Before every flight there’s an announcement telling you to switch off all portable electronic devices and cell phones. I’ve heard this announcement countless times and I usually obey it. The announcement may or may not include a notice saying that you may use electronic devices again once at cruising altitude, but only if they’re not generating a cellular signal or other such radio waves. For most modern devices like cell phones, you have an Airplane Mode option which kills off any dangerous emissions and limits your device to basic offline capabilities. With in-flight WiFi now a possibility, the warnings regarding the dangers of electronic devices on airplanes has become all but a moot point in modern air travel.
However, a recent confidential study by STEADES, the aviation industry’s safety incident data management and analysis program, shows that there is a strong correlation between personal electronic devices and instrument anomalies that occur during flights. The STEADES report says that there were 75 reported cases where cell phones or other electronic devices were linked to such events.
How can your cell phone affect the instruments in an airplane’s cockpit when you’re stuck between a smelly person and a crying baby all the way back in seat 46B in Coach? It turns out that a lot of sensors and equipment that are directly related to the instrument panel in the cockpit are hidden in the passenger cabin. For example, sensors used in an instrument landing system that engages during bad weather exist in the passenger area. Signals from electronic devices can interfere with those sensors, and if the interference happens at the right place at the right time, it may spell out trouble, or even disaster for the flight.
On one flight the autopilot suddenly disengaged and warning lights came on. The pilot sent the flight attendants through the passenger cabins to look for any electronic devices that were on. After identified four instances of passengers using electronic devices, the flight attendants informed the passengers to turn them off and the instrument panel in the cockpit began to work normally once more.
ABC News obtained this report and asked Boeing to demonstrate whether or not certain electronic devices were a threat to airline safety. Boeing has a certain frequency threshold that it considers acceptable for electronic devices, meaning your devices are OK to use on flights as long as the radio waves or other signals they generate fall below that threshold. The threshold involves both megahertz as well as decibel-millivolts and both a Blackberry and an iPhone frequently spiked above the threshold. Surprisingly, the iPad was said to be the worst offender as its average clock circuitry was almost always above the threshold.
However, the STEADES study does not confirm that cell phones and personal electronic devices are the cause of these instrument anomalies. In fact, this report is to be taken with a grain of salt as many aviation experts say that if an airplane’s electronic systems are properly sheathed then cell phone or iPod interference becomes a non-issue. Although proper sheathing is present in newer airplanes, there are many airplanes in service that are older and do not have those precautions in place. This is why in-flight WiFi is only available on the newest model airplanes that have appropriate shielding in place for their instruments. Electronic sheathing is not a federal regulation so it will take time before all aircraft are properly protected from any signal interference that comes from our gadgets. For now, your best bet is do keep those devices off, especially if you’re on an older model airplane.