ATA tries to arrest you for using your iPhone in "Airplane Mode"
Oct 11, 2007, 11:13 am
#46
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I completely disagree. On any given flight, I'll bet you there are several cell phones on for the duration of the flight. Why hasn't anything happened? The probability of the cell phone's transmitted signal's harmonics having enough power to interfere with the avionics is about zero unless one puts the avionics into the near field (1 meter or less from the cell phone).
If those avionics were located in the near field, then either the passenger is someplace they shouldn't be, like in the right seat talking on a cell phone, or the plane was so poorly designed that any electronic use is going to interfere with the avionics, including so-called "approved" electronic devices. These approved devices are all antennas - they may not have been designed as such, but that's exactly what they do. They aren't a problem and neither are cell phones with the avionics in the far field (> 1 meter from the phone).
If those avionics were located in the near field, then either the passenger is someplace they shouldn't be, like in the right seat talking on a cell phone, or the plane was so poorly designed that any electronic use is going to interfere with the avionics, including so-called "approved" electronic devices. These approved devices are all antennas - they may not have been designed as such, but that's exactly what they do. They aren't a problem and neither are cell phones with the avionics in the far field (> 1 meter from the phone).
Oct 11, 2007, 11:30 am
#47
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Complex systems enter failure modes not anticipated by their designers.
When you finish testing all possible aircraft with all possible passenger dispositions with all possible combinations of RF-emitting devices in all electromagnetic environments, I'll be glad to review the results and approve allowing passengers to use anything included in the study.
Until you're done, though, I'd prefer to have the pilot's controls connected to the aerodynamic surfaces by cables and hydraulic lines, thank you very much.
(p.s. The 737 rudder problem was caused by a coincidence of factors that never occurred in testing. Haven't we learned anything?)
Oct 11, 2007, 11:38 am
#48
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Inexplicable stuff happens.
A cell phone contains a receiver, which is activated at various times depending on whether or not it's registered on a cell site. All receivers (except TRF or crystal sets) radiate radio frequency energy - that is, they transmit RF whether they're transmitting information or not. A WiFi connection is also a transceiver. Anything with a logic clock in it is a transmitter.
Oct 11, 2007, 12:04 pm
#49
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If the wifi is on but not being actively used, it's usually still trying to communicate with a router or a repeater, though with far less data.
Oct 11, 2007, 12:06 pm
#50
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Even ignoring all of the scientific data (which universally confirms that pax electronic devices have no effect on airplane systems), one thing is certain: If there was any real risk that electronic devices could disrupt safe flight, the airlines and the government regulators would simply ban those electronic devices from the cabin.
That neither the airlines nor the regulators have taken such a position is pretty strong evidence the risks are, well, not substantiated.
That neither the airlines nor the regulators have taken such a position is pretty strong evidence the risks are, well, not substantiated.
Oct 11, 2007, 12:07 pm
#51
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We are in complete agreement.
When you finish testing all possible aircraft with all possible passenger dispositions with all possible combinations of RF-emitting devices in all electromagnetic environments, I'll be glad to review the results and approve allowing passengers to use anything included in the study.
Until you're done, though, I'd prefer to have the pilot's controls connected to the aerodynamic surfaces by cables and hydraulic lines, thank you very much.
(p.s. The 737 rudder problem was caused by a coincidence of factors that never occurred in testing. Haven't we learned anything?)
When you finish testing all possible aircraft with all possible passenger dispositions with all possible combinations of RF-emitting devices in all electromagnetic environments, I'll be glad to review the results and approve allowing passengers to use anything included in the study.
Until you're done, though, I'd prefer to have the pilot's controls connected to the aerodynamic surfaces by cables and hydraulic lines, thank you very much.
(p.s. The 737 rudder problem was caused by a coincidence of factors that never occurred in testing. Haven't we learned anything?)
Shall we stop serving hot drinks? Have we learned nothing?
Oct 11, 2007, 12:14 pm
#52
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my notebook computer has built-in broadband (no need for a PC card with
a little antenna sticking out)
I had once forgotten to turn it off while the plane was somewhere over the
big pond... I immediately turned it off... but continued to use my notebook
for other stuff.
how come no flight attendant has ever bothered me before?
I'm sure my laptop produces more interference than a little iPhone...
a little antenna sticking out)
I had once forgotten to turn it off while the plane was somewhere over the
big pond... I immediately turned it off... but continued to use my notebook
for other stuff.
how come no flight attendant has ever bothered me before?
I'm sure my laptop produces more interference than a little iPhone...
Oct 11, 2007, 12:19 pm
#53
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Oh, No! Not the Pepsi Syndrome!
The probability of serving hot drinks during flight causing a pilot to spill a drink and incapacitate themselve or damage the instruments is about zero, but certainly not non-zero. Is there a spilled drink program in the cockpit simulator?
Shall we stop serving hot drinks? Have we learned nothing?
Shall we stop serving hot drinks? Have we learned nothing?
Oct 11, 2007, 12:28 pm
#54
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Cell phones only transmit when you're in a call.
When a cell phone isn't registered on a cell site, it is listening every seven seconds for one it can connect with (i.e., receiving). It won't wear down its battery any faster than it does when it's switched on in normal use - typically several hundred hours.
Last edited by CessnaJock; Oct 11, 2007 at 1:45 pm
Oct 11, 2007, 12:56 pm
#55
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The problem is (apologies for needing to get technical) that there is no independent electrical ground in an aeroplane in the air. The body of the plane acts as the ground for the electronics, but the phones are inside that ground and so have the potential to modulate it. Rejecting ground interference is a complicated task and one that wasn't necessarily considered back when some of the aeroplanes were designed. You are correct that it is inexcusable for recently designed avionics.
Secondly, cellphones can end up putting interference onto a totally different frequency then they operate on. It's called Intermodulation. The mythbusters, though I like their show, could not have possibly tested all the various setups which could result in intermodulation, because they're so specific and unpredictable (unless you want to spend a lot of time doing really tedious mathematical models). For example, in a big auditorium you might get severe intermodulation on a speaker wire, such that you can hear a local radio station. But, if you move the speaker wire three feet to the left, it's whisper quiet.
Finally do you really know for sure that you iPhone doesn't have a bug which causes intermittent transmissions, even while in airplane mode? No, you don't.
In short, sure, the FA was over-reacting. Any actual problem as a result of your iPhone being used at 10,000ft is exceedingly unlikely, but still remotely possible. But given that there's 100 something people on that flight it seems better to play it safe...
Oct 11, 2007, 12:56 pm
#56
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Has anyone with a real brain and education been able to conclusively say that even having a phone in non-airplane mode is somehow hazardous? I have an engineering background, and I'm convinced it's just a way to get people to turn off their phones so they're paying attention (theoretically) if something bad happens on takeoff or landing.
My evidence:
1. I have left my phone on countless times - mostly accidentally - and all it does is say "No Service" when we're at altitude. This I know to be because cell tower antennae are aimed at the horizon, not up. I have yet to crash due to my blatant disregard for cell phone safety.
2. Planes (and everything else) are bombarded by radio waves in the EXACT SAME frequencies used by cell phones all the time. These radio waves come from the cell towers, and are a lot more powerful than the dinky 0.6 W max that a handheld phone puts out. If cell phone signals are so dangerous to planes, why don't they declare airports and the surrounding airspace to be cell service-free areas?
Hmm?
My evidence:
1. I have left my phone on countless times - mostly accidentally - and all it does is say "No Service" when we're at altitude. This I know to be because cell tower antennae are aimed at the horizon, not up. I have yet to crash due to my blatant disregard for cell phone safety.
2. Planes (and everything else) are bombarded by radio waves in the EXACT SAME frequencies used by cell phones all the time. These radio waves come from the cell towers, and are a lot more powerful than the dinky 0.6 W max that a handheld phone puts out. If cell phone signals are so dangerous to planes, why don't they declare airports and the surrounding airspace to be cell service-free areas?
Hmm?
This has been pointed out by many for a long time -- if in fact mobiles (I refuse to use this ridiculous term "cell phone") COULD "interfere with navigation" and "cause the plane to crash," it would have happened a long time ago. Have you EVER been on a flight and NOT heard at least two dozen mobiles go off with welcome SMS messages as the plane is landing? At least half the passengers forget to turn them off during flight. Nothing has ever happened because of this.
Oct 11, 2007, 12:59 pm
#57
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Here are some other people who have had similar occurances:
no signal at work drains cell phone battery
Several others here
and some more
I do not offer these examples or my own as scientific evidence, nor do I offer my own experience as such. However, these were 3 quick hits using The Google and it seems my experience is hardly an 'anomoly'.
Oct 11, 2007, 1:02 pm
#58
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Secondly, cellphones can end up putting interference onto a totally different frequency then they operate on. It's called Intermodulation. The mythbusters, though I like their show, could not have possibly tested all the various setups which could result in intermodulation, because they're so specific and unpredictable (unless you want to spend a lot of time doing really tedious mathematical models). For example, in a big auditorium you might get severe intermodulation on a speaker wire, such that you can hear a local radio station. But, if you move the speaker wire three feet to the left, it's whisper quiet.
Oct 11, 2007, 1:04 pm
#59
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Battery life gets drained dramatically when there is no connection (unless in airplane mode). Its effect to find a cell site sucks the battery life out real fast.
Secondly, many phones are text-enabled and have GPS. They're transmitting signals all the time to maintain communication. How do you think a cell tower knows where you are when someone calls you?
Don't believe me? Put your idle cell phone next to a speaker or microphone and listen to the noise.
Oct 11, 2007, 1:22 pm
#60
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As long as - rightly or wrongly, I'm not taking any position here - cellphone use is prohibited in-flight, allowing cellphones in airplane mode is idiotic. Who - other than the cellphone's user - is in a position to easily verify whether that thing is in airplane mode?! Do you want FAs to stop at each seat and check each cellphone that is being used?
I was recently on an airline that expressly prohibited using cellphones in airplane mode - SunExpress (small airline serving routes mainly between Germany and Turkey, and within Turkey). Their FAs enforced this, too. I think that airline has it right.
I was recently on an airline that expressly prohibited using cellphones in airplane mode - SunExpress (small airline serving routes mainly between Germany and Turkey, and within Turkey). Their FAs enforced this, too. I think that airline has it right.