Why Do You Have to Turn Off Electronic Devices on an Airplane?

Mobile telephones, tablets, portable video game units, and other electronic devices are ubiquitous 21st-century time killers. We can play games on them, communicate with family and friends on them, and browse the Internet on them. One would think that they would come in very handy to pass the time during a multi-hour airplane flight, where movement from one’s seat is discouraged. However, those of us who have flown during the past decade are familiar with the preflight reminder to turn off all electronic devices or keep them in “airplane mode” (or “flight mode”) during the entire flight. We are warned that cellular service must be turned off because device transmissions interfere with the aircraft’s navigational equipment. But does this really happen? Can your cellular phone or other electronic device truly endanger the flight?

The short answer to this question is probably not, but you should probably know how your electronic device affects the plane’s instruments as well as other passengers during the flight.


The first step is knowing how your electronic device works and interacts with the airplane. Generally speaking, in order to connect to a wireless network or cellular telephone tower, electronic devices become low-power radio wave transmitters (that often max out at 0.25 W in the case of mobile phones) that link to cellular towers and other receivers that carry the signal outward—but they also become receivers to receive inbound signals. If the tower or other receiver is relatively close by, the device does not have to use as much power to search for the tower’s signal and maintain the signal between the tower and the device.

When an electronic device is in active or cellular mode, it sends out a radio signal, but when it is in airplane mode, it does not. Most airlines note that there is a chance that radio signals sent out from an electronic device could interfere with one or more of an aircraft’s important systems, such as sensors that help the aircraft’s instruments communicate with one another, navigation equipment, collision-avoidance equipment, and other forms of avionics.