It’s like having a tour guide telling you about the places you are flying over. The app has a database of flight routes in the continental United States. After entering your departure and arrival points, you choose the flight path and tell the when you are taking off. From that moment, the app will tell you the estimated arrival time, as well as showing your plane in its built-in map and give you information about the points of interest near you.
As you can imagine, it’s not exactly accurate. The creator of WindowSeat says that “one of the app’s core features is the dialogue between it and the user. In this way, a user can make the flight prediction even more accurate by using their own observations as well as information they gather from the cabin staff.”
It seems to me like a flaw-turned-into-a-feature that could be solved with GPS support. After all, GPS support is active on the iPhone even with Flight Mode on.
Still, it sounds like a nice pastime to those people who like flying and maps.