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. In this respect, the phrase or its abbreviation is often paired with its complement, estimated time of departure (ETD), to indicate the expected start time of a particular journey. This information is often conveyed to a passenger information system as part of the core functionality of intelligent transportation systems.
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. 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.
ETA is also used metaphorically in situations where nothing actually moves physically, as in describing the time estimated for a certain task to complete (e.g. work undertaken by an individual; a computation undertaken by a computer program; or a process undertaken by an organization). The associated term is "estimated time of accomplishment", which may be a backronym.
Accurate and timely estimations of times of arrival are important in several application areas:
- In air traffic control arrival sequencing and scheduling, where scheduling aircraft arrival according to the first-come-first-served order of ETA at the runway minimizes delays.
- In airport gate assignment methods, to optimize gate utilization.
- In elevator control, to minimize the average waiting time or journey time of passengers (destination dispatch).
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- Propp, Douglas A.; Rosenberg, Craig A. (July 1991). "A comparison of prehospital expected time of arrival and actual time of arrival to an emergency department". The American Journal of Emergency Medicine. 9 (4): 301–303. doi:10.1016/0735-6757(91)90045-L. PMID 2053997.
- Carr, Gregory C.; Erzberger, Heinz; Neuman, Frank (June 2000). "Fast-time study of airline-influenced arrival sequencing and scheduling". Journal of Guidance, Control, and Dynamics. 23 (3): 526–531. Bibcode:2000JGCD...23..526C. doi:10.2514/2.4559.
- Roy, Kaushik; Levy, Benjamin; Tomlin, Claire J. (August 2006). "Target tracking and Estimated Time of Arrival (ETA) Prediction for Arrival Aircraft". AIAA Guidance, Navigation, and Control 2006. AIAA. AIAA2006-6324.
- Lim, A.; Rodrigues, B.; Zhu, Y. (2005). "Airport Gate Scheduling with Time Windows". Artificial Intelligence Review. 24 (1): 5–31. doi:10.1007/s10462-004-7190-4. S2CID 19496597.
- Xiong, Bo; Luh, Peter B.; Chang, Shi Chung (April 2005). "Group Elevator Scheduling with Advanced Traffic Information for Normal Operations and Coordinated Emergency Evacuation". Robotics and Automation (ICRA 2005). IEEE. pp. 1419–1424.
- Rong, Aiying; Hakonen, Henri; Lahdelma, Risto (December 2003). Estimated Time of Arrival (ETA) Based Elevator Group Control Algorithm with More Accurate Estimation. Turku Centre for Computer Scienceo. ISBN 952-12-1289-6. Retrieved July 11, 2012.