Besides subscription-based flight tracking system, there are also free and open-source flight tracking system users can download that allows users to keep track of flights in real-time. The online flight tracking system lets users search for a specific flight, destination, or airline. It also lets users create filters for users? searches. Users can view flight information and even bookmark specific airports in the flight tracking system. In addition to these, users can even view live flight routes around the world. These apps make tracking planes an incredibly convenient process. There are even features that allow users to send alerts to a specific email address when an aircraft changes course. Then, users can quickly access information that's pertinent to users' travels.