antennaman
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There is so much incorrect information in this thread, along with a good deal of hard nosed tone to the messages that I considered whether or not to respond for some time.
But, perhaps you would like to learn the reason for the ban in flight. I am a consultant to the cellular industry in such matters.
It's not primarily about interference, although that possibility does exit. One 800 or 1900 mHz device working within an aircraft could be but probably is not a major issue, but once 10, 15 or more are all transmitting and receiving, the possibility for inter-modulation (I'm not going to get into definitions; suffice it to say the cumulative and multiplicative effect of many transmitters and receivers all working on slightly different frequencies) does increase.
These "IM" products have the possibility to interfere with communication and navigation equipment. Will it, as another poster so eloquently said, "bring down" the plane? No. Will the effect possibility render an ILS, GPS, Pegasus, ACARS, or other sensitive radio gear in the plane flaky? Possibly...and flaky, in flight, generally means don't use it....which could make the flight more difficult....and therefore dangerous.
This effect is exacerbated if the interference source is near the mounting location of the affected device. Not all comms equipment (for that matter, almost none of it) is located in the cockpit. It's scattered all over the plane. One of our "knowledgeable" heroes Horace, perhaps a commenter here, might be seated 6' from an aircraft radio device trying to resolve a low level radio signal coming from miles away, and without knowledge, generate an IM product slap-dab on frequency.
On a clear bright summer day, if a plane has a flaky ILS or can't communicate with it's Pegasus or ACARS, no big deal. The pilot taps on it, scratches his head, lands the plane, and writes it up.
However, I would not want to lose that ILS, or even have it go flaky for a second, at 200' altitude on final on a driving snow night while landing because Horace in seat 19B "knows" it won't hurt the plane.
However, another REAL issue, perhaps more near and dear to we phone freaks, is what it does to the cellular systems. The FCC requires compliance, and as a Part 121 or 135 carrier, your airline must help them have you comply:
Cellular technology, over 'old fashioned' IMTS systems which it replaced, is based upon one, single, unavoidable issue: reuse of frequencies. Old mobile phone systems covered miles and miles with their base stations.....a city the size of Chicago had one base station, and 24 channels at most.
Cellular reuses those channels over and over again with relatively low-lying base station sites, with a limited (by comparison) 'illumination' area....they cover a few miles at maximum. Ten or fifteen miles away, (sometimes more, sometimes less) those frequencies are used again. You can use your phone because your phone can't "hear" the same frequency being used at the distant cell site (and dozens others in that, perhaps, tri-county area). Same with the guy on the same channel on the other site not being disrupted by you.
Now, we take one of us, and place our transmitter at 10, 15, 20, or more THOUSAND feet.
Instead of a 2-8 mile 'range' of our phone to a base station, we now (at 20,000 feet) have a 'radio horizon' of 200 miles in every direction....a circle (not perfectly round because you are in an aluminum tube) of 400 miles in diameter.
Can you IMAGINE for a moment how many cellular base stations, using the frequency you are currently using, are now "illuminated" by that signal? It's dozens, and dozens.
So, while you are doing it, you are interfering with calls on the ground....and, since your phone cannot 'hand off' as it normally does, you will experience poor call quality while you are causing this havoc. And, your phone may be 'heard' by two systems at once, and each system attempt to give it instructions for call handling.
Ever notice how mobile operation is degraded when using the phone at comparatively great elevations (rooftops of skyscrapers, etc)? Same effect, both ways.
Now, there are exceptions, and I'm sure I will hear them....."I used my phone once on a plane to Peoria for 20 minutes and blah, blah, blah", or "I never had a problem on a rooftop". These nonscientific, colloquial results are exceptions; what I've explained here are the REASONS for the problem.
Are the airlines going to give a lesson in radio propagation to Suzi when telling her that her phone needs to be off? Nope. The simple answer is safety, and it does have some basis in fact. If Suzi and 17 others were all using their phones, there WOULD be a problem.
So, may I suggest that we as above-average, much-more-technically-informed folks consider these points, and understand what REALLY does happen? It's not a dark conspiracy to make money.....it's simple, (very simple) technology.
But, perhaps you would like to learn the reason for the ban in flight. I am a consultant to the cellular industry in such matters.
It's not primarily about interference, although that possibility does exit. One 800 or 1900 mHz device working within an aircraft could be but probably is not a major issue, but once 10, 15 or more are all transmitting and receiving, the possibility for inter-modulation (I'm not going to get into definitions; suffice it to say the cumulative and multiplicative effect of many transmitters and receivers all working on slightly different frequencies) does increase.
These "IM" products have the possibility to interfere with communication and navigation equipment. Will it, as another poster so eloquently said, "bring down" the plane? No. Will the effect possibility render an ILS, GPS, Pegasus, ACARS, or other sensitive radio gear in the plane flaky? Possibly...and flaky, in flight, generally means don't use it....which could make the flight more difficult....and therefore dangerous.
This effect is exacerbated if the interference source is near the mounting location of the affected device. Not all comms equipment (for that matter, almost none of it) is located in the cockpit. It's scattered all over the plane. One of our "knowledgeable" heroes Horace, perhaps a commenter here, might be seated 6' from an aircraft radio device trying to resolve a low level radio signal coming from miles away, and without knowledge, generate an IM product slap-dab on frequency.
On a clear bright summer day, if a plane has a flaky ILS or can't communicate with it's Pegasus or ACARS, no big deal. The pilot taps on it, scratches his head, lands the plane, and writes it up.
However, I would not want to lose that ILS, or even have it go flaky for a second, at 200' altitude on final on a driving snow night while landing because Horace in seat 19B "knows" it won't hurt the plane.
However, another REAL issue, perhaps more near and dear to we phone freaks, is what it does to the cellular systems. The FCC requires compliance, and as a Part 121 or 135 carrier, your airline must help them have you comply:
Cellular technology, over 'old fashioned' IMTS systems which it replaced, is based upon one, single, unavoidable issue: reuse of frequencies. Old mobile phone systems covered miles and miles with their base stations.....a city the size of Chicago had one base station, and 24 channels at most.
Cellular reuses those channels over and over again with relatively low-lying base station sites, with a limited (by comparison) 'illumination' area....they cover a few miles at maximum. Ten or fifteen miles away, (sometimes more, sometimes less) those frequencies are used again. You can use your phone because your phone can't "hear" the same frequency being used at the distant cell site (and dozens others in that, perhaps, tri-county area). Same with the guy on the same channel on the other site not being disrupted by you.
Now, we take one of us, and place our transmitter at 10, 15, 20, or more THOUSAND feet.
Instead of a 2-8 mile 'range' of our phone to a base station, we now (at 20,000 feet) have a 'radio horizon' of 200 miles in every direction....a circle (not perfectly round because you are in an aluminum tube) of 400 miles in diameter.
Can you IMAGINE for a moment how many cellular base stations, using the frequency you are currently using, are now "illuminated" by that signal? It's dozens, and dozens.
So, while you are doing it, you are interfering with calls on the ground....and, since your phone cannot 'hand off' as it normally does, you will experience poor call quality while you are causing this havoc. And, your phone may be 'heard' by two systems at once, and each system attempt to give it instructions for call handling.
Ever notice how mobile operation is degraded when using the phone at comparatively great elevations (rooftops of skyscrapers, etc)? Same effect, both ways.
Now, there are exceptions, and I'm sure I will hear them....."I used my phone once on a plane to Peoria for 20 minutes and blah, blah, blah", or "I never had a problem on a rooftop". These nonscientific, colloquial results are exceptions; what I've explained here are the REASONS for the problem.
Are the airlines going to give a lesson in radio propagation to Suzi when telling her that her phone needs to be off? Nope. The simple answer is safety, and it does have some basis in fact. If Suzi and 17 others were all using their phones, there WOULD be a problem.
So, may I suggest that we as above-average, much-more-technically-informed folks consider these points, and understand what REALLY does happen? It's not a dark conspiracy to make money.....it's simple, (very simple) technology.
