What Happens If You Don’t Put Your Phone on Airplane Mode on a Flight?

You hear the warning every time you fly: Please set all devices to airplane mode. But what happens if you don't?

It’s not that long ago that airlines stopped telling passengers to keep their mobile phones, tablets, e-readers and other devices turned off throughout the flight. 

Why Airplane Mode. We’re asked to turn our devices off or to put them in Airplane Mode because of electromagnetic interference from phones, tablets, e-readers, electronic headsets, and more. Since some planes were built before these became a thing, it took a while for the industry to make sure it was entirely safe to use them.

These days, you’ll even see iPads and other tablets in the flight deck, which pilots use to store paperwork instead of lugging around big bags with actual paper in them. You’ll see flight attendants using tablets and big phones too, either instead of or in addition to those reams and reams of dot-matrix printed paperwork. All those devices have been tested extensively to make sure there’s no interference.  

That testing happened during the rigorous qualification process to enable airlines to offer inflight internet. Part of that testing process is creating enough electromagnetic interference to represent an entire cabin full of devices of a variety of sizes, including some that are malfunctioning. Pretty much every airliner-equipment combo operated by a major international airline has now been tested.

So, what happens if I don't put my phone on airplane mode? 

For years, safety regulators, airlines, aircraft manufacturers, and everyone else in the industry has known that there are dozens of devices left out of airplane mode on every flight. In a way, the fact that planes haven’t fallen out of the sky willy-nilly because someone left their Kindle on is the best demonstration that, for the most part, most devices don’t affect most planes.

But “most” isn’t good enough for aviation. Some folks don’t know that their Kindle even has 3G, or that the Bluetooth on their watch or headphones or other device counts as needing to be put into airplane mode. Some forget that they’ve packed one of those devices in the overhead bin. Some even blatantly ignore the rules, assuming that their vital email on that BlackBerry isn’t going to make their plane start to plummet. And it probably isn’t. 

The real reason to be sure your phone is put into Airplane Mode is to be sure that you don’t accidentally connect to the in-flight roaming network and get billed for time on that network. This is also true if you are in a foreign country. Airplane Mode keeps your cellular devices from roaming on a local network which could generate huge charges depending on how long you are in-country. That’s also true for cruises.

The other big reason to use Airplane Mode while on aircraft is that the effort your cell phone goes through to keep scanning and tower hopping at fly-by speeds can drain your battery in a big way.

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