TodayFlights is a Notification Center widget that allows you to monitor flights as they depart, fly and land. It uses the system flight tracking framework included in macOS.
- Download the DMG file from above and copy the TodayFlights app to the Applications folder
- Run the TodayFlights app
- Open Notification Center, and click "1 new" at the bottom of the panel
- Add the TodayFlights widget
Customise the flight being tracked by hovering over the widget and clicking the info button that appears in the top-right corner.