NY Times tech blogger Nick Bilton has a thorn up his ass about the FAA prohibitions on electronic devices during take-off and landing. Bilton just cannot understand why some pilots are now being allowed to use iPads in the cockpit for paper flight manuals but he cannot use his Kindle for the take-off and landing parts of the flight.
As it happens, this is one of Goldy’s pet peeves as well. Neither person seems to believe that electronic devices can affect flight safety during critical (take-off and landing) phases of flights. At least Goldy leaves it at complaining and denial. But not Nick Bilton.
Bilton decided to do something about it. You know, use science and technology to “prove” that electronic devices are safe.
What he did, however, amounts to horse shit. As I show below, Bilton, sets-up and then destroys a straw-man argument.
I don’t know much about Bilton, but from reading a few of his columns on this topic, I must conclude one of two things: (1) He is going out of his way to be deceptive, or (2) for a tech writer, he is pitifully ignorant about radio and aviation. I know a bit about each, so let analyze:
Bilton asks the F.A.A., American Airlines, and Boeing about the problem with electronic devices. And though “each [gave] a radically different rationale that contradicts the others”, he still correctly concludes that the problem comes from “electrical emissions.”
For answers, I headed down to EMT Labs, an independent testing facility in Mountain View, Calif., that screens electrical emissions of gadgets that need to pass health, safety and interference standards.
So far so good. But here is where things go astray.
Gadgets are tested by monitoring the number of volts per meter coming off a device. The F.A.A. requires that before a plane can be approved as safe, it must be able to withstand up to 100 volts per meter of electrical interference.
When EMT Labs put an Amazon Kindle through a number of tests, the company consistently found that this e-reader emitted less than 30 microvolts per meter when in use. That’s only 0.00003 of a volt.
So…what we have learned is that the RF emitted from an Amazon Kindle (clearly with the Wifi turned off), isn’t going to overload the plane’s electronics. This is a trivial finding. I’ve not found any credible source claiming small consumer electronics would cause brute-force RF overloading of the plane’s onboard electronics. (Some automobile computers will overload in the presence of strong RF fields…not from a mere Kindles, though).
“The power coming off a Kindle is completely minuscule and can’t do anything to interfere with a plane,” said Jay Gandhi, chief executive of EMT Labs, after going over the results of the test. “It’s so low that it just isn’t sending out any real interference.”
The problem isn’t with interfering with electronics, in general. The problem is interfering with radio receivers, that are designed to receive very low voltage signals and do things with them. A high quality VHF receiver has sensitivity to signals of around one microvolt. So an electronic device putting out a 30 microvolt signal in proximity of the VHF radio’s antenna can potentially cause great interference.
A proper test for interference potential involves not just measuring total RF field strength, but also looking at the specific frequencies being emitted, and evaluating the potential to interfere with the aircraft’s numerous radio receivers.
But surely a plane’s cabin with dozens or even hundreds will? That’s what both the F.A.A. and American Airlines asserted when I asked why pilots in the cockpit could use iPads, but the people back in coach could not. Yet that’s not right either.
“Electromagnetic energy doesn’t add up like that. Five Kindles will not put off five times the energy that one Kindle would,” explained Kevin Bothmann, EMT Labs testing manager. “If it added up like that, people wouldn’t be able to go into offices, where there are dozens of computers, without wearing protective gear.”
Bilton reaches for the idiotic!
The problem with a planeload of electronic devices is that they each put out relatively weak signals—usually on different frequencies. Computers have built-in oscillators, radio receivers have at least one oscillator. With two hundred devices of all types—portable games, laptops, e-readers, cell phones, AM radios, FM radios, GPS receivers, TV receivers, satellite radios, scanners—putting out these weak signals on five or ten frequencies each, the possibility of interfering with the aircraft communications system is greatly increased.
To make matters much, much worse, numerous electronic devices are transmitters, sending out much stronger signals than the spurious emissions measured from the Kindle.
For example, if you have a smart phone, it transmits on two or more different cell phone bands. It also his a Wifi transmitter. And it has a blue tooth transmitter (in addition to receivers for all of these and GPS). Each transmitter puts out relatively strong signals on the design frequency. But they also put out weak spurious signals—harmonics, and signals generated by internal oscillators or produced from mixing different frequencies together. These spurious signals my be several orders of magnitude stronger than the Kindle (without Wifi) emissions.
Now we have 200 electronic devices putting out thousands of passive emissions (from computer and receiver oscillators), and a subset of these devices are transmitting on Wifi, bluetooth, and pinging for cell phone service. The potential for interference has become non-ignorable.
Here’s a true story of interference and flying. Three summers ago, I was flying my small plane from Seattle to Madison, WI. At the end of a long day, I was flying the last leg across Montana—over an area with very few airports. It was getting dark, I was unfamiliar with the area, and the destination airport, and the distance between airports meant I had less fuel reserve than I would have liked.
To add to my concerns, the communication radio started receiving an annoying series of sharp pulses that would come an go. I couldn’t get rid of it by changing the radio frequency, the pulses were still there. It spooked me a bit. But after a couple of moments, I deduced that it was my cell phone “roaming”. I had forgotten to turn it off at my previous fuel stop.
The interference turned out to be a minor nuisance during a non-critical phase of a stressful flight, and I was able to diagnose and correct the problem. But it distracted the hell out of me for a few minutes while figuring out what was going on.
The last thing you want during a critical phase of flight—say, during a take-off or landing—is a pilot being distracted with, “what the fuck is going on with the radio?!?” Chances are very good the flight will be unaffected. But with tens of millions of commercial flights in a year, the “small chance” of a problem building out of a distraction turns into an occasional “incident.”
And it isn’t just communications radios that are susceptible to interference. Modern flying, particularly during the landing phase, involves numerous navigational, collision avoidance, and instrument landing services that make copious use of radio receivers all over the RF spectrum. GPS is a fantastic navigational tool, but it has planned and unplanned outages and can be shut down at any time by the military. Of course, as a radio receiver, it is susceptible to interference from strong RF signals at specific frequencies. Therefore pilots simultaneously use old-technology land-based systems like VHF omnidirectional range (VOR), radio-based distance measuring equipment (DME), nondirectional beacons (NDB) for redundant navigation. These three pieces of equipment use radio frequencies ranging from just below the AM band (NDB) to just above the FM radio band (VOR) to near one cell phone band (DME). Interference with one or two of these pieces of equipment isn’t a big deal. Some instrument cross-checking and a call to air traffic control would allow the pilot to identify the malfunctioning instrument. It would most likely be a brief distraction during a non-critical phase of flight.
Commercial aircraft carry collision avoidance systems that “talk” to the planes around them or use radar to measure distance to the ground. These systems go so far as to issue warnings and directions under a threat of a collision (“Pull Up, Pull Up!”). I doubt these systems would go so far as to give false directions on account of RF interference, but they could potentially be disabled by interference. That would reduce flight safety.
During an “instrument” landing numerous radios are employed that use frequencies all over the RF spectrum. First there is regular communications with air traffic control (near the FM band) on several different frequencies (center, approach, tower, ground). There are also a whole series of radios that get used (depending on the specific “approach” procedure being used) to precisely position the plane in three dimensions. A localizer (near the FM band) provides pilots with lateral guidance to the runway. A glideslope (using a 300 MHz band) directs the angle of descent to the runway. Marker beacons (at 75 MHz) tell pilots when they have reached certain landmarks in the landing process. The plane may use a radar altimeter to indicate height over terrain. And GPS may be used as well.
Interference with any of these radios during landing would probably be a non-issue because of the great redundancy in information and because pilots are trained to be risk averse. “Why the fuck is the glideslope bouncing like that!?! Tell the tower were going-around.” But with tens of millions of commercial flights taking place each year, even a small chance turns into the occasional crash.
So why do pilots get to use iPads in the cockpit? Because:
- Pilots can control them directly and quickly should an interference problem occur
- The iPad has been extensively tested for the potential to cause interference
- The benefit of better access to checklists, operations manuals (e.g. emergency procedures), and navigation information outweighs the potential problems of RF interference
None of these is true for the other one or two hundred other consumer electronics devices on the plane. Fire them all up, and there are now thousands of new RF signals on board.
It is impractical to test tens of thousands of consumer electronic devices to determine their potential to interfere with each of the 10 or so aircraft receivers used during a take-off or landing. And even if 99% of them “passed,” what would the FAA do about the remaining 1%? Suppose all Kindle’s are trouble-free, except the Kindle DX when the 3G transceiver turned on?
How do the logistics work for ensuring only non-interfering devices get used? They don’t. So we turn ‘em all off during the high-risk parts of the flight.