Some people say the funniest things...
In my surfing earlier this week, I came across this article about someone who almost was arrested for having his iPhone in airplane mode.
What really struck me as funny was this quote:
OK, so why didn't he tell me that at all in flight, all he said was i was breaking FAA rules, and also why was everyone else allowed to use their laptops, mp3 players, etc ?? The police officer looked confused, and said he would be right back. He talked to the guy again and then came back and said that the airplane is not shielded for ONLY phones in airplane mode.
This is where a little info would have been a good thing...especially for the flight attendant.
All electronic devices put off electromagnetic radiation, and a shield cannot distinguish between emag radiated from a cell phone (in airplane mode) or radiated from a laptop. A shield which may be able to filter high frequency waves may have difficulty with low-frequency magnetic fields, however. Those aren't something you have to worry about a lot in portable electronics because they are more often caused by ground loops (remember those, bluetrekker). :-) Most of the radiation coming from portable electronics is high frequency signals from things like clocks.
Regardless, any standard electronic device is required by the FCC to *not* radiate above a fairly minimal level at those frequencies. If the device does radiate, the FCC won't allow the device to be sold. Plain and simple. If the device is in the final stages and fails testing, it has to be redesigned or "fixed"...which is often not cheap.
Now if the iPhone hadn't been in airplane mode (which lets you use it like an iPod and turns off the transmit/receive signals), then there may have been an issue.
I noticed in some of the comments that people think the airlines don't want you to use cell phones because they want you to pay tons of money for the phones they provide.
My advisor was been working EMI/EMC about as long as I've been alive. He has a whole host of articles about bizarre things that happened before FCC got serious about preventing unintentional radiation. Until the advent of portable electronics, these sorts of things didn't happen as often. But when electronics started being installed in cars, you suddenly had problems with driving past an airport and your car would turn off. It turns out that the electronics weren't shielded and could be susceptible to interference from the airport radar. Likewise, there are several examples he showed us of airplanes having difficulty with things like navigation when certain portable electronics were used.
Cell phones are a bit different because they *do* radiate a lot more than most devices. They have to in order to transmit their signal.
The wiki article (referenced in the comments) notes that these phenomena interfering with airplane electronics were difficult to reproduce. I don't doubt it! Unless you can actually reproduce the environment exactly, including the other electronics devices and the presence of conductors, there's a high probability you won't be able to reproduce the phenomena. And there's also the issue of high altitude (where radiation levels are higher in general) and charging on the plane body possibly causing induced fields on shielding and minimizing their effectiveness.
Susceptibility is a difficult thing to deal with because you have no idea what environments your device could encounter. The more complex the system, the more difficult it is to predict what could go wrong.
So I think the flight attendant was out of line when he failed to realize that the iphone was in standby mode...but it's not a good idea to be using a cell phone on a plane, either.
What really struck me as funny was this quote:
OK, so why didn't he tell me that at all in flight, all he said was i was breaking FAA rules, and also why was everyone else allowed to use their laptops, mp3 players, etc ?? The police officer looked confused, and said he would be right back. He talked to the guy again and then came back and said that the airplane is not shielded for ONLY phones in airplane mode.
This is where a little info would have been a good thing...especially for the flight attendant.
All electronic devices put off electromagnetic radiation, and a shield cannot distinguish between emag radiated from a cell phone (in airplane mode) or radiated from a laptop. A shield which may be able to filter high frequency waves may have difficulty with low-frequency magnetic fields, however. Those aren't something you have to worry about a lot in portable electronics because they are more often caused by ground loops (remember those, bluetrekker). :-) Most of the radiation coming from portable electronics is high frequency signals from things like clocks.
Regardless, any standard electronic device is required by the FCC to *not* radiate above a fairly minimal level at those frequencies. If the device does radiate, the FCC won't allow the device to be sold. Plain and simple. If the device is in the final stages and fails testing, it has to be redesigned or "fixed"...which is often not cheap.
Now if the iPhone hadn't been in airplane mode (which lets you use it like an iPod and turns off the transmit/receive signals), then there may have been an issue.
I noticed in some of the comments that people think the airlines don't want you to use cell phones because they want you to pay tons of money for the phones they provide.
My advisor was been working EMI/EMC about as long as I've been alive. He has a whole host of articles about bizarre things that happened before FCC got serious about preventing unintentional radiation. Until the advent of portable electronics, these sorts of things didn't happen as often. But when electronics started being installed in cars, you suddenly had problems with driving past an airport and your car would turn off. It turns out that the electronics weren't shielded and could be susceptible to interference from the airport radar. Likewise, there are several examples he showed us of airplanes having difficulty with things like navigation when certain portable electronics were used.
Cell phones are a bit different because they *do* radiate a lot more than most devices. They have to in order to transmit their signal.
The wiki article (referenced in the comments) notes that these phenomena interfering with airplane electronics were difficult to reproduce. I don't doubt it! Unless you can actually reproduce the environment exactly, including the other electronics devices and the presence of conductors, there's a high probability you won't be able to reproduce the phenomena. And there's also the issue of high altitude (where radiation levels are higher in general) and charging on the plane body possibly causing induced fields on shielding and minimizing their effectiveness.
Susceptibility is a difficult thing to deal with because you have no idea what environments your device could encounter. The more complex the system, the more difficult it is to predict what could go wrong.
So I think the flight attendant was out of line when he failed to realize that the iphone was in standby mode...but it's not a good idea to be using a cell phone on a plane, either.