Definition
A departure time issued to a pilot by ATC, individually or through an authorized relay, after which the pilot may proceed under the conditions of the IFR clearance.
Plain English
The earliest time air traffic control will let you take off on your IFR flight. You wait until that time, then you can go.
Context Anchor
Seen in ICAO-based ATC procedures and international operations where an aircraft is waiting for further clearance or has to know what to do if radio contact is lost.
Derivation
From 'release,' meaning to let go or set free. The release time is the moment ATC frees the aircraft to begin its flight under IFR.
Why Pilots Care
Maintains safe spacing between aircraft; missing the time can cause departure delays or conflicts.
Grounding Statement
Think of it as: “Do not continue before this time unless ATC gives you permission sooner.”
Intuition Check
Release time does not simply mean the time you are free to do anything. In this ICAO use, it is tied to ATC clearance and, if radios fail, it tells you the earliest time you should continue.
Example Sentence 1
Center issued a release time of 1430Z, so the pilot held short of the runway until two minutes before that time before announcing departure.
Example Sentence 2
The pilot asked for an earlier release time because weather at the destination was improving.