The Real Reasons Phones Are Kept Off Planes

jcatcw writes "Mike Elgan argues that the the real reason that cell phones calls are not allowed is fear of crowd control problems if calls are allowed during flight. Also, the airlines like keeping passengers ignorant about ground conditions. The two public reasons, interference with other systems, could easily be tested, but neither the FAA nor the FCC manage to do such testing."

Comments

Re:funny

[Quasar1999]

Actually, ask anyone that knows how cell towers work, and your real explanation would become evident. Cell phones try to communicate with as many towers at once as possible, this is required so that you can walk from one cell's coverage to another's without dropping your call... a typical phone sees anywhere from 3 to 6 towers at once depending on geography and density of cell towers. Throw that phone up a few thousand feet, and I've personally seen my blackberry connect to 40+ towers at once. This eats up valuable bandwidth at each cell tower, not to mention the fact that you come in and out of a cell's coverage area so fast that it's impossible for your calls to be handed off properly between the cells.

Oh, and good luck with the E911 crap... In the course of a minute, you've gone from the east end of a major city to the west end according to the cells.

Author is an idiot; the carrier reason is valid

[ChaosDiscord]

Mike Elgan, the article's author brushes off the problem of an airborne cell phone seeing a large number of cell towers at once. He claims it could be easy to fix with a software upgrade to the towers. Nonsense. The fundamental problem is that there is only a finite range of frequencies for cell phone calls. The more towers a given phone's signal is visible to, the more towers whose frequencies you're chewing up. Redesigning the system to support cell calls would be massively expensive. Is the value of being able to make cell calls from a plane really that valuable? Who is going to pay for the overhaul? Elgan is just whining.

Elgan points out that Europe is working on making this work. Tellingly, they're not just letting the phones connect to towers normally; they're shielding the cabin and routing connections through dedicated on-plane hardware. This is reasonable as it means you have a single source (the plane's hardware) that can far more efficiently utilize tower frequency space. Furthermore, the cost of making the changes falls on the airlines, who will pass it on to the logical people: the fliers who want to use this service.

Re:I don't buy the crowd control thing

[div_2n]

People tend to talk louder on cell phones than regular phones. There is no feedback of their own voice.

For an article with *real* research done...

[Himuanam]

From the IEEE's Spectrum magazine last year, they actually measured RF signals on flights and reported on the results. No smoking gun where an accident was caused by a cell phone, but still interesting nonetheless (and no ads!). http://www.spectrum.ieee.org/mar06/3069

Re:I don't buy the crowd control thing

[ffejie]

You are indeed correct. JetBlue landing gear mishap.

Has been tested

[DaveAtFraud]

The effect has been idependently tested and confirmed:

http://www.post-gazette.com/pg/06060/662669.stm

I think I'll trust real research from CMU over a vapid so-called journalist who probably just can't stand not yapping on his cell-phone.

BTW, it doesn't matter if some or even nearly all cell phones don't cause interference with flight controls. All it takes is one person using one that does and things get ugly. Likewise, most airplanes have a mix of avionic equipment. Some of it is new where the cost/benefit makes it worth it for the airline to upgrade and some of it is old. Rather than test each airplane independently, it makes more sense to just say "no" until someone comes up with a way that is known to be absolutely safe regardless of the equipment on the airplane.

Cheers,
Dave

Re:funny

[LordEd]

I would rather insert actual satellite phone rates. Iridium is a satellite network provider. Their phone airtime rates can be found here

Looks like the cost is about $1.29 / minute. I don't know what kind of phones they might use, but a basic phone costs about $1500 according to here

Testing Isn't Easy

[Helmholtz Coil]

Speaking as someone who's tried to get gear flight certified, I can tell you that testing is never easy. Granted, it's definitely easier to get something approved that isn't going to be part of the plane but rather just another carry-on, but there's still a lot of work involved.

I think it probably boils down to cost and caution. The testing is expensive, and nobody wants to be the one that approved cell phones if they end up causing a plane crash.

Re:9-11?

[hedwards]

I don't think so. My recollection was that some of the people aboard the flight which crashed in PA called loved ones. And had awareness from those phone calls of what was going to happen. I am pretty sure though that calling 9-11 wouldn't have worked as it is the number in a huge number of places. If the call got to two different towers straddling areas codes, it would probably have not gone through.

Re:funny

[SerpentMage]

If a Russian plane flies into the US it has to be certified by the US. That usually means either Airbus, or Boeing or some other smaller plane manufacturer that has already been certified. If you want an interesting flight (my brother tells me this) fly in Russia using a domestic airline.

Cell phones are already tested for interference because otherwise they would interfere with other devices. Cell phones are certified to use regulated bandwidths. It's walkie-talkies and cordless phones that you need to be worried about since they use uncertified spectrum's.

The reality is that most of these things have already been verified as that is why you have little stickers on the back of the device indicating that they have been certified. And interestingly enough most countries have similar certifications because otherwise they would have wireless nightmares.

re; Are you *sure* this is still an issue?

[King_TJ]

I've seen that same explanation stated several times before when this discussion came up. But the last time I read about it, I believe it was a message thread on HowardForums.com - a site specifically made to discuss cellphone technology. Many users there work in the industry in one capacity or another. One of the guys who claimed he worked on engineering the cell tower infrastructure said that this is really not a true statement. Yes, the phones are designed to communicate with any towers within range. BUT - the cell towers have the ability to handle situations such as a phone suddenly "appearing" on 40 towers at the same time. They have software that knows such things aren't possible in normal cellphone operation at ground level - so it ignores the signals on all but a few towers at a time.

He claimed that in reality, this process doesn't "tax" the towers inordinately at all. The "bandwidth" tied up is no more than a regular call would tie up, since the towers are rejecting the extra instances of the connection to the phone. There's simply a small amount of overhead involved in the towers passing along the information to each other about the status of your connection.

(I believe this type of software also comes into play for handling problems of "cloned" cellphones. If a connection shows up simultaneously on towers that are spread far apart, they know they're dealing with not just 1 legitimate phone, but also a duplicate in service elsewhere.)

Re:re; Are you *sure* this is still an issue?

[w9wi]

On any kind of cell phone, you're only connected to one cell at a time.

Let's say your phone is connected to Cell A and is talking on channel 375. You aren't using Cell B. But you are using channel 375. If Cell B tries to assign channel 375 for someone else's call, your phone is going to interfere with theirs. If you're flying at 15,000 feet, you're only going to tie up one cell at a time -- but you're going to tie up channel 375 for as far as 100km or more.

Re:funny

[rv8]

The problem is much more difficult than simply certifying every cell phone design as safe. The problem is that a small number of cell phones might have shielding that becomes ineffective, either through a problem during manufacturing, or something that happens in service (dropped cell phone, cell phone disassembled and reassembled by curious geek, etc).

And, it is possible that the avionics or coax cabling in some aircraft might be not quite up to snuff. So, most aircraft of a given design are OK, when coupled with most cell phones. But put a defective cell phone in the right place in the right aircraft, and you could have a problem.

Several years ago I spoke with the captain of a Challenger business jet who told me an interesting story. They were in cruise, when suddenly the VOR indications in the cockpit started doing very strange things. He sent the copilot back in the cabin to see if anyone was using an electronic device. He found that the CEO's son was playing with a Game Boy. The Game Boy was turned OFF, and the VOR indications returned to normal. The Game Boy was turned back ON, and the VOR problems returned. Game Boy OFF for the rest of the flight.

Also see another report of problem caused by Game Boy.

Mythbusters already did it.

[nbritton]

Back in season 3:

"It was found that cell phone signals, specifically those in the 800-900 MHz range, did interfere with unshielded cockpit instrumentation. Because older aircraft with unshielded wiring can be affected, and because of the possible problems that may arise by having many airborne cell phones "seeing" multiple cell phone towers, the FCC (via enforcement through the FAA) still deems it best to stay on the safe side and prohibit the use of cell phones while airborne." -Wikipedia

You can read more about it here: http://kwc.org/mythbusters/2006/04/episode_49_cell phones_on_plane.html