Fasten your seat belt, raise your tablet and cut the connection to the 4G networks on the ground.
When flying, asking flight personnel to switch to Airplane mode may seem anachronistic today, even as devices are increasingly connected, and while other connections, Bluetooth and wi-fi, are active.
It is no longer mandatory since 2014 to turn off your phone or switch it to Airplane mode on takeoff, and the European Aviation Safety Agency has left the last word to airlines who choose their commercial policy on board. .
So why do they continue?
No, they do not favor their paid Wi-Fi networks to the detriment of our mobile Internet subscriptions.
They simply apply the precautionary principle and just limit the risk of electromagnetic wave interference with the aircraft controls.
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In normal mode, smartphones indeed request the networks of the 3 or 4G antennas transmitting on the ground for a data exchange.
Airplane mode cuts off the more intense search for networks during a flight at high altitude and the massive sending of waves.
"This would induce the propagation of signals in the environment of the aircraft whose characteristics such as frequency, waveform or power could be such as to disturb its systems/equipment", specifies the Directorate General of the Civil aviation (DGAC).
Radio interference for pilots
A single oversight would not be enough to disrupt the flight, but massive use of a network to watch streaming videos could disrupt the aircraft's antennas.
Clearly, the waves looking for an antenna to connect to could reduce the quality of the radio signals used by pilots to communicate with air traffic controllers.
"The electromagnetic waves can also disturb the electronic controls of the plane which pass through cables but recover part of the electrical energy from the surroundings", points out Éric
Fournier, director of international affairs at the National Frequency Agency (ANFR).
There were, however, no crashes officially attributed to smartphone use.
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What about the wi-fi connections offered on the most recent planes thanks to satellite Internet?
Potentially problematic, its use is also regulated.
"The connectivity offered on board by certain companies was the subject of a certification during which it was demonstrated that the "ecosystem" at work does not impact the operation of the aircraft's equipment" specifies the DGAC.
Finally, another wireless signal, Bluetooth, presents very little risk.
“It is on the same frequency band as the historic wi-fi”, recalls Éric
ANFR's Fournier "but with a power ratio of 1 to 100 Milliwatts so interference with aircraft systems is almost impossible even with an accumulation of passengers using Bluetooth".