You have a music enabled mobile phone & you are on a long train/bus journey. You love to hear music on the go. But you rather, power-off the phone & slip it in your bag.
You do this because, you know that the battery will drain & you’ll end up with no connectivity, once you reach the destination.
[Airplane mode] in your mobile can come to rescue. This mode turns off all the radio-communications & keeps the other phones features such as mediaplayer, camera, memos, etc active. Enabling the Airplane mode will make your phone radio-silent & makes it to save significant battery power by not constantly tracking the cell towers that come in your way. So an Airplane mode helps even your train/bus journey.
Don’t want people to disturb you? Don’t switch off your phone. Airplane mode is handy. When you don’t want to disturb others, kick in the Silent mode.
Ok. Now enjoy a few extra hours of music & dream about flying in air.
Update #0: Airplane Mode is available in most of the mobile phones. For instance, my[Motorola E398] has it in MainMenu > Settings > AirplaneMode