Airlines may ask passengers to activate airplane mode on their smartphones. A practice as old as mobile telephony itself, it aims to avoid interference. But what is it really, and what are the risks? We'll explain everything to you.
The famous YouTuber Mark Rober has just published a short video on airplane mode, which airlines still require to be activated on smartphones once on board. It is indeed surprising that this instruction is still often imposed on passengers in 2025, especially on modern aircraft.
For their part, passengers rarely understand the potential impact of forgetting to activate airplane mode on their mobile. The problem remains, in reality, above all a risk linked to the allocation of frequencies dedicated to mobile networks and those linked to aviation in certain countries. Above all, there is the risk of distorting the measurements taken from a piece of equipment: the radio altimeter.
Why airplane mode is necessary... in some countries
In the United States, the frequency ranges allocated to mobile operators directly border those used by aviation. The 3.7-4.2 GHz band is allocated to mobile networks, while the 4.2-4.4 GHz range is used for aviation. It is the lack of space between these two frequency ranges that causes the American aviation regulator, in particular, to fear interference. This further justifies this obligation to use airplane mode.
According to the YouTuber, the risk is increased when several "poorly adjusted" terminals emit in frequencies close to 4.2 GHz. Particularly during maneuvers where pilots absolutely must refer to their altimeter data. The problem is, however, less of a problem in Europe, where the bands dedicated to aeronautics and those dedicated to mobile networks are now much more spaced apart.
This is why the European Commission recently decided to authorize airlines to no longer require passengers to switch to airplane mode. While also authorizing them to install 5G antennas at onboard, allowing continuous access to the mobile network, even in mid-flight. The news doesn't make everyone happy. On the one hand, it's rather pleasant, a priori, to be able to continue browsing the internet during a trip.
On the other hand, some fear that passengers will take advantage of this to make noisy calls, which could degrade the experience of other passengers.
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