Definition 1 of 2
Definition
The time a pilot expects an aircraft to arrive over a specified fix or to land at the destination airport, based on current groundspeed, distance remaining, and known winds. ETA is expressed in coordinated universal time (UTC) for IFR flight plans and ATC use, and is updated in flight as conditions change.
Plain English
The clock time you expect to reach where you are going. It is a forecast, not a promise, and it gets revised as the flight progresses.
Context Anchor
Seen in flight planning, navigation logs, flight plans, and radio communication with air traffic control.
Derivation
From Latin aestimatus, 'to value or judge.' An ETA is a judged or calculated arrival time -- a best estimate based on the numbers you have right now, not a guaranteed result.
Why Pilots Care
Coordinates arrivals with ATC, supports fuel and reserve planning, and prevents sequencing conflicts.
Intuition Check
Estimated does not mean guaranteed or scheduled. It means the best current prediction, which may change if speed, wind, routing, or delays change.
Example Sentence 1
The pilot reported an ETA of 1845 UTC at the destination after recalculating for stronger-than-forecast headwinds.
Example Sentence 2
ATC requested the aircraft's estimated time of arrival at the next waypoint for sequencing.