Flight regulation: Airplane mode in Mobiles now OK? - Uh? - Page 1
Forum section: electronics / general

author: Zucca
author_rank: Unknown
timestamp: January 28, 2015, 10:38:45 am
content: I'm not an expert, so here my point of view.I flew this week end and yes the phone airplane mode could be finally used in order to reduce the EMI.I saw that function in my Nokia back in the 2007, but the phones need to be completely off in a plane until recently.Now, have the flight companies replaced the coax cables with high quality triax ones or it is/was just an overkilling requirement? Did maybe the phone companies changed the circuits spec.?BTW, Have you ever heard of a plance crash or problem due to a not turned off electronic device?Yes I believe the fear of a airplane disaster can influence a lot the technical judgment/reality. I imagine everybody shitting in their pants and not taking the responsibility.After googling 5 min I also understood that EMI was not even the first concern, they wanted to avoid hard flying objects in the cabine. So theoretically also an heavy book was a risk.

author: nowlan
author_rank: Frequent Contributor
timestamp: January 28, 2015, 10:47:52 am
content: I flew last week, and asked everyone to turn off during take off / landing.My understanding is that is to keep people from being distracted during the safety speech etc.I believe the FCC called them out on the bullshit about interference. If it has an fcc approval it shouldnt interfere with other systems.Although your point about projectile objects sounds like good advice too.

author: Zucca
author_rank: Unknown
timestamp: January 28, 2015, 10:59:26 am
content: Quote from: nowlan on January 28, 2015, 10:47:52 ammaybe it depends on the airplane model? bah...

author: tom66
author_rank: Super Contributor
timestamp: January 28, 2015, 11:24:23 am
content: The truth of the matter is that thousands of people use their phones on a flight with the cell radio and WiFi on irrespective of what flight attendants say, and nothing bad has happened as a result.

author: IO390
author_rank: Regular Contributor
timestamp: January 28, 2015, 02:44:29 pm
content: EMI from phones etc has basically NEVER been a problem on any passenger-carrying aircraft built in the last 40 years. The only thing that has supposedly happened once is some laptop causing something to stop working on some Boeing (not sure what model). Boeing then conducted a flight with the same plane and the same laptop and couldn't replicate it. But that's the only thing I've heard of.I've done a lot of work on avionics and although some of the gear used is jaw-droppingly shoddy, it's either well shielded or too simple/crap for a phone to interfere with it.It's just to get you to use the satellite phones in the arm rests. Of course, you can't get GSM signal at 30k ft+, but I imagine that some marketing guy somewhere who has no idea how things work decided that people couldn't use their own phones for the above reason.There's no way that flight attendants can check to make sure that everyone's camera is off and that all the phones are on flight mode, and given that most people also now know it's all bullshit, the airlines probably thought screw it and dropped the rules.

author: Howardlong
author_rank: Super Contributor
timestamp: January 28, 2015, 04:08:10 pm
content: Speaking as both a pilot and an RF engineer, including fixing avionics, there is indeed little correlation between PEDs and avionics or other failures.What confuses things is that rules differ between carriers, and aircraft types on the same carrier. Bear in mind that it is also the national regulatory authorities of an aircraft's registration that goes a long way to determining what you can and cannot do, hence the disparity, i.e., the FAA != CAA etc.What I can tell you that if you leave your phone on in many cockpits you'll often hear that irritating clickety click going through your headset, so if you think all avionics must be EMI compliant you're wrong! Keep in mind that an awful lot of avionics in current use was designed before cell phones and PEDs existed, so were not unit tested against the kind of emissions that they make.Just keep in mind that it's not just the EMI aspects. For example, many carriers allow you to use your tablet but not laptop during the takeoff and landing phases. The reason for this is simple, for just the same reason as you have to stow everything during these phases, i.e., do you want a brick in your face in the event of a sporty landing?I'll also add that under international aviation law, everyone on a plane must obey any lawful request from the captain, whether or not you think it's right or wrong, it's not for you to make that decision. That might include being asked to switch your phone off, or else you might enjoy some restraint and a pair of cuffs upon arrival, not necessarily at your intended destination.If you really want to use your phone for making voice calls at 40,000', may I suggest that you take a walk to the galley rather than piss off your fellow passengers with an unnecessarily loud "I'm on the plane" conversation in the middle of the night!But yes, in general the regulatory authorities have been erring on the side of caution.

author: G7PSK
author_rank: Super Contributor
timestamp: January 28, 2015, 04:27:07 pm
content: I have heard two different reasons why phone usage was not allowed. The first one was that if you used a cell phone in an airplane at altitude it would see too many cells and cause the system to crash, this I heard from a Vodafone engineer in the early 1990's. The second more recently from the Captain of a British Airways plane was they or he did want people going down the steps of the plane and dropping a phone onto the runway amidst all the kerosene fumes still hanging around, that sound reasonable to me and now most embarkation/disembarkation is done with enclosed walkways the fume ignition risk is reduced and would explain the admonition that used to be given about not turning your phone back on until you were in the airport buildings.

author: richard.cs
author_rank: Super Contributor
timestamp: January 28, 2015, 04:34:09 pm
content: The exact nature of "flight mode" isn't consistant between devices either. They all turn the mobile comms and the wifi (and bluetooth?) off, but beyond that it seems to be pot luck. Some but not all allow FM and GPS receivers to stay on, and these may actually be more of a problem than the things designed to transmit. Many broadcast FM receivers use a 10.7 MHz IF and high-side LO putting the local oscillator in the middle of the VHF air band and despite the fact it's not intended to radiate enough can leak to cause a problem, typically you might blat out a channel and be an annoyance. This is actually the reason why broadcast FM in the UK never used to go up to the 108MHz it now does. A similar LO-leakage problem exists with GPS receivers, better because of the antenna locations but worse because of the signal strengths.Mobile phone networks don't appreciate terminals moving at high speed, nor those at sufficient altitude to see several towers on the same channel at once. The latter just reduces the number of channels availiable by looking like in-band interference to the towers it's not connected to, the former causes problems with handovers. It is possible to cause nasty effects on the network by trying to make a call on a plane, particularly if multiple people do it. They weren't designed to do the handovers between towers that fast and barely manage passengers on trains - until a whole load of new fibre was laid there was a problem with calls always dropping near London Waterloo because the data link between adjacent cells wasn't sufficient to handover all the passengers in the time availiable.I can certainly believe that if people routinely made calls from aircraft it would cause annoying problems with dropped calls on the ground. It's only applicable during take off and landing normally as the tower beam patterns are too well controlled to waste much energy upwards.

author: nixfu
author_rank: Unknown
timestamp: January 28, 2015, 05:21:09 pm
content: I work for an airline.In the jumpseat positions, we have 110V outlets to plug in our electronics/laptops whatever and we can use them from the time we sit down until we get off the plane as long as the captain says its ok.Been that way for years actually. Only the sheep in the commercial seats have had those restrictions.The rules were on commercial travelers never for technical reasons, they were strictly for crowd control reasons.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: January 28, 2015, 06:37:33 pm
content: I fly quite regularly, and never turned off my iPad or iPhone completely. I did activate flight mode of course, just to be safe, but I couldn't be bothered to actually go and switch the thing off.Almost every single flight I've been on had young girls shooting videos of the takeoff or landing with their phones through the window.Nobody ever called us out on it. It's just one of those weird paranoid flight rules. It's not rational, and apparently not taken seriously by the staff either.

author: Unknown
author_rank: Unknown
timestamp: January 28, 2015, 08:20:54 pm
content: I can honestly stick my hand up and say that I have never, ever turned my phone off during a flight (or placed it in flight mode). I do however place it on silent as to not disturb other travelers and make sure it's put away during the safety brief.I figure what's good enough for pilots is good enough for me. Back in the days of GSM handsets you'd often hear the sound of a GSM phone re-registering over the VHF radio channels when the pilots were coming in on approach. On small aircraft, pilots even have a 'car kit' style dock for their phones installed in the aircraft itself.If it were a serious safety issue, mobile phones would be banned from the cabin altogether.There is also the "it causes issues for cell towers on the ground" argument. I had a conversation with an engineer from Telstra years ago who explained that the gear for each cell is pretty resilient (and getting better all the time). If for some reason the handset hops too quickly, the call is simply dropped without causing issues to the rest of the network. Likewise, firmware in the handset itself will 'give up' after a certain number of unsuccessful attempts to register to a network and retry at a set interval. It won't endlessly keep transmitting 'just because' towers are in-range.I'd say the rationale behind the entire ban (largely) is because people are stupid. Many can barely pay attention crossing the road or walking down a footpath without being distracted by Facebook or Snapchat.

author: AG6QR
author_rank: Frequent Contributor
timestamp: January 28, 2015, 09:20:00 pm
content: Quote from: nixfu on January 28, 2015, 05:21:09 pmTrue, but if you're right there in the jumpseat, the pilot can say, "Hey, the VOR is acting a little wonky. Can you shut off that laptop for a minute to see if it clears up?" It's a lot harder to do that with all the passengers in the back.But yeah, I generally agree that the authorities have been acting out of an overabundance of caution. I suspect most flights over the past decade, or clearly a significant portion of them, have at least a few cell phones left fully on (not airplane mode). If this were a serious risk, we would have seen consequences by now.

author: Psi
author_rank: Super Contributor
timestamp: January 28, 2015, 09:40:37 pm
content: Quote from: zucca on January 28, 2015, 10:38:45 amThe thing that happened recently was the industry relaxed the rules and allowed airlines to permit people to use phone during takeoff/landing (with flight mode on).From an industry standpoint you have always been able to use your phone during the actual flight with flight mode on.Of cause, there were a few airlines that chose to ban phones entirety but that was there choice.

author: Zucca
author_rank: Unknown
timestamp: January 28, 2015, 10:01:44 pm
content: LOL, what an obscure story.Still remember that German on my right in a plane that day:"Turn it off immediatey!" looking at me with a very scared face.

author: MiataMuc
author_rank: Regular Contributor
timestamp: January 31, 2015, 09:24:37 am
content: Well this reminds me on the ban on mobile phones in hospitals. When mobile phones first came to market they banned the use in the whole hospital; the main reason for it was that they all had invested in quite expensive telephone systems for their patients (with hefty tolls..). Hotels on the other side were very envious, because they did not find a reason to ban mobiles..

author: EEVblog
author_rank: Unknown
timestamp: January 31, 2015, 10:09:51 am
content: I turn mine off during flights, for the simple technical reason of saving battery life. I know I'm not going to use it, so having it pissing away battery when I might need that battery at the other end is just silly.

author: tszaboo
author_rank: Super Contributor
timestamp: January 31, 2015, 10:45:31 am
content: One of the reasons could be, when the plane is ascending, and you leave the mobile tower coverage, all the phones start increasing the transmit power, up to some 0,5W - 2W, searching for service. Multiply this with the 250 phones in a big plane, even though they only transmit 1/8th of the time, we are talking about 60W or RF put into an enclosed metal can, for no good reason. So that is why flight mode is there.They ask you to turn off during takeoff/landing purely because that is the most dangerous part of the flight, and they make everything to increase your chance of survival in case of an accident. That is also, why they dim the lights, your eyes react better if it is dark outside. Imagine, you cannot exit the plane, because some moron decided to make a video of the crash instead of running for it.