Scheduled, Estimated and Actual Flight Times, Explained

Scheduled vs estimated vs actual time is the whole reason a flight app and the airport board can show two different numbers for the same flight at the same minute, and neither one is wrong. A flight carries three separate clocks, not one. The scheduled time is the plan an airline filed weeks or months ago. The estimated time is that plan updated with whatever the airline knows right now. The actual time is what genuinely happened, recorded the moment it happens. Most of the confusion at a gate or on a pickup drive comes from reading one of these three as if it were another. This piece walks through what each clock means, where you see it, and which one is worth trusting depending on where you are in the journey.

Scheduled time: the plan filed in advance

The scheduled time of departure and arrival, often written STD and STA, is the date and time a flight is scheduled to depart or arrive, as published in the airline's own timetable (SKYbrary Aviation Safety, "Scheduled Time of Departure (STD)," captured 2026-09-23). Airlines typically build that timetable months ahead of the day itself, as part of routine schedule and slot planning, long before anyone knows which specific aircraft, crew or weather will actually show up. This is the number on your original booking confirmation and the number a route search returns by default. It is a planning figure, not a promise about today's specific aircraft. Airlines build schedules around block time: how long a route is expected to take end to end, given typical winds, typical taxi times, and the turnaround the aircraft needs between flights. None of that accounts for today's actual weather, today's actual air traffic, or today's actual ground delay at the airport the aircraft is coming from.

Because the scheduled time is fixed at booking and rarely changes after that, it is the most stable of the three clocks and the least useful one on the day of travel itself. If you are planning a trip weeks out, the scheduled time is exactly what you should be looking at. If you are already at the airport, it has already done its job and handed off to the next clock.

Estimated time: the airline's current best guess

The estimated time of departure or arrival, ETD or ETA, is the airline's updated prediction for when the flight will actually leave or land, given everything known at the moment the estimate is issued (AltexSoft, "Estimated Time of Departure or Delivery (ETD)," captured 2026-09-23). This is the number that moves, and it is the number behind an airline's own published on-time figures, which are built by comparing estimated and actual times against the schedule over many flights rather than one. An inbound aircraft running late, a longer-than-usual queue for de-icing, a ground stop at the destination: all of these push the estimated time away from the scheduled one, sometimes by minutes and sometimes by hours. A flight can carry an estimated time that is earlier than scheduled too, when conditions run better than the original plan assumed, though airlines tend to be conservative about publishing an early estimate.

The estimate is not a guarantee. It is the airline's operations team updating a prediction as new information arrives, and it can change again before the flight actually moves. This is the clock worth watching once you are within a few hours of departure, because it is the closest thing to a live read on what is actually going to happen, without yet being the confirmed fact of it.

Actual time: what genuinely happened

The actual time of departure or arrival, ATD or ATA, is recorded the moment the event itself occurs: wheels off the ground, or wheels on the ground and the aircraft at the gate. There is no more prediction involved once this number appears. Estimated and actual times are tracked as separate, distinct fields (OAG Knowledge Base, "Understanding Flight Status States," captured 2026-09-23), and once an actual time exists, that is the number a status board or a tracking app will show for that leg of the journey, ahead of the estimate that came before it.

A useful way to think about the three clocks together: scheduled is the plan, estimated is the forecast, and actual is the record. Only one of the three is ever final, and it is the last one to appear. Everything before that is a prediction of varying confidence, and treating a prediction as a fact is where most airport confusion starts.

Why the app and the board can disagree

If a flight app and an airport display board show different times for the same flight, the two most common reasons are timing and source, not error. Status data does not update everywhere simultaneously. One system can be refreshing on its own cycle while another has not yet pulled the newest estimate, so for a short window the two genuinely disagree without either being wrong; they are simply looking at different moments of the same feed. The second reason is which clock each display defaults to: one board might default to showing the scheduled time until an update arrives, while an app defaults to the most recent estimate it has, and the two labels can look confusingly similar without being the same field.

There is a third, quieter source of disagreement worth knowing about if you are using a live map rather than a status board: most consumer flight trackers, including the community networks several of them are built on, rely on ADS-B, where an aircraft broadcasts its own position and ground-based receivers pick that broadcast up (Wikipedia, "Automatic Dependent Surveillance-Broadcast," captured 2026-09-23). Coverage from that kind of network is generally strong near a dense cluster of receivers on land, and it thins out or disappears far from land, over open ocean, simply because there is no receiver out there to hear the signal. That is a property of how the technology works, not a fault in any particular app, and it explains why a live map can go quiet on a leg of a flight while the airline's own status feed, which does not depend on ADS-B receivers at all, keeps reporting a clean estimate or actual time.

Which clock to trust, and when

The short version: trust the scheduled time when you are planning ahead, trust the estimated time when you are within a few hours and want the airline's current read, and trust the actual time as final only once it has actually posted. If you are booking connecting flights or building a pickup plan around someone's arrival, work backward from the scheduled time until roughly two hours before departure, then switch your attention to the estimated time and keep an eye on it as the window closes. Once wheels are down, the actual time is the only number left that matters, and it is the one that will not change again.

One habit worth building: if a source shows only one time with no label at all, treat it as the least useful, least current version until you can confirm which of the three clocks it actually is. A label-free "departure time" three days out is almost certainly the scheduled time, and a label-free one an hour before departure is almost certainly an estimate. The label is doing real work, and skipping it is how a scheduled time gets mistaken for a live status update.

How TrackMyWings helps

TrackMyWings™ is a live flight-tracking platform in development, built around the idea that reading a flight's status should not require knowing which of three clocks you are looking at. A private beta shipped on 2026-08-24, Android only, on the Play internal testing track with a small group of named testers. Public launch has no fixed date; it depends on trade-mark clearance and on the app being good enough to earn the download. Planned features, including gate and status alerts that surface the estimated and actual clocks as they update, are in development and not yet shipped. Nothing here is a claim about what the app tracks today; it is a statement of what exists and what does not, so you know exactly what you would be trying before you go looking for it. See our live flight tracking feature page for how that view is built, the rest of our flight-tracking coverage for related explainers, and an airline page such as Lufthansa in the directory.

Questions people ask

What do STD and STA stand for? Scheduled Time of Departure and Scheduled Time of Arrival: the times an airline published when it built the timetable, not a current read on today's flight.

What is the difference between ETA and ATA? ETA is the airline's current prediction of arrival time, updated as new information comes in. ATA is the recorded, confirmed arrival time once the aircraft is actually on the ground. Once ATA exists, boards and apps show it in place of the earlier estimate.

Why does my app show a different time than the airport board? Usually a timing gap between two systems refreshing on different cycles, or a difference in which clock each display defaults to showing. Neither is necessarily wrong; check whether each is labelled scheduled, estimated or actual before assuming an error.

Which time should I use to plan when to leave for the airport? The scheduled time until you are within a couple of hours of departure, then the estimated time, which reflects what the airline currently expects rather than what it originally planned.

Does the estimated time ever get earlier than the scheduled time? Yes, when conditions run better than the original plan assumed, though airlines tend to be conservative before publishing an early estimate.

Sources

• SKYbrary Aviation Safety, "Scheduled Time of Departure (STD)," https://skybrary.aero/articles/scheduled-time-departure-std, captured 2026-09-23
• AltexSoft, "Estimated Time of Departure or Delivery (ETD)," https://www.altexsoft.com/glossary/estimated-time-of-departure-or-delivery-etd/, captured 2026-09-23
• OAG Knowledge Base, "Understanding Flight Status States," https://knowledge.oag.com/docs/understanding-flight-status-states, captured 2026-09-23
• Wikipedia, "Automatic Dependent Surveillance-Broadcast," https://en.wikipedia.org/wiki/Automatic_dependent_surveillance–broadcast, captured 2026-09-23