Modern cell phones emit different types of electromagnetic waves such as WiFiBluetooth, mobile data, NFC (for proximity communications, such as digital wallets) and GPS. When flying in an airplane, these technologies can emit waves that, if they operate in the same frequency bands used by the aircraft’s navigation and communication systems, can cause interference, especially in critical phases of the flight, such as landing and takeoff.
This is why, during a plane trip, passengers must set their cell phones to flight mode, which disables all transmissions and reception of wireless signals from the device. With “airplane mode” activated, the cell phone is completely offline.
Airplane mode on your cell phone disables the emission and reception of electromagnetic waves, leaving the device completely disconnected Photograph: Ben Stansall/BEN STANSALL
Although airplane mode limits the arrival of online notifications, it will not prevent your cell phone from issuing offline alerts that you program, such as your alarms. Therefore, in a cinema or play, in addition to activating flight mode, ideally you should also put your cell phone in silent mode.
By disabling your connectivity features, airplane mode also ends up preserving your cell phone’s battery, being a useful option when you need to be far from a charger and need to keep your cell phone on.
What happens if I don’t turn on airplane mode during a flight?
Contrary to popular belief, you don’t run the risk of crashing the plane just by taking your cell phone out of flight mode, but doing so could impair the aircraft’s communication with the control towers.
There is also concern that interference caused by electromagnetic waves from cell phones could cause the loss of important flight information such as speed and navigation data. That’s why it’s important to keep your device offline during your commute.
But how does the plane offer Wi-Fi during the flight?
Airplanes are able to offer Wi-Fi without interfering with in-flight communications through technologies designed to prevent such interference. One of them is through connections via terrestrial transmission towers. When the plane is flying over areas covered by transmission towers, it uses antennas located in the lower part of the fuselage to capture the Wi-Fi signal from these towers, in a similar way to signal reception by devices on the ground. In areas where there are no towers, such as over oceans, the plane can use satellites to maintain the connection.
One Anac regulation says that airlines are responsible for providing the necessary security so that the Wi-Fi offered during the flight does not interfere with the operation of the plane’s equipment and its communication with the control towers.
In any case, the signal is only released to passengers during periods of stability and outside critical moments, such as takeoff and landing stages.
