What Is STD? Definition & Meaning in Aviation
STD (scheduled time of departure) is the departure time published in the airline’s timetable.
In plain language
Airlines measure punctuality against it, usually counting a flight as on time if it leaves or arrives within a set number of minutes of schedule.
Example
A boarding pass showing 09:30 departure is showing the STD.
Why it matters
The STD is the time on your ticket and the reference for check-in and boarding cut-offs. Airlines count a flight as on time or late by comparing the actual departure with it.