It might come as a surprise but not everywhere has an outlet to charge your devices.  There are still many planes that do not have outlets or USB ports.  You need to make sure that your phone has power when you land so you can call the hotel, your ride, or look up important information.  This battery bank also has the added benefit of a solar panel.  While it won’t charge fast, it will give you enough juice if your phone and battery bank are dead in an emergency.