Ask the pilot

Are cellphones and laptops really dangerous to flight?


Patrick Smith
January 4, 2008 4:02PM (UTC)

Few rules are more confounding to airline passengers than those regarding the use of cellphones and portable electronic devices. Are these gadgets really hazardous to flight? And if so, why are the rules enforced so arbitrarily? I addressed this topic three years ago at the end of a column that ran over Christmas weekend. I doubt many people saw it. Because it's a subject that regularly draws media attention -- most recently in a segment on ABC's "20/20" -- as well as a steady stream of questions to my in box, it's time for a review.

Before getting to cellphones, passengers should know that the restrictions pertaining to computers, iPods and certain other devices have nothing to do with electronic interference at all. For instance, laptops. In theory, a poorly shielded notebook computer can emit harmful energy, but the main reason laptops need to be put away for takeoff and landing is to prevent them from becoming 200-mph projectiles in the event of an impact or sudden deceleration, and to help keep the passageways clear during an evacuation. Your computer is a piece of luggage, and luggage needs to be stowed so it doesn't kill somebody or get in the way.

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In the case of iPods and the like, it has to do with the headphones. During takeoffs and landings, you need to be able to hear and follow instructions if there's an emergency. That's hard to do if you've got your MP3 player cranked to 11. Similar to the requirement to raise your window shades, it's in the interest of situational awareness. A bit excessive? Maybe, and after all, flight attendants don't go around waking people up or quizzing them on evacuation procedures. But what the heck, it makes the cabin a slightly safer place, and it doesn't cost anything.

Now, as for cellphones. The million-dollar question: Can cellular communications really interfere with cockpit equipment?

The answer is potentially yes, but probably not. You want something meatier than that, I know, but that's about as accurate an answer as exists. Although cellular phones are unlikely to screw anything up, regulators are erring on the better-safe-than-sorry side.

Cockpit hardware and software use radio transmissions for a number of tasks. Whether transmitting, receiving or simply sitting idle, cellphones are able to garble these signals. As you might expect, aircraft electronics are designed and shielded with this interference in mind. This should mitigate any ill effects, and to date there are no proven cases where a cellphone has adversely affected the outcome of a flight. But you never know, and in some situations -- for instance, in the presence of old or faulty shielding -- it's possible that a telephone could bring about some sort of anomaly.

Notice that I say "anomaly" and not "flaming wreckage." You imagine some hapless passenger hitting the send button when suddenly the airplane explodes, flips over or nose-dives into the ground. In reality, should it occur, interference is liable to be subtle, transient and, in the end, harmless. People have a hard time grasping that every in-flight problem is not an impending catastrophe, and this is no exception. The electronic architecture of a modern jetliner is vast, to say the least, and most irregularities aren't exactly heart-stoppers -- a warning flag that flickers for a moment and then goes away, a course line that briefly goes askew. Or something unseen. I'm occasionally asked if I have ever personally witnessed cellular interference in a cockpit. Not to my knowledge, but I can't say for sure. Planes are large and complicated; minor, temporary malfunctions of this or that component aren't uncommon. Nine times in 10, what brought about that fleeting glitch is never known.

Having said that, cellphones may have had a role in at least two serious incidents. Some blame a phone for the unsolved crash of a Crossair regional plane in Switzerland seven years ago, claiming spurious transmissions confused the plane's autopilot. In another case, a regional jet was forced to make an emergency landing after a fire alarm was triggered by a ringing phone in the luggage compartment. There have been other, anecdotal reports of varying seriousness, but none can be definitively linked to telephones.

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Even if not actively connected, a cellphone's power-on mode dispatches bursts of potentially harmful energy. For this reason, all phones must be placed in the proverbial "off position" prior to taxiing. This is usually requested at the beginning of each flight as part of the never tedious pre-takeoff safety briefing. The policy is clearly stated, but unenforced. We assume the risks are minimal, or else the airlines would collect phones rather than relying on the honor system. I would venture to guess that at least half of all cellular phones, whether inadvertently or out of laziness, are left on during flight. That's about a million phones on about 10,000 flights every day, just in the United States. If indeed this were a recipe for disaster, I think we'd have more evidence by now.

In late 2004, USA Today ran a front-page story about a proposed relaxation of the cellphone ban. The article prompted millions of Americans to wonder if the rules were ever necessary in the first place. In the days that followed, flight attendants across the country dealt with insubordinate fliers who refused to put phones away when asked, and cynics wondered if maybe there wasn't some conspiracy afoot. Was the whole thing a ruse from the beginning, designed to encourage passengers to splurge on those pricey seat-back satellite phones? Another theory holds that the ban was enacted at the behest of wireless providers. Without it, they would lose millions of dollars because calls made while aloft are untraceable and callers cannot be charged.

That second one isn't quite correct, but it has some merit. In America, the existing restrictions were laid out in 1991 by the FCC, not the FAA. Calls placed from fast-flying aircraft tend to jump from antenna tower to antenna tower, resulting in various technical problems for the communications companies. This is entirely separate from, and does not negate, the interference issues.

Meanwhile, if ever there was a satellite phone conspiracy, it was a failure from the start. When was the last time you actually saw anybody use one of those damn "Airfone" things? I've logged my share of miles, believe me, and only once did I ever place a call from my seat -- in 1991. I'm fairly certain I've never seen anybody else do it. Many airlines have been gradually removing satellite phones from their aircraft.

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Another idea suggests that airlines are using the mere possibility of technical complications as a way of keeping the cellphone debate off the table. For better or worse, the minute it can be proved beyond reasonable doubt that doing so is harmless, a certain percentage of fliers will begin demanding to use them. The result will pit one angry group of travelers against another, with carriers stuck in the middle.

If indeed airlines are playing this game, count me among those who hope the prohibition stays in place -- not out of technical concerns, but for the sake of human decency and some bloody peace and quiet. The sensory bombardment inside airports is overwhelming enough -- incessant public security admonishments; the unintelligible howling of gateside public address announcements; the ubiquitously blaring CNN Airport News. For me at least, colic-stricken infants and the safety demo notwithstanding, the airplane cabin is a last refuge of relative silence. Let's keep it that way.

Alas, I fear the regulations are destined to change at some point, and cellphone use will become commonplace at 35,000 feet.

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Currently under trial is an onboard communications system that is able to collect and retransmit cellular signals by way of a laptop-size server and a series of small base stations, called "picocells," spaced throughout the passenger cabin. Weighing about 20 pounds, a picocell automatically commands your phone to operate at greatly reduced power. Calls are then routed to ground stations one of two ways -- via satellite, or directly using special towers and a dedicated frequency band. This should eliminate both the cockpit interference hazard and the tower-to-tower signal bouncing that, for the time being, make high-altitude calling impossible.

Heaven help us. Perhaps we can have "chattering" and "non-chattering" sections, akin to the old smoking and nonsmoking.


Do you have questions for Salon's aviation expert? Send them to AskThePilot and look for answers in a future column.

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Patrick Smith

Patrick Smith is an airline pilot.

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