Mobile Phones on Airplanes: Too Soon to Talk?

To some airline passengers, a mobile phone is God's gift to air travel. You can see how eagerly they relieve the boredom of watching other passengers struggle into their seats by chatting with friends and relatives until the last possible second—and sometimes longer. I've watched the test of wills as a flight attendant stood by an oblivious businessman who simply would not put up his phone until she repeated her request three times and threatened to delay the flight for everybody. And it sometimes looks like a contest to see who can whip out their phone and make the first call after the announcement that it's okay to use phones again after landing. Clearly, people would like to use their mobile phones all the time, not just on the ground. Possibly in view of this fact, the Federal Communications Commission has announced that it is considering whether to lift the restriction on in-flight mobile phone calls. So is there anything to the notion that electronic devices such as mobile phones can seriously affect the avionics of a modern jet aircraft? Or is it just a silly bureaucratic exhibition of meaningless power without foundation in fact?

Sources: An online version of the March 2006 IEEE Spectrum article, "Unsafe at Any Airspeed," is at http://www.spectrum.ieee.org/mar06/3069.

Surprisingly little research has been done into whether people actually use mobile phones on plane flights, and if such use can interfere with navigation or communication systems. In the March 2006 issue of the magazine IEEE Spectrum, a publication for professional electronic engineers, researchers at Carnegie Mellon University reported the findings of a three-month investigation in which they placed a radio-wave "sniffer" on board numerous commercial flights. This instrument package was designed to receive and record radio emissions in the frequencies used by mobile phones. After the equipment flew in the overhead luggage rack on 37 different commercial flights, the data was downloaded and analyzed.

It turned out that on average, at least one person on every flight, and sometimes several people, made one or more mobile phone calls at times that clearly violated FAA and airline rules. While none of the planes in the study crashed or reported any harmful interference with avionics, the researchers found from independent data collected by NASA that there have been over seventy incidents in which portable electronic devices on board a plane have interfered with aircraft systems. The increasing use of global positioning system (GPS) navigation tools makes newer avionics even more vulnerable to interference than in the past, since GPS relies on receiving weak satellite signals that can disappear under interference from onboard phones, laptops, or other unauthorized electronics. While the Carnegie Mellon study does not cite a particular plane crash as being caused by interference from portable electronic devices, it implies that interference may have contributed to crashes in the past, given what we now know about mobile phone use on airliners.

Based on the results of their study, the researchers made several recommendations. A total ban on mobile phones in airplanes was not one of them. One of their most innovative proposals is to equip flight crews with a hand-held version of their "sniffer." This could be made as small as a pager and could be slipped into a pocket. At the same time that the flight attendant offers coffee, tea, or snacks, he or she could be patrolling the aisles for illicit mobile-phone use. Simply warning passengers that any mobile phone use can be detected in this way would probably go far toward discouraging the practice.

Other recommendations include better coordination between the Federal Aviation Administration, in charge of airline safety, and the Federal Communications Commission, in charge of the airwaves. Also, the NASA program that accumulated data about airline safety problems has had its budget cut in recent years, and the researchers called for its funding to be restored. All of these ideas are good ones, but unless politicians, industry representatives, and regulators take action, things may go on as they are until a tragedy occurs.

Tragedies are, unfortunately, great motivators for regulators and politicians to do something. The trouble with the interference problem in this regard is that, unlike a broken turbine blade or other physical cause, radio interference leaves little or no trace of itself after a crash. Even if a crash was caused by interference that produced a false reading from a GPS display, discovering this cause after the fact would be difficult or impossible without much better in-flight data recording than we now have.

So this is one problem that may be difficult to fix technologically. Of course, if everybody followed the rules, it would disappear. And here is one instance where you, the individual airline passenger, can do something. Not only can you refrain from using your mobile phone during prohibited parts of the flight, but if you see someone else doing it, you might try speaking to them about it. The life you save may be your own!