FAA To Allow Use of Most Electronic Devices Throughout Flights 221
alstor writes "As previously expected, the FAA has announced that most portable electronic devices may be used throughout the duration of a flight. Mobile phones may still only be used in airplane mode without cellular service."
Re:Keep the phone ban (Score:3, Informative)
there is no way you will get a connection to a tower at 35000 feet moving at 500mph
Yes you can. If you will recall, this was proven on 9/11/2001.
Re:Keep the phone ban (Score:4, Informative)
Re:Keep the phone ban (Score:5, Informative)
there is no way you will get a connection to a tower at 35000 feet moving at 500mph
Yes you can. If you will recall, this was proven on 9/11/2001.
The prohibition on using cell phones was also at the request of the wireless carriers. The cellular system was not designed to handle someone using their phone at 35,000 fett and traveling at 500 mph. Your phone "sees" way too many towers and yet the towers have to hand off rapidly since you move out of coverage really fast at that speed. Seven miles up in an airplane is not that far from a tower and the signal is excellent.
It's easier to "just say no" than it is to re-engineer the cellular network to also work with people using their phones in airplanes. Besides, the airlines want you to use their skyphone at their rates so it's in their interest to keep you from using your cell phone instead.
Cheers,
Dave
Re:Keep the phone ban (Score:5, Informative)
Given that aircraft fly around in a veritable EM soup (AM, FM, VHF transmission towers, the spark gaps of an angry god [wikimedia.org], etc.), I would hope that every phone on the plane draining its battery in a coordinated RF scream would be a survivable event. Whether all the chatter raises the noise floor or introduces errors into sensitive measurements is a subtler but more likely issue.
What is outside the airplane is the least of the problems. A large commercial plane has racks of electronic equipment, dozens of radios, weather radar, flight displays, in-flight entertainment systems, power generation and distribution systems, pumps, servos,...etc.
All of those are potential sources of EMI that need to work together as a system. The only reason a cell phone is considered 'risky' is because it un-tested. There is nothing unique about cell phone electronics from an avionics point of view. Similar, and more powerful, systems are already integrated into the airframe.
Re:Keep the phone ban (Score:5, Informative)
I like to use this ABM1 - Passive Air Band Monitor [ramseyelectronics.com] when flying. I keep it discreet as I'm sure most flight crews won't understand how it's different from a typical radio receiver. I regularly hear that "bzz bzz bzz" of cell phones with this device. I then ask my girlfriend sitting next to me if she put her phone in airplane mode. If she hadn't and does it the noise usually goes away. If she had her's in airplane mode then I assume it's someone else sitting near me.
Correct so far.
Phones do cause interference in the aircraft frequency bands (at least at short range).
And... you go off the rails.
GSM phones cause interference in audio-frequency circuits because the phone transmits in regular bursts every 4.62 ms (this is why it doesn't affect CDMA, UMTS, etc., only 2G GSM/GPRS/EDGE, because they use TDMA). It turns out audio amplifiers generally tend to serve as decent wide-band AM receivers, so this is very easily picked up as a 217Hz buzz. However, this is all happening on the audio-frequency side, so calling it "interference in the aircraft frequency bands" is just plain wrong -- it will affect practically any unshielded or insufficiently-shielded device (it's only a couple watts or so transmitter, but within a meter or less the inverse-square law says you do need better shielding than a lot of consumer electronics have) with an amplified audio output, including all sorts of radios, and non-radio devices from MP3 players to cassette players.
(for more on this, google or start here [techmind.org])
Fortunately, it's a really easy problem to solve -- just keep your phone out of the cockpit. Thanks to the inverse-square law, it's really only a practical issue at very short range.
Re:Keep the phone ban (Score:5, Informative)
And they were using cell phones.
Most of the 9/11 calls were from Airfones, not cell phones -
http://imgs.sfgate.com/blogs/images/sfgate/cmcginnis/2010/12/16/airfone250x187.jpg [sfgate.com]
Airfones have mostly gone away, but a dozen years ago they were pretty common.
When I notice my fellow passengers playing Candy Crush on their phones you can plainly see the NO SERVICE displayed on the top. This is because they don't know how to go into Airplane Mode so their radios are on, but the phone can't lock to a tower at 35K feet travelling at a ground speed of 500 mph.