First, RF emissions from phones really don't affect airplane equipment. They haven't for a long time, if they ever have. Airplane mode is one of those things t

First, RF emissions from phones really don't affect airplane equipment. They haven't for a long time, if they ever have. Airplane mode is one of those things that sticks around because people think it's important and they expect it. It doesn't really help airplanes, it's more of a general "disable radios" mode now. Typically airplane mode does turn off all radios in your device, but modern devices allow you to turn WiFi or Bluetooth back on while keeping the cell radio turned off. I think the reasoning here is that while in a plane, your phone will try really hard to find a cell tower to connect to. The output power of the radio will get turned up to max, which ends up being a lot more RF power being sent out than your WiFi or Bluetooth radio puts out. Hypothetically this can interfere with safety-critical electronics in the plane, but in reality those systems are incredibly robust and very well shielded.