Turning off electronic devices when taking off

[zeus60]

I took a brief vacation this past weekend. At the start of one of the flights, the flight attendant told us to turn off all electronic devices. They had to be powered off, not just put into airplane mode. I know this is standard practice, and the fear is that electronic devices will interfere with the planes navigation system (I think that's what I heard once). My question is, is this really necessary? I know the FAA is very paranoid, and I'm not criticizing them for that, but I just wonder how real the danger is.

As a side note, I was once again reminded how much crap people bring on board airplanes.

[kenlilly106]

I think there's 2 main reasons behind it:

1. Nowadays when new wireless enabled devices are coming out monthly, it would be near impossible to test all of them on all of the aircraft flying to see if they cause interference, much easier to do what they do now.
2. I've also read that part of the reason is to make sure everyone can hear all of the preflight safety and related information.

Ken

[vince14]

It's not so much the effect on flight systems, more the fact that they need the pax not to be distracted (by wearing headphones etc) during the two phases of flight when accidents are more likely to occur - take off and landing. Other than that, it's down to the individual airline as to what they allow to be switched on during cruise.

Vince

[zeus60]

I hadn't thought about the distraction part of it.

[jester292]

A lot of people think its harmless, and maybe it is, but it is federal law, and is against the law when you keep your device on when you are instructed to turn it off.

Aaron

[Wayne S]

I think there's 2 main reasons behind it:

1. Nowadays when new wireless enabled devices are coming out monthly, it would be near impossible to test all of them on all of the aircraft flying to see if they cause interference, much easier to do what they do now.
2. I've also read that part of the reason is to make sure everyone can hear all of the preflight safety and related information.

Ken

Personally, I think it is just a BS thing, Just like phones used at the gas pumps and used in Hospitals.

Wireless devices are controlled by the FCC who pretty much gives the frequencies a device may use, Those frequencies are passing through the aircraft all the time, satellites, radio towers etc. etc.

Frankly if one was to ask me what the true reason behind the nonsense in the air is "my guess", It might be the fact there could be others who are using the same channel, when one is in an aircraft they will jump from tower to tower, could even be a licensing deal with those who use/own said towers. I am guessing people actually make aircraft phones and want to be paid/ keep in business by "celling" them .

Edited August 18, 2011 by Wayne S

[Aaronw]

I don't have a lot of flying experience but I flew to Hawaii last summer and we were just asked not to use any electronic devices during take off / landing, not that they had to be turned off or even set to airplane mode, just not actively used. Three different airlines between there and back, United, Hawaiian and US Air but maybe it differs by airline?

This makes me think Vince may be onto something.

[KursadA]

Personally, I think it is just a BS thing, Just like phones used at the gas pumps and used in Hospitals.

Wireless devices are controlled by the FCC who pretty much gives the frequencies a device may use, Those frequencies are passing through the aircraft all the time, satellites, radio towers etc. etc.

It certainly is not BS. The fact that a wireless device is FCC certified does not mean that FCC tested it for all possible interactions with other devices in the vicinity; and such testing is impossible anyway. There have been many well-documented cases where the use of a PED (personal electronic device) on board has caused interference resulting in temporary disablement of important avionics.

Consumer devices that meet FCC emission limits can exceed safe interference limits set by the FAA for avionics, because the FCC and the FAA do not harmonize their regulations.

In March 2004, acting on a number of reports from general aviation pilots that Sams_ung SPH-N300 cellphones had caused their GPS receivers to lose satellite lock, NASA issued a technical memorandum that described emissions from this popular phone. It reported that there were emissions in the GPS band capable of causing interference. Disturbingly, though, they were low enough to comply with FCC emissions standards.

In one telling incident, a flight crew stated that a 30-degree navigation error was immediately corrected after a passenger turned off a DVD player and that the error reoccurred when the curious crew asked the passenger to switch the player on again.

The quotes above are from a well-known (in the electrical engineering community anyway) article from IEEE Spectrum. I suggest anyone who does not believe PED interference to be a flight safety risk to take a look:

http://spectrum.ieee.org/aerospace/aviation/unsafe-at-any-airspeed/0

Edited August 18, 2011 by KursadA

[Antonov]

Te issue of wireless interference is real, but lot of it has nothing to do with that. Most airline crashes happen on takeoff and landing, and are survivable if people are alert and act quickly. What we don't want is people zoning out on their earphones or on tablets, cutting their reaction time by a few seconds that might be critical. We also don't want a hundred or so laptops, iPads, and Kindles to end up thrown about the cabin if something like an abrupt stop happens. They could go flying and hit people, or just end up in the aisle, where people can trip over them. Better to put them away for a few minutes.

[Wayne S]

It certainly is not BS. The fact that a wireless device is FCC certified does not mean that FCC tested it for all possible interactions with other devices in the vicinity; and such testing is impossible anyway. There have been many well-documented cases where the use of a PED (personal electronic device) on board has caused interference resulting in temporary disablement of important avionics.

The quotes above are from a well-known (in the electrical engineering community anyway) article from IEEE Spectrum. I suggest anyone who does not believe PED interference to be a flight safety risk to take a look:

Explain to me, what I am suposed to be looking at? All I see from that site is them showing, they had a device that picked up phones working in phone channels, which the aircraft is flying through constantly.

For it to be power cousing a glitch, sounds silly to me, the wires would need to be insulated from other wires and metal around them so they do not glitch the system. A person walking across the floor to the bathroom has a better chance of glitching the system then the power in a simple DVD player.

[KursadA]

Explain to me, what I am suposed to be looking at? All I see from that site is them showing, they had a device that picked up phones working in phone channels, which the aircraft is flying through constantly.

For it to be power cousing a glitch, sounds silly to me, the wires would need to be insulated from other wires and metal around them so they do not glitch the system. A person walking across the floor to the bathroom has a better chance of glitching the system then the power in a simple DVD player.

No, that article says much more than that: it explains why the emissions from the phones on board are strong enough to be dangerously close to the interference safety margins of the GPS receivers on board.

I notice you talk about "aircraft flying constantly through these frequencies anyway". You are aware that these EM waves are being attenuated (losing power) as they propagate through long distances, right? It is one thing to have an airplane fly through cell phone coverage areas of multiple towers, quite another to have an active transmitter merely feet, or tens of feet, away from crucial systems on the airplane. Of course there are EM waves in many frequencies all around us, but unless we're really close to the emission sources, their power is too low to cause any interference or harm. Signals in radar frequencies are all over us, but nobody in his right mind would set up a tent in front of a high powered search radar. Waves in exactly the same frequencies used by a microwave oven go through the potatoes on our pantry shelves all the time, but their energy level is thousands of times lower than those in a microwave oven. Put those potatoes in the oven though, and waves in those exact same frequencies would cook them in a very short time.

And "a person walking across the floor" does not have a chance of causing the glitch than a PED that might well have inadequate EMI shielding and stray emissions all over the place. Shielding a device against against stray RF emissions is way more complex than simply insulating the wires; otherwise we would't have so many electrical engineers just working on this in the company I work for. Anyway, I don't have the time to argue: the article is out there for people interested in the subject; and does have a good job of explaining the threat with rigorous scientific proof.

Edited August 18, 2011 by KursadA

[dmk0210]

It sounds to me like some should be ordering the FAA and FCC to compare notes.

[Jennings]

It sounds to me like some should be ordering the FAA and FCC to compare notes.

And who's going to pay for that? We've got people actively trying to get rid of the federal government by bleeding it to death.

Edited August 18, 2011 by Jennings

[ST0RM]

Personally, I think it is just a BS thing, Just like phones used at the gas pumps and used in Hospitals.

Wireless devices are controlled by the FCC who pretty much gives the frequencies a device may use, Those frequencies are passing through the aircraft all the time, satellites, radio towers etc. etc.

Frankly if one was to ask me what the true reason behind the nonsense in the air is "my guess", It might be the fact there could be others who are using the same channel, when one is in an aircraft they will jump from tower to tower, could even be a licensing deal with those who use/own said towers. I am guessing people actually make aircraft phones and want to be paid/ keep in business by "celling" them .

The old 1st gen cell phones did work that way. Now, standard cell coverage doesnt work above 10,000ft.

As was said, not every device can be tested and they are a distraction during critical phases of flight. Just like the tray table and seats. If left down and back, then block escape routes in case of emergency.

Here's a funny story on that. I once had a girl on a flight, convinced that the landing gear was connected to the tray table and seat backs. If they weren't all up, the gear stayed locked in place. Ironically we had to circle for a bit due to a T-storm over the airport. The pilot's announcement just helped my story at the right time.

-Jeff

[jester292]

Try this on for size:

Just last week I was flying a trip out of ORD, and as we were lining up on the runway we heard lots of popping and static over our headsets. A passenger behind the exit row had not turned off her phone, and although she had it on vibrate or silent or whatever, it caused broken incomming transmissions over the radio in the cockpit. We initially thought it was a radio problem, so declined the "line up and wait" orders, and passed to the other side of the runway to figure it out. One of our flight attendants caught the passenger texting.

Aaron

Edited August 18, 2011 by jester292

[Stephen]

Te issue of wireless interference is real, but lot of it has nothing to do with that. Most airline crashes happen on takeoff and landing, and are survivable if people are alert and act quickly. What we don't want is people zoning out on their earphones or on tablets, cutting their reaction time by a few seconds that might be critical. We also don't want a hundred or so laptops, iPads, and Kindles to end up thrown about the cabin if something like an abrupt stop happens. They could go flying and hit people, or just end up in the aisle, where people can trip over them. Better to put them away for a few minutes.

Speaking as a flight attendant thats pretty much the main reason.We ask for headphones to be taken off because if there is a crash the aircraft would probably lose electrical power and with it the ability to make emrgency PA's.If people can't hear what you're saying because they've got noise cancelling headphones on they might miss a critical instruction and end up injured or worse. No matter how many times you say it thereare always people who cannot seem to put their iPad/Kindle/Tablet/iPhone down for those few minutes and its almost universal irrespective of nationality or age/sex.Some of the worst offenders are frequent fliers who really ought to know better, on one occasion while on a 777 I informed a lady who was sitting in a rearward facing seat in business class that she should remove her I am a spammer....please report this post. from the shelf between her seat and her neighbours as it would likely slide off during takeoff .I was coldly ignored but proved right.The I am a spammer....please report this post. slid under the seats behind and could not be extracted by any of the crew. Our engineers had to remove four seats to retrieve it and the woman ended up missing her connecting flight.

[11bee]

Can't remember where I saw it but I recall a recent study that seemed to definitively prove that certain portable electronic devices do impact an aircraft's navigation system.

[niart17]

I guess in my mind the real question isn't whether or not the devices cause electronic problems or distractions or whatever. The real question is if you're placing your life in the hands of a couple of qualified pilots hired by an airline, and that airline tells you, "hey, please don't use your phone while we're taking off, landing or whatever because it might kill you", then why would you really seriously want to question that? What if their new reason was they have had evidence that passengers might use a cell phone to detonate some explosive? Is making that one phone call the minute you land THAT important? I agree there are some things you need to question the authorities on, but you're getting to travel a day's worth of distance in a couple of hours. I think a minor inconvenience is warranted. jmho

Bill

[Yuri]

No, that article says much more than that: it explains why the emissions from the phones on board are strong enough to be dangerously close to the interference safety margins of the GPS receivers on board.

I notice you talk about "aircraft flying constantly through these frequencies anyway". You are aware that these EM waves are being attenuated (losing power) as they propagate through long distances, right? It is one thing to have an airplane fly through cell phone coverage areas of multiple towers, quite another to have an active transmitter merely feet, or tens of feet, away from crucial systems on the airplane. Of course there are EM waves in many frequencies all around us, but unless we're really close to the emission sources, their power is too low to cause any interference or harm. Signals in radar frequencies are all over us, but nobody in his right mind would set up a tent in front of a high powered search radar. Waves in exactly the same frequencies used by a microwave oven go through the potatoes on our pantry shelves all the time, but their energy level is thousands of times lower than those in a microwave oven. Put those potatoes in the oven though, and waves in those exact same frequencies would cook them in a very short time.

And "a person walking across the floor" does not have a chance of causing the glitch than a PED that might well have inadequate EMI shielding and stray emissions all over the place. Shielding a device against against stray RF emissions is way more complex than simply insulating the wires; otherwise we would't have so many electrical engineers just working on this in the company I work for. Anyway, I don't have the time to argue: the article is out there for people interested in the subject; and does have a good job of explaining the threat with rigorous scientific proof.

I'll add a data. EM waves are attenuated by... uh... how do you say that?... by the square of the distance: if the distance doubles, the strenght doesn't become 1/2, but 1/4. You can get much more power from a cellphone that has a weak antenna but it's just a couple of inches away than from a cell tower that has a much more powerful antenna, but very far.

As others said, it's impossible to test the electromagnetic compatibility of all the stuff people take on a plane and, albeith improbable, some problems may arise. And I'd be more worried of interferences with the fly by wire than with the navigation computer!

So, as a safety measure, I think it's a right policy to ask to turn off these devices in the most crucial parts of the flight.

[Wayne S]

No, that article says much more than that: it explains why the emissions from the phones on board are strong enough to be dangerously close to the interference safety margins of the GPS receivers on board.

Then show me what I am supposed to be looking at other then them picking up the channels the phones are using. I have now read the entire thing 3 times and still come up with the same conclusion.

I am guessing to find out what you are trying to direct me to, it is better to understand what way you think a phone can mess up the GPS system?

Not to sound like an arse with this statement "tho words like (scientific proof) annoy the crap out of me" .

the article is out there for people interested in the subject; and does have a good job of explaining the threat with rigorous scientific proof.

There is more "rigorous scientific proof" that Bigfoot is real then this stuff.

Edited August 19, 2011 by Wayne S

[Wayne S]

Try this on for size:

Just last week I was flying a trip out of ORD, and as we were lining up on the runway we heard lots of popping and static over our headsets. A passenger behind the exit row had not turned off her phone, and although she had it on vibrate or silent or whatever, it caused broken incomming transmissions over the radio in the cockpit. We initially thought it was a radio problem, so declined the "line up and wait" orders, and passed to the other side of the runway to figure it out. One of our flight attendants caught the passenger texting.

Aaron

Aaron if what you say is true, "noise/static" I would speculate it happened from heat possibly in the circuitry not the phone. There is not enough power there to do that. Put it this way, the phone is not like motors running in a car or ignition that we might hear as static through a car radio, I would think most phones have the frequencies so close together, the phone would not even work, if it could do things that you mention.

Edited August 19, 2011 by Wayne S

[niart17]

"In one telling incident, a flight crew stated that a 30-degree navigation error was immediately corrected after a passenger turned off a DVD player and that the error reoccurred when the curious crew asked the passenger to switch the player on again. Game electronics and laptops were the culprits in other reports in which the crew verified in the same way that a particular PED caused erratic navigation indications."

I would think this part of the article that was linked too kind of suggest that maybe there is something to the theory of interference. I don't think it's too unreasonable for an airline to ask someone the not use a phone even if the chance of it causing problems was only less 10%. That's more of a chance than I'd want to take with my own life much less a plane full of other's lives as well.

Bill

[jester292]

Hasty reply, my apologies. Edited because of initial lack of maturity!

Aaron

Edited August 19, 2011 by jester292

[Scooby]

Personally, I think it is just a BS thing, Just like phones used at the gas pumps and used in Hospitals.

Wireless devices are controlled by the FCC who pretty much gives the frequencies a device may use, Those frequencies are passing through the aircraft all the time, satellites, radio towers etc. etc.

I worked with Electronic Warfare and based on this knowledge and training in the airforce and I can tell you that electronic device emmisions can cause problems.

In my new employment as a Biomedical Engineer I was able to do a series of tests in a hospital. One of the most notable tests I carried out was with security hand-held motorolla walkie-talkies. Everytime they transmitted within 150ft of an infusion pump they kicked off the pumps. These pumps are hooked up to patients and control the flow of IV fluids to their bodies.

Rules are there for a reason.

[Aaronw]

I'm just wondering if these handheld devices can cause so much interference to throw off aircraft navigation / communications then why are they allowed to be turned on after take off? A 30 degree error caused by a DVD player seems pretty significant in flight more so than take off.