While this is valuable information, it is all anecdotal: you're assuming that the incidents you experienced were due to electronic devices, but the FAA has never tested this, so it's a single datapoint where we don't even know how many (if any) passengers had active devices.

If the FAA were serious about flight safety, surely they would be testing this to a scientifically acceptable standard. Then, once we have the data, and assuming that there is a problem, phone makers could introduce some kind of "do-not-send" code that planes can broadcast so that phones stay quiet during flight.

The FAA has announced plans for an industry working group: http://www.faa.gov/news/press_releases/news_story.cfm?newsId...

The difficulty lies in testing the airplanes in such a way that you cover _all_ potential devices, past present or future, with or without manufacturing defects. This is not an easy task.

You're approaching the question from the viewpoint of a passenger that _wants_ to use your device. So naturally you pull out the anecdote card and say that since you can't _prove_ it's caused by cell phones, then cell phones should be allowed.

Unfortunately, that's not how the FAA, airlines and pilots think. What they think is that if there is a _minute_ chance that turning off cell phones in flight critical phases can give even a _marginal_ improvement in instrument reliability, then it's worth it for them. (And if you don't like that, you can always get yourself your own plane, a PPL and do whatever you like.)

Likewise, if you're a doctor and some medical equipment (say a heart monitor) at the hospotal is technically capable of running Quake since it's using Linux, you still don't want to install Quake on it if there is just the slightest chance that doing so could cause the heart monitor to hiccup. If something fails, it's your job on the line.

So to put this in perspective, a bad person could crank up their phone and prevent all sorts of safety and assistance systems on a plane from working?

Then why ban a bottle of water?

So how come in a meeting room at a conference, with maybe 200 people actively using multiple wireless devices plus WiFi access points broadcasting, nobody's computers are affected? Are avionics really that sensitive to environmental RF interference?

Those devices are all transmitting at low power, usually to a WiFi / cell base station nearby. The issue here is when several devices are transmitting on high power at the same time. Also, a computer is a single shielded device with most data running on a single motherboard and a few cables. Avionics are well shielded, but the cables and antennas run the length of the airplane and there's a _lot_ of devices in a typical setup (ADF, VHF NAV/COM, GPS, TCAS/ADS-B to mention some, all of it duplicated for redundancy), so the chances of one of them being affected is a bit higher.

Thanks for taking the time to comment here. I'm curious of this is such a widespread problem, presumably organizations like the FAA and researchers would have survey data from pilots that demonstrate how widespread the problem is (I would think pilots unions in particular would advocate for such information). Are you aware of any systematic survey of pilots to assess how frequently this happens?

There are actually some studies conducted. Note that these are _suspected_ interference from personal electronic devices and also incidents with passengers unwilling to turn them off: http://asrs.arc.nasa.gov/docs/rpsts/ped.pdf

Of course, all of this is anecdotal so it won't fly here on HN. :)

The real difficulty is that when an instrument malfunctions, that can be for any number of reasons. It's not unusual for malfunctions to occur, which is why airplanes have redundant avionics. However, there seems to be a few instances where the interference stopped after a passenger turned off their devices.

Well in my experience, small incidents are quite common, maybe a pilot can experience 4 to 6 a month. The hard ones are quite rare (thankfully) something like 1 every 2 or 3 years, maybe less(for a pilot flying 900 hours/year). But this is far from hard data, more like pilot and engineering informal chat. There is maybe more than the cell phone factor here, other problems involved that are hard to detect like a sensor with a corrupted signal, a bad cable (some miles of them at a plane), a software bug. I don´t think there is an easy solution. Thankfully it is very rare that this happens in a delicate situation (like a cat III landing with 0 visibility), and even then you can go around and call the passengers to disconnect their cellphones. It is not like a terrorist can come with a super evil cell phone and kill everyone that easily. But is a safety concern none the less. I wouldn´t recommend that politicians legislate about this randomly.

First of all, how do you know phones are the cause of this?

And secondly, if this is true, then how come people are even allowed to board flights without their persons and bags being searched for electronics that are turned on? I've flown cross country while forgetting to turn off the phone in my pocket. If it's that dangerous, why am I allowed to do that?

Well as far as I know you are not allowed. But thankfully it is not enforced, if your phone is not visible nobody is not going to tell you anything. That doesn´t meen that somebody at the cockpit keeps trying to reset a computer with no results. We don´t know phones are the cause, there is no way to know that unless you analyze all the signals of all the data busses and check what is going on. Of course not all the malfunctions are due to the phones, but we have enough of them to tell you that phones have something to do with some specific failures we experience. How much? nobody knows.

If this is true (and I don't really believe it) then all electronic devices should be banned from the cabin and carried in the checked luggage AND flight critical systems should be designed to be robust against such interference in case there is a terrorist attack using a hidden electronic device designed to operate at many times the power.

You didn´t really read the post do you?

I did, if you really think 3G phones en-masse trying to connect at maximum towers is the cause of computer crashes that you as a pilot describe as scary then someone setting out to do harm could design a unit that is easily hidden and for a short time could produce a much greater interfering signal.

There are two real possibilities:

1) Interference is not a real danger and not the cause of the issues you have on occasions experienced.

2) Interference from mobile phones is a genuine danger to aircraft systems.

If (1) is true interference is not a valid reason to ban electronic devices.

If (2) is true the current safeguards aren't high enough and the protection should be greater. If passenger jets are vulnerable to interference from normal 3G phones then it is a potential form of terrorist attack to create massive amounts of interference at a critical point in the flight deliberately. Probably much easier than messing about with binary liquid bombs.

Edit: Note that I believe that case (1) is by far the most likely and that I think that 10-100 times normal power device would probably be feasible if you didn't care about battery life although it might make sense to hide it in a laptop and use a bigger antenna than keep it in a phone package.

Well I can not surely say what causes each failure (not even the manufacturers know for sure, that is why they make tests continuosly), of course not all the failures are due to phones. But saying that phone interference is not a possible danger to the integrity of the flight is quite bold, as I doubt that you have experienced a failure of that kind as a pilot or as a flight engineer. I also doubt that you know what can be the outcomes of a misguiding indication or or complete fail of a system. You are surely oversimplifying the matter. Planes are not data centers, they experience a great deal of vibrations, temperature changes, extreme humidity changes (from very dry to lots of condensation). All the circuits, cables, sensors computers, pipes, pumps, metal sheet, everything inside a plane will behave over time in strange ways that are not fully understood even today. A weakened electronic sys(with already corrupted signals) may not support the kind of troubles that a nominal one could do with ease.

The problem with your claim is that it doesn't pass even basic rational examination of the known physics involved. Radio waves from cell phones are only one source. The transmitter in most cell phones is around 0.3 watts. Loosely speaking, a cell tower transmits at around 10 watts per antenna. Radio stations transmit at wattages measured in the kilowatt range. HAM radio operators can transmit at 100 watts.

All of these signals are flying around the atmosphere all the time. Distance certainly plays a role in effective power at the point of reception, but a tiny 0.3 watt cell phone transmitter isn't bombarding the aircraft with any more RF than an FM transmitter that is miles away from the airport.

The reasoning just doesn't stand up.

The third option is: Cell phones can in remote circumstances cause interference, but seldom enough to warrant banning all electronic devices with the massive revenue loss that would ensue. Likewise people are still allowed to bring lithium batteries even if they pose a fire hazard with several documented in flight incidents.

In the real world, regulations are the result of trade-offs and not absolutes. It's just that the current trade-offs seem to err on the side of safety.