By: Bill Strauss, M. Granger Morgan, Jay Apt, and Daniel D. Stancil
Cellphones and Other Electronics Are More of a Risk Than You Think
IEEE Spectrum
March 2006
Is it safe to use cellphones on airplanes? The U.S. Federal
Communications Commission (FCC) thinks it may be. In December 2004,
the agency began soliciting comments on proposed regulations that
would allow airline passengers to use cellphones and other electronic
devices. To be sure, it acknowledges that a sister agency, the Federal
Aviation Administration (FAA), has ultimate authority regarding
regulations that govern airline safety. Yet a July 2005 report by a
U.S. House of Representatives subcommittee, which held hearings on the
matter, noted: "The FCC hopes to issue a final ruling in 2006, stating
that its ultimate objective is to allow consumers to use their own
wireless devices during flight."
In the meantime, more and more passengers are bringing cellphones,
PDAs, laptops, DVD players, and game machines on board. All of these
items emit radiation and have the potential to interfere with aircraft
instrumentation. More and more passengers, however, do not believe
that using portable electronic devices presents a risk to their
safety. We, on the other hand, have had our doubts that such use was
safe.
Over the course of three months in late 2003, we investigated the
possibility that portable electronic devices interfere with a plane's
safety instruments by measuring the RF spectrum inside commercial
aircraft cabins. What we found was disturbing. Passengers are using
cellphones, on the average, at least once per flight, contrary to FCC
and FAA regulations, and sometimes during the especially critical
flight phases of takeoff and landing. Although that number seems low,
keep in mind that it represents the furtive activity of a small number
of rule breakers. Should the FCC and the airlines allow cellphone use,
the number of calls could rise dramatically. In addition, regulations
already permit a wide variety of other portable electronic
devices-from game machines to laptops with Wi-Fi cards-to be used in
the air today. Yet our research has found that these items can
interrupt the normal operation of key cockpit instruments, especially
Global Positioning System (GPS) receivers, which are increasingly
vital to safe landings. Two different studies by NASA further support
the idea that passengers' electronic devices dangerously produce
interference in a way that reduces the safety margins for critical
avionics systems.
There is no smoking gun to this story: there is no definitive instance
of an air accident known to have been caused by a passenger's use of
an electronic device. Nonetheless, although it is impossible to say
that such use has contributed to air accidents in the past, the data
also make it impossible to rule it out completely. More important,
the data support a conclusion that continued use of portable
RF-emitting devices such as cellphones will, in all likelihood,
someday cause an accident by interfering with critical cockpit
instruments such as GPS receivers. This much is certain: there exists
a greater potential for problems than was previously believed.
Although our data are more than two years old, they still represent
the best available in this critical area of air safety. Ours is the
first documented study of in-flight RF emissions by portable
electronic devices and, we believe, the first such scientific
measuring other than what has been done by individual airlines. And as
far as we know, it is the first in-the-field examination ever into the
critical question of emissions interference with the spectrum bands
used for navigation. Yet despite the paucity of available data,
regulators and the airlines seem poised to yield to public demands to
allow the use of cellphones in flight and the use of other devices,
such as PDAs, during critical phases of flight. We believe additional
studies are needed to characterize potential risks, followed by
regulations that ensure the safe use of radiating devices, and we
conclude with a suggested five-point program for such studies. And we
argue that in the meantime, the public needs to be more clearly
informed about the risks of its current behavior.
http://www.spectrum.ieee.org/mar06/3069
Monty Solomon (monty@roscom.com)