Why Are We Still Powering Down All Electronic Devices on Airliners?

There’s no real reason for it.

A Twitter/Google+ friend of mine, Chris, linked to an article on the New York Times website today, “Fliers Still Must Turn Off Devices, but It’s Not Clear Why.” His comment on Google+ pretty much echoed my sentiments:

I do all my book reading on an iPad, and it’s annoying that I can’t read during the beginning and end of a flight, likely for no legitimate reason.

This blog post takes a logical look at the practice and the regulations behind it.

What the FAA Says

In most instances, when an airline flight crew tells you to turn off portable electronic devices — usually on takeoff and landing — they make a reference to FAA regulations. But exactly what are the regulations?

Fortunately, we can read them for ourselves. Indeed, the Times article links to the actual Federal Aviation Regulations (FAR) governing portable electronic devices on aircraft, 121.306. Here it is in its entirety:

121.306 Portable electronic devices.

(a) Except as provided in paragraph (b) of this section, no person may operate, nor may any operator or pilot in command of an aircraft allow the operation of, any portable electronic device on any U.S.-registered civil aircraft operating under this part.

(b) Paragraph (a) of this section does not apply to—

(1) Portable voice recorders;

(2) Hearing aids;

(3) Heart pacemakers;

(4) Electric shavers; or

(5) Any other portable electronic device that the part 119 certificate holder has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used.

(c) The determination required by paragraph (b)(5) of this section shall be made by that part 119 certificate holder operating the particular device to be used.

So what this is saying is that you can’t operate any portable electronic device that the aircraft operator — the airline, in this case — says you can’t. (Read carefully; a is the rule and b is the loophole.) You can, however, always operate portable voice recorders, hearing aids, heart pacemakers (good thing!), and electric shavers (?).

So is the FAA saying you can’t operate an iPad (or any other electronic device) on a flight? No. It’s the airline that says you can’t.

Interference with Navigation or Communication Systems

In reading this carefully, you might assume that the airline has determined that devices such as an iPad may cause interference with navigation or communication systems. After all, that’s the only reason the FAA offers them the authority to require these devices to be powered down.

But as the Times piece points out, a 2006 study by the Radio Technical Commission for Aeronautics found no evidence that these devices can or can’t interfere. Sounds to me like someone was avoiding responsibility for making a decision.

In the meantime, many portable electronic devices, including iPads, Kindles, and smart phones have “airplane mode” settings that prevent them from sending or receiving radio signals. If this is truly the case, it should be impossible for these devices to interfere with navigation or communication systems when in airplane mode. And if all you want to do with your device is read a downloaded book or play with an app that doesn’t require Internet access, there should be no reason why you couldn’t do so.

And can someone really make the argument that an electronic device in airplane mode emits more radio interference than a pacemaker or electric shaver?

And what about the airlines that now offer wi-fi connectivity during the flight? You can’t have your device in airplane mode to take advantage of that service. Surely that says something about the possibility of radio interference: there is none. Evidently, if you’re paying the airline to use their wi-fi, it’s okay.

What’s So Special about Takeoff and Landing?

Of course, since you are allowed to use these devices during the cruise portion of the flight, that begs the question: What’s so special about takeoff and landing?

As a pilot, I can assure you that the pilot’s workload is heavier during the takeoff and landing portions of the flight. There’s more precise flying involved as well as more communication with air traffic control (ATC) and a greater need to watch out for and avoid other aircraft.

But in an airliner, the pilots are locked in the cockpit up front, with very little possibility of distractions from the plane full of seat-belted passengers behind them — even if some of them are busy reading the latest suspense thriller or playing an intense game of Angry Birds.

Are the aircraft’s electronics working harder? I don’t think so.

Are they more susceptible to interference? I can’t see how they could be.

So unless I’m wrong on any of these points, I can’t see why the airlines claim that, for safety reasons, these devices need to be powered off during takeoff and landing.

It’s a Control Issue

I have my own theory on why airlines force you to power down your devices during takeoff and landing: They don’t want their flight attendants competing with electronic devices for your attention.

By telling you to stow all this stuff, there’s less of a chance of you missing an important announcement or instruction. Theoretically, if the aircraft encountered a problem and they needed to instruct passengers on what they should do, they might find it easier to get and keep your attention if you weren’t reading an ebook or listening to your iPod or playing Angry Birds. Theoretically. But there are two arguments against this, too:

  • You can get just as absorbed in a printed book (or maybe even that damn SkyMall catalog) as you could in an ebook.
  • If something were amiss, the actual flight/landing conditions and/or other screaming/praying/seatback-jumping passengers would likely get your attention.

But let’s face it: airlines want to boss you around. They want to make sure you follow their rules. So they play the “safety” card. They tell you their policies are for your safety. And they they throw around phrases like “FAA Regulations” to make it all seem like they’re just following someone else’s rules. But as we’ve seen, they have the authority to make the rule, so it all comes back to them.

And that’s the way they like it.

How Cell Phones Fit Into This Discussion

Cell phone use is a completely different issue. In the U.S., it isn’t the FAA that prohibits cell phone use on airborne aircraft — it’s the FCC. You can find the complete rule on that in FCC regulation 22.925, which states (in part):

22.925   Prohibition on airborne operation of cellular telephones.

Cellular telephones installed in or carried aboard airplanes, balloons or any other type of aircraft must not be operated while such aircraft are airborne (not touching the ground). When any aircraft leaves the ground, all cellular telephones on board that aircraft must be turned off.

There are reasons for this, but an analysis of whether or not they’re valid is beyond the scope of this discussion.

I just want to be able to read books on my iPad from the moment I settle into my airliner seat to the moment I leave it.

8 thoughts on “Why Are We Still Powering Down All Electronic Devices on Airliners?

  1. If my iPad could really be a danger to the airplane, why would they let me bring it on at all? They don’t trust with me water, but they trust me with something they say will cause interference with the airplane? Come on. This ridiculous rule must end!

    • Agreed! The problem is, the airlines say it’s an FAA rule and no one wants to make waves with the Federal government so no one fights back. The solution is to petition the airlines directly. They could actually use it as a marketing tool like Southwest’s free baggage check — allowing people to use portable electronic devices throughout the entire flight — as long as they don’t require tray table use (which blocks access to the aisle) during takeoff/landing.

  2. I’m working with the committee at my employer that’s exploring the use of iPads as electronic flight kits, replacing all of our paper manuals. There are two phases to the program, one in which we can use iPads during non-critical phases of flight (above 10,000 feet, or on the ground with the brakes set). FAA approval is pretty straightforward for this phase (in fact, I’m not sure that we actually need approval). The second phase would allow us to use it all the time and requires that we (among other things) demonstrate that it doesn’t cause any electromagnetic interference. I think they need to do the demonstration with the wifi/3G radio on and with it off, even though we’ll be restricted to having it turned off.

    While I think everyone realizes it’s extremely unlikely for there to be any interference with the wifi/3G turned off, I wouldn’t go so far as to say it’s impossible. Devices emit RF other than the RF they put out intentionally. But I’ve spent enough time in airline cockpits with all manner of electronic devices being used by jumpseaters in the cockpit and cell phones inadvertently left on to know on which side of the question I’d place my bets.

    Southwest tells you that you have to power down your devices completely, not just put them in airplane mode. I’d venture to say that half the people with iPhones and iPads don’t even know that it’s possible to turn them off completely, much less how to do it.

    • Thanks for this. It’s good to have input from someone more experienced with airliner systems than I am.

      An article about cell phones on airliners on Wikipedia suggested that the reason we don’t know for sure whether there’s interference is because no one wants to foot the bill for the extensive testing that would be required to know for sure. I’ll take that a step further and suggest that whatever testing is done, additional testing would need to be done every few years to account for advances in technology.

      As for airplane mode; that’s the only thing I do. Given that a number of people on every flight actually forget to turn their cell phones/devices off when asked to, I don’t think airplane mode would ever cause a problem.

  3. I actually once asked the stewardess this, and what she said goes along with your theory: it’s not interference, it was that they wanted our full attention during take-off and landing because that’s when things were mostly likely to go wrong. She also mentioned that they are required to make sure that all passengers see the safety video, and people are more likely to do so without their headphones in. (I have no idea if this is all true, but I wanted to listen to my iPod, so I asked…)

    As far as cell phones go, I hope they stay off. I’ve no desire to listen to the person next to me have a three-hour phone call.

    • While I can understand them thinking they’ll have more of our attention, there are plenty of other non-electronic devices to distract us.

      If they really want us to watch the safety briefing, they should make it more entertaining. I was on a SW Airlines flight one Christmas season when they sang the safety briefing to the tune of Jingle Bells. Now THAT was worth watching.

      I’m definitely with you on the cell phone policy. It would be a nightmare to have to listen to telephone conversations the entire flight — especially with people shouting into the phone to be heard above the other noise. Fortunately, there is a real law preventing this and neither the FAA nor the airlines can overrule it.

  4. Hello!

    Found your blog reading on the 135 stuff. Living in Europe and considering getting an AOC, reading about the 54 pages for the 135 seems like Christmas come early! :)

    As a Pilot and radio amateur (with a professional background in Electronics Engineering) I think turning all that consumer quality electronic gear off is a very sensible idea indeed!

    Consider this – You are in solid IFR and flying a GPS approach. The GPS signals are transmitted at a power equivalent to a 50 watt domestic light bulb. Those signal have to pass through space and our atmosphere before reaching your satnav after a journey of 11,500 miles. Compare that with a TV signal, transmitted from a large tower 10 – 20 miles away at most, at a power level of 5-10,000 watts.

    The typical received signal power from a GPS satellite is −127.5 dBm = 0.178 fW. The f is for “femto watt”. 1 FW is a quadrillionth of a Watt or 1,0 × 10-15.

    (The above value is from Wikipedia)

    So that is not a lot of power. For me at least it’s real easy to see how a consumer product gone bad (and in much closer proximity to the receiver than the transmitter) could overpower that signal. Maybe not from the factory, but after it has been dropped a few times anything can happen.The GPS L1 frequency is 1.5754 GHz but there is something called harmonics. Something could be build for 787 MHz (close to cell frequencies) or something else and if it malfunctions and luck is bad it could hit the “right” frequency to kill the GPS signal at double that frequency.

    And it would be impossible and unreasonable for a flight attendant to check if all devices are FCC approved and working as they should. It would require that they sweep the airplane with a spectrum analyzer. And not all devices are FCC compliant, perhaps someone has a device made in China that has harmonics everywhere?

    A friend of mine found he couldn’t use his ham gear from one day to the next. Why? The neighbor had bought a new TV. He offered to help quiet it down from the RF perspective and he opened it up for a look. The places where the RF filters where supposed to be where unpopulated on the circuit board and replaced with two wires! So you just can’t trust random consumer products. And a jet has maybe 200 seats, so think of the amount of potential devices that are “up in the air” each year.

    The ILS is 108 MHz and up, the Glide Slope. Frequency range, 329.15 – 335 MHz. Marker 75 MHz, etc. so if you consider all the many frequencies in use, and all the possible devices, past, current and future, the many possible failure modes of electronics, and add Murphys law you just can’t be sure that nothing will go wrong even though it seems “fine” using electronics most of the time!

    Just my cents!


    • Great and thorough comment. I’m a pilot, radio amateur, and radio engineer myself and the dangers of RF interference from commercial devices cannot be understated. Radio interference is a very complex subject.

      The power levels from a GPS or even ground-based nav signal are mind-bogglingly low (often at the very limit of detectability due to the constraints of the laws of physics), and so the power from a local interference source can be several orders of magnitude higher given that it didn’t travel as far since power drops as the square of the distance!

      The probability is clearly very low, as common sense would tell you, but the bottom line is that avionics are not generally designed to operate with interference present, and commercial electronics (as noted) are not designed to very high standards. They leak RF all over the spectrum at varying degrees, with big variations between devices even off the same assembly line.

      Modern systems like GPS are probably just going to say “signal unavailable” if there’s interference, but anything like a localizer, glideslope, or VOR receiver may start reporting erroneous data, possibly taking the plane off course a little or a lot. Not a happy situation on approach to minimums in IMC.

      There are reported and documented incidents of portable electronic devices causing an airplane’s autopilot to act wonky, probably due to affecting the nav receivers, so it does happen. It’s just very unlikely.

      Until avionics systems are carefully studied and designed with exceptional shielding, at a great cost, then the use of electronic devices during takeoff and landing (the most critical phases of flight) is a bad idea to be on the safe side.

      I hope that’s informative. It is indeed a confusing subject.

What do you think?