STD, ETD, ATD: Reading an Airport Departure Board

A departure board packs a lot into one line: a flight number, a destination, a time, and a short code next to that time that most travellers have never had explained. If you have ever typed something close to "std atd meaning flight board" into a search bar while staring up at one, the short version is that none of it is random. Each code answers a different question about the same flight, and the board switches between them as the flight moves closer to leaving. This covers what each code means at Delhi, Mumbai and Bengaluru alike, how the arrivals side mirrors it, and what the status word next to the time is telling you.

STD: the time nobody re-checks

STD stands for Scheduled Time of Departure, the date and time a flight was originally planned to leave the stand. SKYbrary defines it as the "date and time when a flight is scheduled to depart from the departure stand" (SKYbrary, Scheduled Time of Departure (STD), captured 2026-09-23). SKYbrary's own note is worth sitting with: STD is "normally not used in an operational environment" and is "mostly of interest to passengers". Airlines, air traffic control and ground handlers plan around updated times, not the original schedule. The board keeps STD visible anyway, because it is the number on your ticket and the baseline everything else gets compared against.

ETD: the number that moves

ETD, Estimated Time of Departure, is the airline's current best guess at when the aircraft will push back or taxi out. In IATA's movement-message format, the estimated departure event maps to EOBT, Estimated Off-Block Time, a field airlines and airports exchange to keep each other's systems in sync (Avinor xwiki, MVT - Movement Message, captured 2026-09-23). When ETD appears next to a flight, the original STD no longer holds and the airline has issued a revised estimate, whether that is five minutes later because of a runway queue or three hours later because of an earlier delay working through the aircraft's day.

ATD: what actually happened

ATD, Actual Time of Departure, is the recorded fact rather than a plan or an estimate. In the same movement-message format, the actual off-block event is logged as AOBT, Actual Off-Block Time: the moment the aircraft physically starts moving away from the gate, chocks out (Avinor xwiki, MVT - Movement Message, captured 2026-09-23). Once ATD is on the board, the flight has left the stand. It has not necessarily taken off yet, since taxiing and a runway queue still sit between off-block and wheels-up, but the uncertainty that ETD carried is gone for that leg of the journey.

The arrivals mirror: STA, ETA, ATA

Arrivals boards run the same three-stage logic in reverse. STA is the Scheduled Time of Arrival on the original timetable. ETA is the current estimate, and it updates as a flight's actual progress becomes known mid-route. ATA is the recorded actual arrival, and the movement-message format again splits it into two real events: ALDT, Actual Landing Time, when the wheels touch down, and AIBT, Actual In-Block Time, when the aircraft reaches the gate and the parking brake goes on (Avinor xwiki, MVT - Movement Message, captured 2026-09-23). For someone waiting in an arrivals hall, that gap between landing and reaching the gate is exactly the stretch where a board marked "Landed" still means a wait before anyone walks out.

The status word is doing more work than the code

The letters cover time. A flight information display board also carries a plain-language status alongside them, such as "Boarding", "Gate Closed", "Delayed" or "Landed", and that word is what most travellers actually scan for. A flight information display system's job, per its own definition, is to show the flight number, origin or destination, "the expected arrival or departure time and/or the updated time (reflecting any delays)", and "the status of the flight", with departing flights also carrying the check-in counter and gate number (Wikipedia, Flight information display system, captured 2026-09-23). "Delayed" on its own does not tell you how late; that detail sits in whichever ETD or ETA figure is currently displayed next to it, which is why the two need reading together rather than one instead of the other.

Reading a line, start to finish

Put together, a single board entry tells a short story in order: the STD sets the plan, an ETD appears and updates as that plan slips or holds, a status word narrates where the flight is in its ground process, and an ATD closes the entry out once the aircraft has actually left the stand. The same sequence, in reverse, runs on the arrivals side from STA through ETA to ATA. None of the six letters change what a flight is doing; they just say which stage of certainty the airport is reporting for it at that moment.

Where TrackMyWings stands today

TrackMyWings™ is a private beta on Android, shipped 2026-08-24 on the Play internal testing track. Public launch has no fixed date. A planned flight passport and gate and status alerts, not yet shipped, are built around exactly this kind of board detail: the aim is to turn scheduled, estimated and actual times into one clear picture for the person waiting, rather than three letters to decode. The line the product is built against is "Every flight you take. Every person waiting."

FAQ

What is the difference between ETD and ATD? ETD is an estimate that can still change; ATD is the recorded fact once the aircraft has actually left the stand. A board showing ETD is telling you a current best guess, while ATD means that event has already happened.

Why does a board show STD if it is not accurate anymore? STD is the original scheduled time and stays on the board as the reference point, even though SKYbrary's own definition notes it is mostly of interest to passengers rather than something operations teams work from once a flight is running late.

Does "Landed" mean the flight has reached the gate? Not necessarily. The movement-message format records landing (ALDT) and reaching the gate (AIBT) as two separate actual events, so a board marked "Landed" can still be some minutes ahead of arriving passengers walking out.

Are STD, ETD and ATD used the same way for arrivals? The letters change to STA, ETA and ATA, but the logic is identical: a schedule, a current estimate, and a recorded actual event, in that order.

Sources

• SKYbrary Aviation Safety, Scheduled Time of Departure (STD), https://skybrary.aero/articles/scheduled-time-departure-std (captured 2026-09-23). Supports the STD definition and its passenger-facing, non-operational status.
• Avinor xwiki (ADD/MIFT), MVT - Movement Message, https://xwiki.avinor.no/display/ADDMIFTM/MVT+-+Movement+Message (captured 2026-09-23). Supports the ATD/AOBT, ETD/EOBT, ATA/ALDT+AIBT and ETA/ELDT+EIBT field definitions.
• Wikipedia, Flight information display system, https://en.wikipedia.org/wiki/Flight_information_display_system (captured 2026-09-23). Supports what a departure/arrival board displays, including status words and departure-only fields.