ETA是預計到達的時間 (Estimated Time of Arrival) ETD是預計出發時間 (Estimated Time of Departure) 舉例幾個例子就很容易明白了，以下的用法都可以： 下一班高鐵將在13:45進站。 ← ETA 13:45 本次列車將於13:50自本站發車。 ← ETD 13:50 本次列車將於16:30到達終點站高雄。 ← ETA 16:30 正在下載1個檔案，估計完成時間5分鐘。 ← ETA 5 minutes。 以下取自wikipedia做一點很簡便的翻譯： The estimated time of arrival or ETA is a measure of when a vehicle, aircraft, cargo, emergency service or computer file is expected to arrive at a certain place. 估計到達的時間 是用來估計交通工具、貨物、救護隊、或電腦檔案到達某地的時間(對電腦檔案來說是估計下載完成時間)。 One of the more common uses 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. 在大眾交通工具上特別常用，也就是照時刻表、或依據交通流量來做估計。 In this respect, the phrase or its abbreviation is often paired with its complement, " estimated time of departure " or " ETD ", to indicate the expected start time of a particular journey.
