Personal mobile devices could act in a similar way on aeroplanes, on which hundreds of electronics-based systems, known as avionics, are used for navigation, to communicate with the ground and to keep track of the components that keep them in the air.
Some involve sensors that communicate information to cockpit instruments. It's not just an issue with mobile phones. Kindles, iPods, laptops, handheld gaming consoles — they all emit radio waves. If these are at frequencies close to those of the avionics, signals and readings could be corrupted. This could affect systems such as radar, communications and collision avoidance technology, and the problem is potentially magnified if gadgets are damaged and start emitting stronger radio waves than they should, or if signals from multiple devices combine.
So much for the theory, but is there any proof that this is a problem? There are no known recorded incidents of crashes having been definitely caused by such interference, but that said the causes of accidents can sometimes remain unknown.
But while definite proof may be lacking, there is plenty of anecdotal evidence that the risks should be taken seriously. A report summarising 50 cases of safety issues thought to have been caused by personal electronic devices, was published in January this year. These were compiled from the US Aviation Safety Reporting System, a database maintained by Nasa, to which crew members can anonymously submit reports of safety problems. One such case was summarised as follows: "First Officer reports compass system malfunctions during initial climb.
When passengers are asked to verify that all electronic devices are turned off the compass system returns to normal. A analysis of the database identified reports of interference from electronic gadgets, of which 77 were defined as "highly correlated". In one incident a degree error in navigation equipment was immediately corrected when a passenger turned off a portable DVD player.
This problem reoccurred when the device was switched back on. Well, sort of. You could actually be charged with two offenses. Of course, those outcomes are mostly referring to passengers who are willfully refusing to switch their phones into airplane mode.
And the safety concern among passengers has actually made vigilantes of us all, Laurie says, based on his experience as a flight attendant. All the regulations in the world still haven't prevented airline passengers from casually whipping out the cell phone every now and then. About one to four cell phone calls were made during every commercial flight, according to a study from Carnegie Mellon University in Pittsburgh.
Funnily enough, the FAA even had to advise aircraft crewmembers to turn off their cell phones during takeoff and landing, after an incident in early In that case, a first officer's ringtone proved potentially distracting during takeoff — but as the crew pointed out, their General Operations Manual did not prohibit them from keeping their cell phones on.
Travelers who can't part with their wireless Internet connections can now at least pay for in-flight access on a growing number of airlines, or take advantage of a free Wi-Fi holiday deal on Virgin American flights. Such services use a dedicated chunk of the electromagnetic spectrum reserved for air-to-ground communication. Cell phone use remains out of the question during flights, and ditto for Internet voice applications such as Skype.
But passengers can at least comfort themselves by knowing that their flight won't include anyone yammering loudly on a personal call. As the FAA notes, a majority of travelers probably prefer the silence.
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