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Cell phones/radios in flight...
So why cant we use cell phones and radios in flight? I know it has something to do with the frequency of radio waves. Why does a radio emit waves, but not a Discman? Will my plane fall out of the sky if Joe Traveler forgets his phone is on? How about if my walkman in my bag gets jostled and accidentally gets switched on? How many cell phones and radios are too many? I know it has something to do with the transponder (the thing that tells the tower where the plane is) and radio wave frequencies.
Can maybe an engineer on here (calling AlphaSigOU) help with an explanation - and incluse soem scientific soundin stuff? I am flying on Friday and I’ll be wondering the whole flight. Thanks. |
This might answer your question partly:
http://news.bbc.co.uk/1/hi/uk/399154.stm and http://www.vnunet.com/lite/News/1140734 |
Re: Cell phones/radios in flight...
Quote:
Another thing is the method of communication of cellular phones. Basically, a cell phone is a radio that relies on its transmission coverage through cells within the line of sight of the cell antenna. Using a cell phone in flight is obviously a not very good idea; at the normal cruising altitude of passenger airliners you have a MUCH greater line of sight; your cell phone might try to access several cell towers within its line of sight (at 35,000 feet your line of sight could be hundreds of miles); that's where overload-prevention features on cell networks might kick in. It's a well known fact that some of the passengers on the doomed aircraft on 9/11 used their cell phones to relay their plight to authorities on the ground. Most airlines have relaxed cell phone usage to include the taxi out to the runway and the taxi in to the terminal; you hafta turn it off before takeoff. The transponder (a contraction of 'transmitter-responder', and usually abbreviated "XPDR") emits a discrete four-digit code that identifies an aircraft to air traffic control. Certain transponder codes are expressly reserved for the following situations: 0000 = reserved for military interceptor jets 1200 = aircraft operating on visual flight rules (VFR) 7500 = hijack 7600 = radio failure 7700 = EMERGENCY If you're flying on United Airlines, most aircraft will carry the radio conversations between your aircraft and ATC. However, this is a feature turned on only at the discretion of the captain. (If you ask nicely, he might relent). It's on Channel 9 of the audio programs. None of the other airlines have this feature. BTW, I'm flying down to Fort Lauderdale tomorrow! :) |
AlphaSigOU is, as always, a fount of information. :)
Here's an amusing story for ya: I was on a plane once where we taxied away from the gate and were then held on the ground (apparently there was a ground stop at our destination and they didn't bother acting on it until AFTER we'd left the terminal :rolleyes: ) - so the plane was parked out of the way somewhere. The captain announced that we'd be delayed about 2 hours. So everyone went for the "obscenely-expensive seatback air phones" to tell friends, family, and colleagues about the delay. About ten minutes later, AFTER everyone had paid $5/min or whatever it's up to now, the captain announced, "Oh, by the way, you can use your cell phones." :rolleyes: :mad: :p |
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