Mobile Fundamentals · Cellular Networks · Lesson 2 of 4

Airplane Mode & Radios

Flip the switches yourself and see which radios go dark.

Flip the switches

A phone is packed with radios. The main ones are cellular (for calls, texts and mobile data), Wi-Fi and Bluetooth. Each one sends and receives radio signals.

Airplane mode is a single switch that turns all of these off at once. It was made for flights, but it's handy anywhere you want the radios quiet or need to save battery.

Once airplane mode is on, you can turn Wi-Fi and Bluetooth back on by themselves. That's how people use in-flight Wi-Fi or wireless earbuds on a plane. Many phones remember this and turn them back on automatically next time. Cellular works differently. It stays off until you switch airplane mode off, so the phone can't talk to any tower.

This matters for investigations. A phone in airplane mode won't connect to its carrier, so it leaves no new trace in the carrier's records. With Wi-Fi on, though, it can still send messages and sync photos over the internet.

On the simulated phone, turn on Airplane mode, then turn Wi-Fi back on. Watch the radio status panel.

What about GPS?

GPS works differently from the other radios. GPS satellites constantly broadcast timing signals. Your phone's GPS chip listens to several of them and works out its position from how long each signal took to arrive. It never sends anything back, so the satellites have no idea your phone exists.

Because GPS is receive-only, most modern phones leave it working in airplane mode. The exact behavior can vary by phone and software version, but on a current iPhone or Android phone you can usually still see your position on a map with airplane mode on.

There are catches. Without a data connection, the map itself may not load unless you downloaded it beforehand. The first fix can also take longer, because phones normally use mobile data or Wi-Fi to speed GPS up. This is called assisted GPS.

This matters for privacy and investigations. Airplane mode stops the phone talking to towers, but apps can still record GPS positions on the phone and upload them once a connection comes back. Turning off location is a separate setting.