ALTOM: Why can't we use cell phones on a plane?

October 24, 2009

Who among us hasn’t pondered life’s great questions? Why are we here? Why aren’t we somewhere else? Why do some people never learn how to parallel park?

And perhaps most mysterious of all—is it true that operating electronic devices on a plane may cause it to go out of control and crash? Perhaps surprisingly, the answer is that nobody really knows. The many regulations surrounding them appear to be a combination of informed guesswork and understandable paranoia.

Let’s start with the fundamentals. All modern aircraft rely on a wide array of electronics to get them through the skies. But most systems have backups and all are shielded from electromagnetic interference. Most of today’s consumer gadgetry radiates some kind of EMI. Laptops certainly do, both from their internal “clocks” and from their constantly sniffing WiFi. Some music players do in small amounts. Cell phones function by emitting radiation. Is all this stuff harmful to the plane’s electronics? And if so, why are they often permitted in-flight, but banned during takeoff and landing?

Of all consumer devices, cell phones cause the greatest concern. Cell phones are banned on domestic flights, not primarily because of the FAA or the airlines’ fretfulness, but because of FCC regulations. Cell phones operate with “channel reuse.” Phones all use the same frequency, but they communicate with only one tower at a time. You get handed off from tower to tower as you move around. Generally speaking, you’re never equidistant between several towers, which could gobble up too much of the channel as they compete for your signal. But flying over a major city, the FCC figures you could simultaneously engage several of those towers, leading to chaos and severe channel overuse. If the FCC has actually tested this, I haven’t been able to find any evidence of it.

Other countries, among them Mexico and Ireland, have decided to permit use from planes. U.S. airlines still have to make do with special airline phones provided for passenger use. Cell-phone companies appear to be the biggest fans of the in-flight ban, but they chafe when airlines won’t let passengers use their phones while taxiing.

If the aircraft isn’t in American skies, you still can’t use your cell phone, because then the FAA regulations kick in. Those regulations ban the use of any personal electronic devices, but then the FAA passes the buck to the airlines by saying the airline can permit the use of any device the airline has determined to be safe. The FAA also explicitly excludes from its restrictions portable voice recorders, hearing aids, heart pacemakers, and electric shavers.

But what makes the FAA sure our everyday devices are dangerous? As it turns out, largely nothing. Multiple studies have shown no demonstrable effect of cell phone or other radiation on airplane electronics. There is plenty of anecdotal evidence. Flight crews are constantly noting anomalies in their on-board electronics, and they usually ascribe them to the use of personal electronic devices. Boeing decided to study the problem and bombarded test aircraft with devices which were blamed for causing the anomalies, but was never able to reproduce them in test conditions.

In fact, it seems no one has been able to do so consistently. Airplanes fly through a fog of potential interference, from radio and television signals to cell frequencies. It’s hard to pinpoint the cause of any particular blip. It’s indisputable that personal devices emit radiation, but whether it causes malfunctions is still an open question.

Still, flight crews remain nervous. The FAA passes the buck to the airlines, and the airlines in turn let the air crews clamp down even harder if they want to. Flight attendants aren’t electronic engineers and all they know is that they want to get the flight over with and get home, so any potential threat is there only to be neutralized. Flight attendants routinely ask iPhone users, for example, to turn off the devices, even though the iPhone features an “airplane mode” that switches off all radio activity but keeps the rest of the phone’s functionality active. They don’t want to hear about the iPhone’s feature set, only that it’s entirely off.

There are even conspiracy theorists who say the ban on cell phones in particular is suspicious, because the airline gets a cut of the air-phone usage. There is also apprehension that the ban is welcomed because a plane full of overly loud cell-phone chatter would be intolerable.

It might be wise during takeoffs and landings to put away objects that could turn into deadly debris during an emergency. But as our flying experience comes ever closer to resembling the old Soviet aviation system, it’s discouraging to know that, once again, policymakers are apparently shooting from the hip.•


Altom is an independent local technology consultant. His column appears every other week. He can be reached at taltom@ibj.com.


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