The estimated time of arrival (ETA) is the time when a ship, vehicle, aircraft, cargo, person, or emergency service is expected to arrive at a certain place.
[1][2][3] One of the more common uses of the phrase is in public transportation where the movements of trains, buses, airplanes and the like can be used to generate estimated times of arrival depending on either a static timetable or through measurements on traffic intensity.
For example, a certain flight may have a calculated ETA based on the speed by which it has covered the distance traveled so far.
The remaining distance is divided by the speed previously measured to roughly estimate the arrival time.
[citation needed] This particular method does not take into account any unexpected events (such as new wind directions) which may occur on the way to the flight's destination.