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Mobile Phone Interference on Airplanes: Myth or Reality?

AirplaneDuring a recent speaking event at the University of Wisconsin-Eau Claire, one of the questions Hardware.com staff were repeatedly asked was whether mobile devices, such as smartphones, tablets, and computers, actually affect airplane communications. It’s a great question, and one many of us have pondered over the years, particularly as engineers.  As one blogger put it, “If electronic gadgets were able to interfere with airplane communication and navigation systems and could potentially bring down an airplane, you can be sure that the Department of Homeland Security wouldn’t allow passengers to board a plane with a mobile phone or iPad, for fear that they could be used by terrorists.”

Interestingly, depending on whom you ask it appears the answer about whether mobile devices affect airplane communications is still up in the air—no pun intended. According to The New York Times, the Federal Aviation Administration (FAA) has no proof that a phone or tablet can (or cannot) interfere with the operation of a plane. So why the ban?

The Discovery Channel explains that when a passenger makes a call at 10,000 feet, the signal bounces off multiple available cell towers, rather than one at a time. The frequent switching between towers creates significant overhead on the network and may clog up the networks on the ground. Hence why the Federal Communications Commission (FCC)—not the FAA—banned the use of cell phones on planes.

Another theory, discussed on the EDN Network by systems engineer and security architect Mohit Arora, has to do with possible electromagnetic interference to aircraft systems. Arora writes of active radio transmitters (mobile phones, small walkie-talkies, etc.):

Technically speaking, the more turns of wires you have around any substance (iron core, carbon core, or simply air core), the more it amplifies the force of a ‘radio wave’s’ effect upon any single electron. In other words, the radio waves from a cell phone push electrons along that coil with increasing force, thus affecting the measurement. Galvanometers—[instruments used to detect and measure electric currents]—have a large number of coils and a very small gauge of enameled copper wire and are extremely sensitive to small electromagnetic stimulus.

However, Arora then points out that many galvanometers have been replaced by new technologies, which he assumes have good shielding. He also points out that “since a large number of old planes are still in service, their tolerance to electromagnetic radiation could degrade over time unless repaired and serviced from time to time.”

Despite the lack of evidence that mobile devices affect airplane safety, a lot of reports cite mobile devices for potential electronic interference. In 2011, ABC News reported a study from the International Air Transport Association (IATA) that documents 75 separate incidents that airline pilots and other crew members believed were linked to mobile phones and other electronic devices. According to the report, 26 of the incidents affected the flight controls, including the autopilot, autothrust, and landing gear, 17 affected navigation systems, and 15 affected communication systems.

However, the report above and all other reports on cell phone interference are based purely on speculation. Many airlines, such as American Airlines and Delta, offer passengers in-air Wi-Fi service after reaching 10,000 feet. In fact, CNBC recently reported that Delta—considered by many to be a leader on the Wi-Fi front in the USA—offers passengers free Wi-Fi on more than 800 aircraft, many of which are regional. Although the free access is mostly limited to shopping deals, breaking news, and flight information, Delta passengers can gain full internet access by purchasing a Gogo® internet package prior to boarding.

Amid increasing public skepticism, the FAA finally announced last October that it would begin reviewing its policies on the use of electronic devices during all phases of flight, including takeoff and landing. Until then, with no evidence to prove that using mobile devices on airplanes is safe or unsafe, passengers are well advised to follow the FAA’s guidelines until further notice.

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