Phone usage during flight
 

Last November I was on AS459 seated in 2A. We had just passed 10,000ft. Captain turned off the seatbelt sign, told we can use electronic devices, the usual. Seated in 1D was a lady. After we where told we could use electronic devices she whipped out her little Verizon flip phone and started making a call! "hello?, can you hear me?!, No i'm on the plane". The FA was talking to a passenger in economy but when she saw what was happening she sprinted up to her, and told her to put it away. The lady insisted she didn't do anything wrong but anyone who paid any attention to the safety announcements knew she was wrong. I'm surprised she could even get signal up there. I wonder how many people have tried to call someone in flight?

Your cell phone selects the strongest signal from the towers that are in your area. Normally it would be the nearest one. As you move, it may select a new tower as the signal strength changes.

In a plane, the system gets confused because you are at a higher altitude and there are many more towers in range. Planes also move faster than cars on the ground. Basically, the system isn't designed for that sort of use. If you get service at all, it will be more erratic.

It's more of a service quality issue that it is safety.

There's two parts to it. First, it can really cause problems with the cell system, for the reasons already posted. Second, the FAA really doesn't like anyone using any kind of device that transmits energy (RF, etc) on an aircraft. All the systems installed on the plane are tested to make sure they don't interfere with other systems. A normally working phone might not bother anything, but a broken (or deliberately modified) one certainly could.

joe

Affecting ground communications is a concern. Affecting avionics is not. It's never been proven that cellphones interfere with avionics.

Hasn't it???

I fly light aircraft. I have, on one or two occasions, taken off with my cellphone still switched on in my pocket. The reason I noticed it was on was the fact that it interfered with the aircraft radio.

OK, I appreciate that the telephone of a passenger in seat 35A (or even 2A) is going to be a lot further away from any avionics than a telephone in the pilot's pocket.... but to claim that there is no proof that cellphones interfere with avionics is not correct. I get that proof every time I fly a light aircraft with my cellphone accidentally left on.

Depends on the definition of proven. IEEE (Institute of Electrical and Electronic Engineers) one of the authorities on electronic interference have extensive published peer reviewed research in this area. Here are a few articles. You can find more by doing a simple literature search.

Phoning and flying
Cell Phones Use in Aircraft - A Short-Term Reality?
PED Interference Reporting System in Japan
A description of the software element of the NASA portable electronic device radiated emissions investigation
Cell phone/w-lan emissions interference with narrow body aircraft communication and navigation systems

Showing that something is technically possible is not the same as showing that something is an actual risk in the real world.



However, real world experiences do have a real correlation to real world risk.

There have literally been hundreds of millions of commercial flights with billions of radiating devices (cell, bluetooth, wifi, etc...) with zero accidents attributed to them. This makes the real world risk a total of 0.0000000000%

One time my phone "turned itself" on somehow in my hand luggage and upon landing I had loads of SMS messages welcoming me to countries like Afghanistan and Iran. :)

There is a difference between a cell phone being turned on and a cell phone in active use. Use of cell phones create a significant risk of problems on board a commercial aircraft. If you really want to see air rage, permit the use of cell phones in a crowded US-domestic airliner. Everyone will be shouting over their neighbor because their conversation is so important.

^ Remember that airlines have blocked VOIP calls onboard as well.

On Sept 11, 2001, many people in the doomed airplanes pulled out their cell phones to call loved ones and say goodbye. A lot is known about what actually happened during the hijackings from cell phone communication during the events.

Begging the question: Why would Boeing, Airbus, Embraer, Fokker, etc, make multi-million dollar aircraft, only for them to be significantly impacted by a $50-$100+ device like a cell phone? [err, better phrased, why wouldn't they plan for such possibilities?]

Exactly. The prohibition on cell phone use may well be the last vestige of civility on US domestic flights. Take that away, and every excruciating cell phone conversation you've overheard on the street gets moved one foot away from your ear.

Though maybe it wouldn't be so bad if they installed signal relays onboard and charged for cell phone use, something like $5/minute (comparable to Airfone rates). At least it'd keep calls relatively rare, and bring in another revenue stream.

bolding mine: I think it has to do with altitude as I wanted to use my cell to snap a picture of a bunch of F/t'ers all on the same flight but I had to turn my phone on and then flip it into airplane mode and when i turned it on, no signal at 28,000 feet but one another flight, i was in 3c (last row of f/c) with jackets hanging behind us and no sooner did we clear 12,000 feet (listening on Ch9), a cell phone in the pocket of the jacket hanging up behind me rang with an incoming call :eek:

I dread the day, I really do, when (or if) mobile/cell phones are allowed to be used on planes. Gaudy ring tones going off all the time, inane conversations in every second seat ("No, I'm on the plane..."): I can just as well imagine it. :rolleyes:

I doubt that one cell phone would interfere with avionics. But a likely scenario is 300 pax fire up their mobiles as the plane is on final approach to say, "I'm landing." Perhaps that'd send enough watts to turn the altimiter off by 6 feet?

Think of the roadside signs, "No 2-way radio broadcasting - blasting area." The 2 little wire leads on a blasting cap act as antennas. Yes, you might get through to the avionics.

On the other side, planes get hit by lightning all the time and just keep on chugging. Is there an EE on Flyertalk to 'splain what a cell phone can do that lightning can't?

So why do they allow everyone on the plane to use wifi on their laptop?

Six feet can be the difference between landing softly and ramming the plane into the ground, thus damaging a multi-million dollar piece of equipment.

Just saying.

Interesting thread. Just curious as to why you waited a year to post it?

My guess is lightning is broadband interference (i.e. its energy is distributed over the full frequency spectrum), but only for a brief instant. Cell phones emit in extremely narrow frequency bands and broadcast continuously. If this frequency band happens to be at a frequency that the avionics use, it therefore has more potential to cause sustained errors (i.e. the proverbial "altitude needle" is off by a certain amount for a long time, instead of just twitching when a lightning strike happens).

Also, it's easier to design electronics to ignore broadband interference (can detect simultaneous signal at other frequencies) than narrowband (looks just like the signal you're interested in).

I was waiting for someone to ask that;). New member of FT.

Welcome. :). It is an interesting thread. And good location.

Just as the DL gate agent in ASE said "I've never seen someone from EAT before"

"My colonoscopy last week indicated a polyp..."
"Can I get a refill for my Viagra? I'm out of town and..."
"No, you need to put Huggies on her at night. The daytime diapers leak..."
"I've looked at the numbers, and it looks like we will have to lay off Fred..."
"And how did his wife find out..."
"You've never had a root canal job? I have, and it goes something like this..."

The possibilities are ever so endless it makes my head hurts.

I did get a laugh or two out of your examples though^

Some of those sound moderately entertaining. All I ever get are interminable, boring business conversations like "So we need to re-run the numbers on the Anderson account, vis a vis the updated tax treaty ....", spoken in a loud, sloooow monotone :P

I see what your getting at, but that would be interesting for maybe twenty minutes max. A transcon flight with someone talking about how they spent there weekend would be annoying. Look up Alaska Airlines | "Chatter" on YouTube for a really good example.

what sort of pilot are you ? " everytime I fly with my cell phone switched on " what else do you accidentally forget to do ? :td:

Um, same sort as a driver who accidentally leaves his blinker on once in a while after a lane change. Cripes, no need to be nasty, everyone makes far worse mistakes. Are cell phones even prohibited aboard private aircraft flying VFR?

What a load of hysterical hyperbole. [just sayin' ;)]

Lightening can, and does, cause damage, interference, and system failures.

They tried banning in-flight lightening strikes but the thunderstorms pay even less attention to the rules than do frequent fliers.

You mean they try to block VoIP calls. Anyone with IP experience can get around that block thankfully.

And as for the issue of causing problems with the cellular network, that was an ancient problem solved long ago. As noted there are thousands of cell phones left on during flights every single day. The cellular system had to overcome this issue many years ago.

Mythbusters had an episode a while back where they explored cell phone interference on avionics. They had an airplane cockpit and a radio that simulated cell phone frequencies but with adjustable power levels. IIRC there was no effect on the avionics when it was at the power level of 1 or 2 phones but when they dialed it up to higher levels to simulate many phones in use it had a noticeable effect on distorting some of the instruments.

The same reason several airlines permit in-flight GSM/GPRS usage: it has been tested and certified by the appropriate agencies. Among other things, having a small cell/transponder in the aircraft means that the individual devices can operate at much lower transmit powers. This reduces the potential for impact on the avionics. It also makes the communication much more reliable for the customer and easier to manage for the provider.

To me the ultimate argument against cell phone causing interference is that if it were true, we would not be allowed to bring phones onboard. They would be confiscated at the security checkpoints. If cell phones are dangerous, how dangerous does that make 5 ounces of water or toothpaste? Or a jelly doughnut?

My son was flying to EWR last Christmas and it was the beginning of that massive snowstorm. I knew he was in-flight but called his cell phone figuring I'd leave a message suggesting that he take the train into NYC, where he was visiting family, rather than risk getting stuck in a taxi for hours in a snowstorm. (He's 25 but hey, I'm his mother and I tend to micro-manage my own travel, too.) He answered the phone. Yes, they were in the air. I freaked out, gave him the message and rushed off the call before someone caught him and put him in plastic handcuffs. I think it was MDW and he seemed to think using the phone was permitted. Happily, the snowstorm hadn't started when he landed and he got a taxi with no problems.

I agree that I don't want a cabin full of people chattering on their cell phones- I've run into that in trains and it can be obnoxious. I remember to turn mine off 99% of the time and also disable the Wireless feature on my laptop and iPod Touch.

There is no regulation which prohibits the carrying of devices which can cause interference--The regulation only prohibits their use.

Right, but I believe stimpy's point is that if cell phones posed a legitimate danger of bringing down an aircraft, there would be regulations prohibiting them onboard altogether.

Like guns and other weapons.

It doesn't matter what any of us think is actually dangerous or not. The FAA regs prohibit the use of any transmitting device onboard the aircraft in flight. It's much easier for them to write the reg that way than to codify all the good devices vs bad devices. And there are definitely some bad ones out there that fall under that regulation. I don't remember where I saw it, but I do recall a test of some common household RF devices. RF operated toys (cars, trucks, etc) were really bad, causing all sorts of interference with nav equipment.

joe