Take the 2-minute tour ×
Aviation Stack Exchange is a question and answer site for aircraft pilots, mechanics, and enthusiasts. It's 100% free, no registration required.

What problems do cell phones cause? How is using a cell phone in the air different than using it from the ground?

share|improve this question
    
This question covers cellular data, but the answers apply equally to cell phones. –  Lnafziger Mar 3 '14 at 0:49
    
Great question! –  Rob Mar 3 '14 at 7:53
2  
...and sadly, one of the few remaining places where it's possible to be surrounded by strangers not yacking into their phones seems to be heading for extinction. –  Simon Mar 4 '14 at 22:50
    
@Simon Dude! we are living in the 2010's! This is the decade of txting! Actually, I find the lack of people yacking and the increase of people texting, often in the same room, even at the same table disturbing. –  flyingfisch Mar 5 '14 at 1:34
1  
Ground station for cell hone are designed to communicate with a phone that is not too high (let's say few tenth of meters abouve the ground). If the cell device is higher, base station cannot reach it (a base station emit mainly horizontally) –  Manu H Oct 3 '14 at 15:15

7 Answers 7

up vote 12 down vote accepted

Why aren't cell phones allowed?/ What problems to cell phones cause?

Most of these cases apparently originate from a series of unexplained events in the 90s which were believe to be caused by electronic gadgets, hence the ban. This was when cell phones appeared, and there was an aggressive ban as a result. NASA has a list which includes some of these and makes for an interesting read.

Now however an increasing list of airlines is allowing them again, depending on jurisdiction. FAA is working on allowing it from a regulatory standpoint. Bear in mind that phones were probably much more powerful back when these rules were introduced.

Mythbuster (episode 6, 2006) did a test on this by sticking in a powerful transmitter into a business jet. Their website gives a slightly different version: It was the FCC, not the FAA, who led the way for this regulation:

Explanation: Never mind what the chatterbox in the seat next to you says about cell phones messing with plane navigation — those metallic birds are built airtight against foreign signals and operate on entirely different frequencies than cell phones.

So why all the fuss about phones? When you make a call at 10,000 feet, the signal bounces off multiple available cell towers, rather than one at a time. That means too many phone-happy jetsetters might clog up the networks on the ground, which is why the Federal Communications Commission (FCC) — not the Federal Aviation Administration (FAA) — banned cell use on planes.

How is using a cell phone in the air different than using it from the ground?

Is it sensible to allow them on aircraft? To quote one of the above sources:

although the FAA recommends that you still switch to airplane mode because you’re not going to get a signal 30,000 feet in the air — the only hit you’ll take is a dead battery when you land.

So it's probably not a huge loss if you're flying commercial aircraft at 10,000 meters. In any case, you can't expect a service like you do on the ground, unless like Lnafziger says that the aircraft is equipped with a cellular basestation called a Picocell, illustrated below:

picocell

share|improve this answer
    
Is it against FAA regulations to use a cell phone while in the air? –  flyingfisch Mar 3 '14 at 0:28
2  
@flyingfisch wired.com/autopia/2013/10/faa-ban-lifted –  MikeFoxtrot Mar 3 '14 at 0:35
3  
Note that where it is allowed, They are using special equipment on board the aircraft (picocells) in order to solve the issues that you mention here. They don't just suddenly allow the use where they didn't before for no reason. –  Lnafziger Mar 3 '14 at 0:53
    
@Lnafziger ah, thanks for clarifying. :) –  flyingfisch Mar 3 '14 at 1:30
1  
The ban on cell phones has nothing whatsoever to do with potential interference with the aircraft, at least not in the U.S. The former ban on use of any personal electronic device during critical flight phases (taxi, takeoff, and landing) was due to that reason, but that ban has been lifted. To answer flyingfisch's question, no, it is not against FAA regulations to use a cell phone while in the air. It is, however, against FCC regulations due to interference with the cell network, not the aircraft, as the quote in this answer from the Mythbusters website correctly points out. –  reirab May 15 '14 at 20:33

Apart from Manfred's answer, there are other factors in play:

  • Airlines make quite a nice income from the payphones in aircraft
  • Cellphone towers typically have pretty bad (if any) reception straight up, they're designed for ground level use after all which dictates the design of their antennae (an omnidirectional one is a lot less energy efficient)
  • People in border regions already complain about being hit by roaming charges when they set their phones to automatically switch networks. In an aircraft that'd be multiplied as those foreign towers might be in range from further inside a nation's borders (but see previous point as to why maybe not).
  • keeping a quiet cabin. As hinted, 150+ passengers all yacking away on their cellphones (and most people tend to shout into the darn things) make one hell of a racket. Bad marketing for the airline. Everyone wants every other passenger to be quiet and behave but want for themselves the right to do whatever they want, other passengers be darned.
share|improve this answer
2  
@mins no, the alarmists still have to prove it's NOT safe. There's no way to ever prove there's no risk whatsoever, nor should you have to. –  jwenting Jan 4 at 6:38
1  
@mins 'Alarmist' is accurate in this situation. RF transmissions are not ionizing radiation. Additionally, assuming each of the flight crew members has their own personal cell phone (this seems like a reasonable assumption nowadays,) they would be getting far more total microwave radiation from occasional use of their own phone than they would from people on board, even if everyone were using their phone for the entire flight every time. This is because received power follows an inverse square law. Power decreases in proportion to the square of distance from the transmitter. –  reirab Jan 8 at 14:29
1  
@mins Flight crews do have real radiation concerns, but cell phones aren't one of them. –  reirab Jan 8 at 14:36
1  
@mins According to the American Cancer Society most such studies have found no link. Only a rather small minority of studies have suggested any link. As far as the comparison to microwave ovens, that's an apples-to-oranges comparison. Those things emit around 1,000 W. A cell phone connected to an on-board picocell is likely to be a few mW at most, perhaps less. Also, an aircraft cabin is a bit larger than a microwave oven. –  reirab Jan 8 at 19:33

I am a private pilot, and sometimes, the cellphones cause interference with the radio. Most of the time, cellphones are not a problem, but once in a while, I have to turn mine off because it is causing parasitic noises on the radio.

I don't know how bad it would actually be in a passenger aircraft. But if it is similar to my experience in small aircraft, then it would be easier to just ban cellphones, rather than have a little light (like the seatbelt light) indicating when you can or can't use your phone.

share|improve this answer

Cell networks require that cell towers be able to distinguish between signals coming from phones which are within the zones served by the towers, and those coming from phones in more distant zones. There are nowhere near enough radio frequencies or time slices to allow every zone in the US to have its own combination of frequency and time slice. In general, however, since the amount of signal received from a phone that's transmitting at a particular power level will drop off proportional to the square of distance, arranging zones so that the closest phone outside of a zone that will use a particular frequency/time-slice combination will never be less than be 3 times as far away as the furthest phone within the zone will generally make it possible for towers to receive the signals from phones within their service zones without too much interference from phones in other zones.

If a plane which is on a plane, 30,000 feet above the surface, transmits a signal which is loud enough to be heard by a tower serving a zone directly below, that same signal is likely to be received almost as well by towers for quite a ways around, some of which might have been expecting to use the same frequency and time slice to serve their own zones. A cell network might be able to recognize the situation and assign frequencies and time slices in such a way as to avoid interference, but a single phone call from a plane might tie up ground-level bandwidth resources in multiple zones which, but for that call from the air, could each have used those resources to handle a separate call.

share|improve this answer
1  
Welcome at Aviation.SE supercat. Interesting post. So you reckon the reason for disallowing cell phones on aircraft is to protect the cell network? –  DeltaLima Oct 13 '14 at 18:33
1  
@DeltaLima: The FAA restricted them for fear of interference with airplane systems; the FCC because of interference with cellular networks. –  supercat Oct 13 '14 at 18:36
    
Great clarification. Just adding that in case cell phones are authorized in planes, then a local base transceiver station (BTS) will be embedded on board and will be connected to a communication satellite. Planes are too fast for cell phones or BTS to maintain a link with a ground network (doppler shift and cell size), signal is attenuated by the cabin at best, and completely interrupted in most of the cases. –  mins Jan 4 at 1:23
1  
@DeltaLima Yes, the FCC banned them for this reason. Someone can correct me if I'm wrong, but I don't think the FAA ever actually had a ban specifically against cell phone use on board. They did have a ban on use of any electronic device during critical flight phases, but that was removed in 2013. The FCC ban remains, though, IIRC, they are studying removing it. Having said that, if they remove their ban, the DoT has said it may place its own ban on voice calls for the simple reason that passengers don't like listening to each other's phone conversations for hours on end. –  reirab Jan 8 at 14:43
    
@reirab: While some passengers may find phone usage annoying, others may value the ability to conduct business during what would otherwise be idle time. Unlike smoke from the back of the plane which could end up circulating throughout the aircraft, chatty people in the back of the plane should not affect those elsewhere. I would think the optimal solution would be for airlines to ask passengers whether they wish to use their phones, whether they wish quiet, or whether they don't care (perhaps offering free headsets, an extra snack, or some other perk to people who opt for the latter choice). –  supercat Jan 12 at 17:01

What problems do cell-phones cause?

The FAA believes they could cause controlled flight into terrain.

Airlines have been ordered to replace or modify the cockpit display units fitted to hundreds of Boeing jets.

The US air safety regulator said that tests had indicated that mobile phone and computer signals could cause the screens to go blank.

...

"We are issuing this AD [airworthiness directive] to prevent loss of flight-critical information displayed to the flight crew during a critical phase of flight, such as an approach or take-off, which could result in loss of airplane control at an altitude insufficient for recovery, or controlled flight into terrain," it said.

From BBC

share|improve this answer
1  
The use of cellular telephone radios remains banned on board aircraft in the U.S. It's banned by the FCC, though, not the FAA. The reason is that they (at least used to) wreak havoc on the cell network. The FCC is considering removing this rule, since it's largely outdated, but the DoT is considering placing its own ban on in-flight voice calls because most passengers have indicated that they don't want to hear people talking on the phone for several hours on end. Delta, for instance, has stated that they will continue to ban voice calls regardless of government regulations. –  reirab Oct 3 '14 at 14:39

I am not myself a pilot, but I have a number of friends that pilot small private aircraft and use cellphones while in flight. At altitudes of 10 or 12 thousand feet and speeds of 150 kph they work just fine.

People say they might 'interfere' with the aircraft. But if the electronics in aircraft are really so susceptible to interference, why are you allowed to use cell phones in the airport?

share|improve this answer
1  
Being a few inches or feet from the electronics is quite different from being a mile from them. Signal strength degrades with respect to the square of the distance from the transmitter, so a cell phone being used on board the plane would provide several orders of magnitude more interference to electronics on board than a cell phone being used in the terminal. –  reirab Sep 24 '14 at 17:57

if we use a cellphone in an aeroplane it might disturb connection between the controlroom and plane and also between radar. which will be dangerous that it makes unable to connect the control room for an emergency.

i think this is the reason that cellphones are not allowed to use in planes

share|improve this answer
    
no, that's the stated reason. But it's hard to believe that the systems are that sensitive as it'd mean a terrorist could bring down an airliner by putting a working cellphone in his bag, put it in the overhead bin, and have someone call him while in the air... –  jwenting Mar 12 '14 at 13:45
    
@jwenting Actually, it's not even the stated reason. The stated reason is that hundred of thousands or millions of cell phones broadcasting at full power with each of them in line-of-sight to thousands of cell towers at any given point and moving at 600 mph at least used to wreak havoc on the cell network. It's banned by the FCC, not the FAA. However, it's my understanding that it doesn't matter as much to the current cell network, which is why the FCC is considering abolishing the rule. –  reirab Sep 24 '14 at 18:03
1  
However, even if the FCC gets rid of its rule, the DoT is considering banning the use of cell phones on board in order to keep passengers from beating up other passengers that are talking loudly and incessantly on their phones while others are trying to sleep. Studies have continually shown that most passengers want talking on phones in flight to continue to be banned. Delta has stated that, even if the FCC ban is lifted, it will continue to disallow voice calls due to customer and crew feedback. –  reirab Sep 24 '14 at 18:08

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.