How does Flight Mode work?

Summer is here (allegedly), and millions of Brits are about to embark on long-awaited holidays abroad or to far-flung corners of the United Kingdom.

This generally means boarding a plane, in turn necessitating cabin crew announcements that mobile devices must be turned off or set to flight mode (also known as airplane mode).

If you’ve never delved too deeply into your handset’s settings menus, this might be perplexing.

After all, ship’s captains don’t request we put our devices in ‘sail mode’, even though modern cruise ships are even more mechanically complex than most aeroplanes.

However, there are specific reasons why phones on planes aren’t a good idea – for now, at least.

It’ll be all flight on the night

With a single tap on the plane logo in your device’s pull-down settings menu, any radio frequency signal transmissions to and from the handset are prevented.

That includes Bluetooth, WiFi and mobile network connectivity including voice/data transfers. GPS may also be deactivated, though this is device-specific.

The phone is effectively disabled as a communications tool. It’s still able to take pictures, play downloaded media content and support apps which work offline.

Why is this necessary?

Historically, the radio waves used to transmit data to and from phones had potential to interfere with the delicate sensors and navigation equipment used by aeroplanes.

There were concerns that electromagnetic interference could affect the pilot’s ability to communicate with operators on the ground, or use certain instrumentation.

Of course, some people dismissed this as an urban myth, akin to the rumour using a mobile phone in a petrol station could cause an explosion at the pumps.

And it seems the cynics might have been correct.

There’s minimal evidence that using a phone’s cellular connectivity mid-flight could pose a safety risk, or affect the plane’s navigation and communication equipment.

Some airlines now offer in-flight WiFi for surfing and gaming (though rarely streaming) once the plane has reached an altitude of more than 10,000 feet.

Most carriers allow Bluetooth to connect devices like wireless headphones, as Bluetooth’s range is too short to affect the cabin. A few firms even permit mid-flight phone calls.

Different airlines have unique rules laws regarding safe phone usage, while national laws are also evolving in different – and sometimes directly contradictory – ways.

In America, the FCC has outlawed using phones while off the ground, despite also permitting the use of any electronic devices which individual airlines believe won’t cause interference.

Just to make matters even more confusing, certain smartphones are capable of having both WiFi and Bluetooth activated while airplane mode is on.

What should I do on a plane?

It’s always better to err on the side of caution, so we’d recommend engaging flight mode before buckling your seatbelt and watching the safety briefing.

If your phone permits WiFi or Bluetooth in airplane mode, you’ll be able to use peripherals and access the plane’s on-board data network as normal.

If it doesn’t, and you need to use either Bluetooth or WiFi, ensure mobile data is deactivated to eliminate interference from GPS or call connectivity signals.

(Turning your phone to airplane mode substantially extends battery life – ideal for long flights where USB or power sockets may not be available.)

You’re unlikely to receive any network service mid-flight, so turning off mobile data shouldn’t be unduly inconvenient.

Tripping the light fantastic

Feature-disabling flight modes may be eradicated soon by a new method of mobile data connectivity called Light Fidelity.

This involves using an LED bulb’s two states – off and on – as a type of binary data transfer. Turning the light on and off incredibly quickly can rapidly distribute digital data.

LiFi harnesses the high-frequency short-wavelength Visible Light Communications spectrum for data transmission, instead of the congested radio frequency spectrum presently in use.

Because LiFi is blocked by solid objects including doors, data transmissions within an aircraft cabin wouldn’t leak through into the cockpit in the way GHz radio wave signals can.

And because any LED is capable of distributing data to a suitable receiver, every overhead reading lamp or aisle spotlight could be used to provide passengers with mobile data.

This technology is still a few years away, but LiFi might mean tomorrow’s phones and tablets won’t need an airplane mode to be safe travel companions on overseas excursions.