“Please turn off all electronic devices” - Why?
I am a frequent business traveler. I fly at least once a week and often times I’ll have three or four flights in a week. That adds up to eight times per week that I get hassled by a flight attendant to turn off my iPod. Sometimes I leave it on, and lo-and-behold the plane somehow manages to land. I always had my doubts about the technical merits of this request, so I decided to ask an embedded systems engineer about it. This is a guy who has to build the guts of electronic devices, so I consider him an expert on the topic.
According to him, the request has no technical merit whatsoever. Here’s the deal. When electronic devices are built, they go through what is called an emissions test. In order to get that FCC stamp, they must pass a test showing that they will not interfere with other electronic devices. Your iPod has this stamp. So the concern that your gadget will somehow “mess” with the plane’s systems is unfounded.
Secondly, all electronics (including the ones in the cockpit) have to pass an immunity test. This is a test designed to account for those rogue devices that don’t pass the emissions test. This means that the device will work even if there are other devices “messing” with its signal. So unless the planes are using technology that doesn’t pass the immunity test … we should be safe.
The engineer (who wished to remain anonymous) made one final point that really drives the message home:
Why don’t we make people turn off their pace makers? Or their watches?
I finished the interview asking about special cases. What about TVs or other devices that transmit or receive signals? Again, they shouldn’t matter because of the immunity and emissions tests, but also remember that television broadcast signals are everywhere. Turning off your pocket-TV won’t change that fact. The plane will be getting bombarded with those same signals anyway.
Here is another interesting article on the topic: http://www.airspacemag.com/need-to-know/16046567.html
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Like I wrote...
May 5th, 2008 at 8:34 pm
Well, it’s a fine question and the hassle is annoying. Though for the sake of discussion, I’ve seen a lot of cell phones that consistently mess with landline telephones, computer speakers, and sound reinforcement sytems (you know, that loud buzzing-clunking noise… AT&T phones are particularly susceptible).
Playing devils advocate, I don’t know, it might be worth the precaution. One blackberry buzzing on a conference call is annoying, but on a plane with 400 passengers, each with a cell phone and the outside potential to interfere with the pilot’s communication systems, I wonder if it might not just be a good idea to have us turn them off during approach.
May 5th, 2008 at 9:39 pm
Yah, I think there is a lot of anecdotal evidence like this. I’m hoping the wisdom of the crowd can weigh in on this one to sort it all out.
May 6th, 2008 at 6:45 am
I think it’s hokey, too. Some planes are offering in-flight cell phone service now. Maybe we’ll see it soon.
http://www.msnbc.msn.com/id/24355296/
May 6th, 2008 at 7:50 am
I may have to shoot myself on the plane if I am stuck sitting next to some idiot on a conference call. Unfortunately people are not always born with manners and it is the airlines job to step in and enforce them to ensure everyone has a nice trip. I would hate to see cell phones allowed on planes.
You think crying babies are bad, what about cocky businessmen and teenagers!
May 6th, 2008 at 8:40 am
There’s a huge difference between turning off electronics like phones to prevent people from being annoying versus safety. I think that we’d all agree that if turning off these devices would help keep us safer then we’d happily do it. But the airline industry doesn’t have much credibility these days. Telling the truth seems to be pretty difficult for many. It is a pretty sad statement, but I am actually surprised when a flight attendant or pilot is candid with us (their customers) when they’re telling us about a flight delay etc. But if they can’t tell us the truth about when our flight will actually depart then how can we trust them to tell us the truth about using electronics?
May 6th, 2008 at 8:51 pm
Do you really think you could carry a device on a plane if it was that dangerous? I’m pretty sure the truth is they don’t want to deal with the noise.
May 8th, 2008 at 1:28 am
I suspect that the airlines will find it a lot more difficult to get people to shut off their phones if they don’t use the safety threat.
Imagine having a plane load of people yakking away throughout a flight! Should be enough to drive a lot of the saner passengers insane.
May 16th, 2008 at 1:12 pm
I am a Computer/Electrical Engineer myself and have friends who worked in the Wireless/Telecom industry… On such friend who does research on wireless cell networks etc. told me the real reason behind why Airline industry asks passengers to turn off their phones. It has nothing to do with interference with airplane navigation… in fact, it is done to keep airplanes loaded with “on” cell phones from taking down surrounding cell-towers and wireless infrastructure down. Our phones “register” with the nearest towers to let the phone companies know where the phone is and which tower will receive/send call to that phone. As we travel around in our car, we are sometimes “handed off” from one tower to another tower, even during a phone call. Now think about an airplane loaded with 200 phone, multiply that times 5-10 airplane taking off/minute around, larger airports, compare speed of an airplane vs car, imagine thousands of phones trying to do the “hand-off” from cell tower to another during take-off and landing (when they are “in-range” of towers) and you have makings of being able to cause havoc on cell-phone companies’ infrastructure - given that cell phone towers are only few miles apart, plane load of phone going across them every few seconds is too much for the cell-companies to handle - now you know the real reason you can have cell-phones on during take-off/landing
August 15th, 2008 at 10:16 am
That still doesn’t explain why the Airlines tell you to turn off your phone. You just told what happens with the calls being handed off. I think that “Matt @ Corporate Hack” has the most accurate answer about the interference. Also i think they tell you to turn them off for safety purposes. When the plan is landing and taking off that is the most crucial time of the flight. So if they have to give safety instructions. They don’t want to be liable for some idiot listing to their IPOD all the way up and not hearing the instructions. I understand the phone concern just not the mp3 player, dvd player, or laptop with the wifi off. My main concern is the idiot that forgot to turn there cell phone off or is doing it because they don’t see any reason in it. It is a possible hazard to the flight. I really think people just need not wine about having to shut them off and just do it. Is it really that big of a deal to shut off you phone for the flight. you can’t use it anyway you are out of range of the towers. Also is it that big of a deal to not listen to you music for the first 5 minutes of the flight and the last 15 of it.