulated, as is the aerospace industry) and have taken several devices through the electronic emissions testing process . The way it works today is that you must test to see if a device is affected by emissions from other devices (susceptibility) and if it can affect other devices (emissions). Of course, you can't test your device in every possible environment, nor would you want to as there may always be situations you didn't anticipate. Yet that is the way the FAA seems to be proposing testing the Kindles and so forth.From a reader in the math/tech world:
Here's the way it works in the real world. Manufacturers adhere to a testing regimen agreed upon by a recognized standards body. For emissions they provide a curve that shows allowable energy levels at all frequencies and you have to demonstrate that in all possible use cases for your device (booting up, charging, running the processor at 100%, etc) you fall below that curve at every point. On the susceptibility side (the airplane in this case) the standards body provides a different curve which dictates a broadcast pattern at all frequencies. You have to demonstrate that your device doesn't malfunction dangerously when subjected to these emissions.
So, if the FAA wanted to come up with a new emissions standards, all the manufacturers would rush to demonstrate compliance or to re-engineer to achieve compliance. The susceptibility side is more difficult, because in this case we are bringing the emitters inside the device (the airplane). But I could conceive of an agreed upon standard testing regimen which, coupled with the appropriate emissions standard, could demonstrate safe and effective use (that last is a FDA Medical Device term and I'm sure there is an FAA equivalent to it).
This is all unbelievably silly. Shouldn't planes be made safe enough so that one silly kindle couldn't bring them down? This is (obviously) the way to test them:From another person in the software/tech world:
1. Take a healthy representative sample of the devices out there.
2. Look at the kinds of radiation they produce.
3. Find some kind of maximal radiation that they could produce under any circumstances.
4. Ask the manufacturers if we've missed any wavelengths/frequencies/strengths and update the radiation profiles as required.
5. Certify the planes for that (upgrading any shielding as required).
6. Insist all new devices stay under those limits to be "airplane safe" (much like the certification they receive now for other purposes).
7. If for some reason a new device comes along that needs to produce more or different kinds of radiation then repeat 1-6.
End of problem. Still pretty expensive and time consuming (and probably unnecessary), but at least doable.
The idea of testing every device belies the policy's mis-purpose. There is not - for all practical purposes - a finite list of electronic devices with on-off switches. The long-tail of lesser-spotted devices is gigantic, practically impossible to collect and test, and paradoxically the the very place where a RF-mis-behaving device will likely be found, if any such exist.From a reader in the South Pacific:
Why? because you can be damn sure that the engineers who designed all the greater-spotted devices (and the FCC regulated) are not giving away any of their precious battery juice to random RF. If an RF-mis-behaving device exists, it's probably some random widget manufactured in small numbers outside the US/EU, and not subject to RF testing/regulation.
So presuming some testing of 'top 100' devices takes places, it will be yet another piece of theater - doing little to detect the real threat, if it exists at all.
All of this, of course, in light of fact that the real rule - for all practical purposes - is that devices should be out of sight, not turned-off
Maybe I'm missing something, but isn't it patently obvious that electronic devices cannot possibly bring down an airliner? After all, if it were possible it would have been done a long time ago. All that would be necessary is to fill up the cabin with would-be terrorists with cell phones, Kindles, iPads, etc. and have them turn them all on as soon as the captain announces "Flight attendants, please take your seats." A lot easier and less messy than stuffing your shorts with incendiary devices.And, on the other hand, from a reader in mainland America who is also in the tech world:
By the way, you probably know that the "Mythbusters" guys tested this premise a few years ago with an extremely powerful radio transmitter in the cockpit of a plane and found no interference whatsoever with the plane's systems. At the end of the program I was hoping they'd say "Well, this dispells any idea that an iPhone can bring down a 777", but they wimped out and said "Well, we found it can't be done, but we still recommend turning everything off."
Although I personally agree that the rule is stupid and agree with the empirical observation that it's been violated endlessly with no crashed attributed to it, I will take issue with your reader who wrote:My own beliefs are closest to the "reader in the South Pacific," but the suggestions before that make sense to me. Still, I'm not holding my breath for a change. And meantime, with millions of miles of commercial air travel over the decades, I am still waiting for the first time any member of a
"My Kindle and my MP3 player are both have 'FFC approved' symbols."
I believe you have already commented in your blog that just because the design meets FCC regs, it doesn't mean that every unit still meets the regs while it's in the consumer's hands on the aircraft. I have a microwave over that knocks out my satellite internet when cooking at high power. No doubt FCC approved, but it clearly impacts communications devices. I have no idea if the oven is non-conforming, the satellite system is non-conforming, or if the standards aren't tight enough.
This brings to mind the issue of Lightsquared, which is trying to create a national broadband network. They own spectrum adjacent to the GPS spectrum. Tests show they will knock-out most consumer devices. It turns out that the receivers don't conform to the standards for rejecting noise from adjacent spectrum. The problem is not with the broadcast signal, or at least that's my reading of the latest round of this battle. The point is that perhaps your laptop is does meet FCC standards, but that still doesn't mean that it won't interfere (let alone the issue of your laptop plus everyone else's RF emitting device all jammed inside a big reflector.)
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