Phones on planes

Factual Questions
1

Somewhat similar thread from 2007

The rules about using cellphones on a plane don’t make a lot of sense, and what just wondering what the straight dope is. Before anyone gets the wrong impression, I wouldn’t complain about this, or anything else, during a flight. But it doesn’t make sense, for at least these reasons:

  1. All phones have a flight mode that shuts off all tx send and receive. However, most airlines, IME, state in their safety video that phones cannot be used, even in flight mode.
    So what’s the point of it? Was there some kind of deal the FAA and phone companies failed to tie up, and this is the legacy of that?

  2. If there really is a safety issue with having phones switched on on a plane, then FFS we need to investigate that as a matter of urgency and fit planes with cellphone scanners or something. Because I’ll bet most flights now carry at least a dozen phones left on by mistake, whether in the hold or the cabin.

  3. Usually there is no issue with using a tablet on a flight.
    But there isn’t any real distinction between tablets and phones now, other than screen size (and there’s overlap even there). You can put a sim card (or in fact two) in my tablet and use it as a massive cellphone for example.

2

As I understand it there are two main reasons why they are not allowed. One is that phones with no network keep looking for one, and that interferes with the pilots radio - you can sometimes get the same problem in a car. The second one is social acceptability. We have all suffered from the idiot on the train who shouts down his phone; sometime with information we would rather not hear - imagine that on a plane where the reception might well be pretty marginal.

Some airlines offer wifi these days, so email and tweet is possible.

3

My WAG is that it’s easier to just ban them than to check/enforce that everyone who’s using one has it in “airplane mode.” But I’d be interested to get the Straight Dope.

4

You’re confused about #1.

You absolutely may use your smartphone in flight mode as a computer, gameboy, etc. That’s what flight mode is for. They’re trying to say you can’t use it to make phone calls. As a separate matter passengers are required to put away large electronics during taxi-out, takeoff, landing, and taxi-in. Phones aren’t large, tablets are mostly not large, but laptops are.

Each carrier is free to adjust how they try to explain this arcana in 3 sentences or less without sounding too much like the IRS. I can’t say that any airline much less every airline succeeds at this.

#2: Yeah. There have been, and continue to be, occasional and unpredictable issues.

The origin of all this is that under FAA, absolutely everything is totally prohibited until it’s proven by rigorous engineering testing be 99.999% safe. Then the prohibition can be relaxed. But *only *insofar as it’s been explicitly tested to that level. That would mean testing each model and revision of cellphone and tablet against each model of aircraft and each variant of the avionics.

Clearly that has exactly zero to do with how the consumer electronics industry works or how public expectations have evolved in the last decade-ish.

Under intense public & airline pressure the FAA threw up their hands and punted this one. Fortunately at the same time devices have been moving to frequency bands that affect traditional aircraft avionics less, and at the same time avionics are being designed with more armoring against RFI.

But “stuff” still happens. As examples:

Right now we have just gotten approval to use the on-board WiFi with our iPads in the cockpit. This way we can connect to official weather sources and see the same real time weather picture you all have been enjoying from weather.com for the last few years.

Except on one model of aircraft where every few hours using WiFi in the cockpit causes a random crash-and-reboot of the cockpit screens that show all our instruments. Oops. There’s a fix in the works to up-armor whatever gizmo occasionally goes berserk when exposed to the iPad transmitting on WiFi from a couple feet away.

Fortunately this was discovered during many hours of very boring testing aboard a parked but fully powered-up aircraft.

So yes, RFI can be an actual problem; not just a theoretical one.

As a separate matter, when we need to make an autoland into really crappy conditions we’re required to make a special PA announcing an absolute prohibition on any device being turned on. On but in airplane mode isn’t good enough; it has to be O-F-F off. And the FAs are required to go through the cabin looking for everybody trying to hide the fact they’re still playing with their toy.

I don’t know whether this is my carrier’s own idea or is forced by the FAA. I do know it’s in our official FAA-approved rulebook which makes it carry the force of law regardless of who thought of the idea.

5

Flights I’ve been on in the last few years have announced that devices must be in flight mode, and can be used any time except during take-off and landing.

6

It’s been a while since I’ve flown anywhere, but it used to be that most airlines would prohibit phone use during takeoff and landing, but would allow phones to be used in flight mode while the plane was airborne.

Also, the airlines didn’t make a distinction between phones and tablets, and just said to turn off all electronic devices during takeoff and landing. Once we were airborne, they would announce that electronic devices could be used, and if it was something like a cell phone or a tablet that it could only be used in airplane mode.

There is a bit of a safety issue, but it’s complicated. First of all, cell phone users are generally stubbornly stupid. It often seems like the best way to get someone to use a cell phone in a particular area is to stick a sign there saying that their use in that area was prohibited. When the public has this vague idea that cell phones can crash the plane, they go ahead and use their cell phones on the plane anyway. So everyone has just had to cope.

Cell phones can interfere with plane communications (i.e. the pilots talking to the tower) and can interfere with the plane’s instruments. I know of one case (prior to 9/11) where a cell phone user completely prevented the pilots from talking to the control tower, but this was over in Europe somewhere. The cell phone user refused to hang up and was arrested upon landing. It’s much more common that the cell phone just causes annoying noise in the pilot’s headsets. Cell phones can also make the compass go wonky and things like that. I’ve talked to a few pilots though, and they mostly say that pilots aren’t idiots. If the compass suddenly turns 90 degrees and the plane hasn’t changed direction, the pilot isn’t going to stupidly follow the compass and fly the plane into a mountain side. Pilots have multiple instruments, and can handle it if one of them starts misbehaving. Similarly, if they do have trouble communicating with the tower, they just ask the tower to repeat what they said. Still, it’s a bit of a safety issue as it’s kinda similar to driving a car while your kids are arguing in the back seat. Yeah, you’re probably not going to crash the car over it, but still you’d like to avoid it if possible.

Plane manufacturers have also gotten good at protecting the plane’s systems from cell phone interference. The electronic shielding on modern airliners is pretty darn good. The wonky instruments is mostly something you see on older and smaller planes, like your typical single-engine Cessna.

The controls for many airliners are also hydraulic. Those systems aren’t affected by cell phone interference. What concerns me is that a lot of the newer planes are fly-by-wire, and while those are intentionally hardened against cell phone interference, you can’t possibly test every single cell phone type against every possible location and use throughout the aircraft. So for engineers like me, the most we can say is that a cell phone possibly interfering with the flight controls may not be likely, but it isn’t completely impossible. There’s no practical way to test to prove that it cannot happen. This makes some people (like me) a bit nervous about fly-by-wire planes.

Some of the cell phone regulations come from the FCC as well. Cell phones in the early days used to wreak havoc on cell phone systems when used in a plane, because not only could the phone reach multiple towers, but the phone could also reach multiple systems simultaneously. This was something that the systems hadn’t been designed to handle, and it resulted in all kinds of problems, including occasionally crashing the systems. Again, because cell phone users are stubbornly stupid, the cell phone companies just had to cope with the problem. They made the systems much more robust, and this sort of thing hasn’t been a problem now for a very long time. The FCC still doesn’t like airborne cell phones, simply because they tie up communication channels in multiple towers simultaneously, which wastes bandwidth. Basically, if your airborne phone is tying up resources on 5 different towers, that’s 5 ground-based users who potentially can’t get a channel to talk on. Most towers aren’t used to capacity, so it’s generally not a major problem.

7

Under the current rules, you can use phones and tablets in airplane mode thoroughout the flight, including takeoff and landing. More specifically, phones and tablets are required to be in airplane mode as directed by the crew, which in my experience is from the time the cabin door is shut prior to takeoff until the time the plane touches down on the runway.

You can hear the chimes of text messages being received as soon as the plane touches the runway upon landing, in my experience.

Laptops can also be used in airplane mode during the flight, but the crew will make you stow it for takeoff and landing.

Under the old rules, you had to actually shut off phones and tablets during takeoff and landing, but that is no longer the case.

8

When did they make that change?

I thought that rule was in place for two reasons. First, to prevent interference when the pilots most need their instruments to be working properly and need to be in contact with the tower, but second, so that people would be aware of their surroundings in case something went wrong and wouldn’t be focused on their phones or tablets while the crew is trying to give them instructions.

The first reason probably isn’t so much of an issue these days, but the second reason still seems very valid to me.

9

Thanks for this definitive answer, and I’m glad to hear that devices are still required to be turned completely off in certain situations.

10

The rule change was apparently announced on 10/31/2013.

11

On a tangent:
Get ready to get more nervous. The Infiniti Q50 is the first production “steer by wire” car, i.e. there is no mechanical link between the steering wheel and the front wheels. Like planes, there’s a high degree of redundancy in the sensors and actuators. Unlike planes, there is (for now) a mechanical backup, in that if the system senses a problem it engages a clutch to establish a mechanical connection (this also provides steering when the car is powered down, e.g. while coasting out of your garage to park it in the driveway). That clutch/ mechanical connection isn’t needed for normal driving though, and it wouldn’t surprise me to see it go away in the future.

12

In my last flight last December (ElAl Tel Aviv Vienna and back) we were told to put our devices in flight mode during take off/landing, the rest of the time we could connect via wifi to the entertainment / info /games system using a special app.

13

But, as noted in the OP, it’s close to certain that some devices in stowed carry-on bags and/or checked baggage were left on. And it’s highly doubtful that the autoland system can tell the difference between these and a device held in someone’s hand.

14

Obligatory SMBC.

15

I took an American Airlines flight in late December/early January; about a month ago today.

During takeoff and landing, some items (tablets and laptops) were asked to be turned off and stowed. Phones could be on, but in airplane mode.

Once you were at cruising altitude, you could have anything on all the way. Not only did items not have to be in airplane mode but they offered to sell you WiFi access through the plane.

16

Just to note that, AFAIK, WiFi isn’t the same as cellular signals. LSLGuy or someone else knowledgeable on such things might be able to comment on why (or even whether) WiFi doesn’t seem to be as problematic as cellular transmissions.

17

The communication was that your devices can now be taken out of airplane mode, so clearly the airline had no concern about cellular signals once cruising in the air.

I looked up the flight, it was an Airbus A319 if that’s relevant.

18

Excellent straight man there kenobi.

If you listen carefully to that they say, it’s that you can use WiFi, but the cellular phone feature must remain off.

So the right way to do that on most devices is to, before we leave the gate, turn *on *airplane mode which kills everything, then after takeoff separately turn *on *WiFi which overrides that one part of airplane mode while leaving Bluetooth, NFC, and cellular off. Then turn WiFi back off at the seatbacks, tray tables, carry-ons, etc., “prepare for landing” announcement. Then turn off airplane mode and begin shouting into your cellphone the instant we turn off the runway. And listen to the cacaphony as 150 phones receive a few texts and a thousand tweets & vital facebook updates apiece. :slight_smile:

Not that I or anyone else in the industry expects that everybody actually does that right.

The FCC also gets in the act. Using a cellular phone connection from an airplane is prohibited by them. FAA just passes that prohibition along to us, who pass it along to you. The FCC’s issue is the harm (described by others above) that airborne cellphones can do to the ground-based cellular network. Not what it might do to the airplane.

Ref Xema: You’re right we can’t get 100% compliance from every last forgotten device in the belly. But better to have 5 phones in the belly than 5 in the bellly and 205 in the cabin. It’s all about improving the odds.

Sorta paradoxically, the lowest tech radio nav system we use (wiki on ILS) dates from the 1940s. And, with only minor upgrades since, is the one we use for autoland guidance to the highest accuracy and precision when we can’t see to land. Being ancient and analog, it can have a problem with radio noise.

The early 1G analog and 2G digital cellphones really pumped out the noise at frequencies that were a problem. The later 3G & 4G models of cellphone / smartphone are less of an issue. Not zero, but less.

As well, the receivers in late model airliners (last 10-15 years) have mostly gone to software-defined radios (OK-ish wiki on SDR). Which can use modern high tech algorithms to suppress noise even though they’re receiving and understanding a low-tech 1940s-style analog signal.
Ref atamasama: Since you mentioned American I looked on their website to see their rules. The best info I could find was here: https://www.aa.com/i18n/travel-info/experience/entertainment/wi-fi-and-connectivity.jsp

If you got the idea from the announcement that you could make cellphone calls or enable the cellular radio, you misunderstood what they meant.
atasama’s confusion clearly demonstrates the semi-futility of trying to get the customers to parse these details correctly. But as long as it’s the law we’re stuck trying.

19

I’m not confused.

I’m a frequent flyer and I can say for sure for every airline that allows flight mode there are probably 6 or 7 that explicitly say phones must be switched off, period. If you’re seen using a phone, even while cruising, even in flight mode, you’ll be asked to turn it off.
Just this week I’ve flown Shanghai Air and China Eastern and it was definitely the case for these airlines. They said so in the safety video, and then during the flight nobody was using a phone (whereas, on a train in china, the majority of people will be using their phones to watch movies and play games)

However, one kind of flight I don’t take often is domnestic flights in the US. So perhaps this is why a number of dopers here are disagreeing with me?
I think it makes sense to allow phones in flight mode, just isn’t the way it is IME.

20

When I flew on United last October, the new thing was that the only way to watch movies was to download the United app and connect to the plane’s wifi. They wanted you to use phones, as the seat backs no longer had tv monitors. I have never been on a flight (domestic or international) that banned cell phone use outright even when in airplane mode.