PrayInTheSky
Live on the web
Type in a flight number and a date. PrayInTheSky works out when each prayer falls during the flight, using the plane's route, and shows where you will be at each time. On board you can refine the times from your phone's GPS, and you can switch the Asr time between the Hanafi and standard methods. It runs in the browser with no sign-up. Add it to your home screen and it works with no connection.
Open prayinthesky.com