Quote:
Originally Posted by jbjb
The trouble is, it's staggeringly hard to quantify the risk.
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Actually, thanks to nowadays instruments and computers, it's very easy.
Ok, to be honest: it's easy to quantify and even foresee
the effects that electronic devices will have on other electronic devices, which I admit is not the same as quantifying the complete risks, but still it's the starting point.
I have here (I have been looking for it at my workplace in the last days) the issue n°4 of 2003 of the monthly
Le Scienze, which is the italian equivalent of
Scientific American, wish I had a scanner to scan the article...
Anyway, in many European countries rules now allow to use PDE (personal electronic devices) on
approved and certified airplanes even during liftoff and landing.
According to the article, to get the "certification" an aircraft doesn't need to change its equipment or add special shieldings: an air company just need to waste the time and money needed to fill the paper for the certification. None of the 104 "certified" italian airplanes has changed, added, or removed anything to its electronics.
The author of the article, engineer Giovanni Torrella, writes that he and three colleagues made several experiments, one of them consisted in using simple radio receivers, bluetooth receivers and EM detectors to identify how many electronical devices were not turned off by passengers during the liftoff and landing of the airplanes. They found out that on average on an airplane there are 14-15 PDEs that aren't turned off when the pilot asks to, probably because they are forgotten in a pocket or in hand luggages, and that roughly 85% of them are mobile phones/smartphones.
The article is actually 6 pages long and has a few interesting tables, anyway I'll just report the most interesting part (to me):
even with as much as 32 radio-emitting devices turned on (mostly are probably cell phones, plus 3g-enabled gadgets, wifi-enabled gadgets and so on), and as much as 51 generic PDEs turned on, airplane's instruments suffered no ill effect, and worked as they were supposed to. The only case of interference (
this is interesting) reported was because a passenger had brought with him a hand-made AM-FM radiotransmitter, which he tweaked to transmit in several different ranges of frequencies, and which was able to cause a shift of 19° in the GPS positioning of the airplane. Luckily, reports the article, airplanes do NOT rely only on the GPS antenna to determine position, so the system was able to correct the error in real-time and transparently.
Why is it interesting to me? Because in my older posts I always forgot how easy it is to jam a GPS signal
It's actually so easy that there are Android applications out there that make your phone jam any GPS device within 2 meters from it. They work, very simply, by adding NOISE in the GPS frequency range, so that any GPS receiver will "hear" the GPS signal covered by the buzzing noise of your phone.The exact same way the British "buzzed" the Germans communications during 2nd world war
way before band-pass filters became cheap.
Anyway, as usual, it's worth repeating that I'm not trying to make people disobey the safety rules on airplanes: I write what I write so that should you see someone playing with his/her iPhone during landing, you don't panic, because whatever you believe about electronic devices on airplanes, the hypothetic dangers they could cause is ten times less of the very real dangers that panicked passengers DO cause!