Definition
An ATC phrase used to inform a pilot that a delay of unknown length is being applied to their flight, with a reason given if available, and a specific time at which the pilot can expect to receive a further clearance. It is issued when ATC cannot determine how long the delay will last but wants the pilot to plan around a known check-in or update time.
Plain English
ATC is telling you: 'You're going to be held up. We don't know for how long. Here's why, if we know. Check back with us at this time and we'll have more information for you.'
Context Anchor
Heard in radio communications when a flight is being held, kept on the ground, or otherwise delayed by air traffic control.
Derivation
“Indefinite” comes from Latin roots meaning “not fixed” or “not limited.” That helps here because the delay has no known ending yet. In aviation, “clearance” means an authorization or instruction from air traffic control, not simply being free of something.
Why Pilots Care
Gives the pilot a concrete time to expect the next instruction so fuel planning and situational awareness can be maintained without immediate pressure to depart the hold or request a new clearance.
Intuition Check
Do not read “delay indefinite” as “wait forever” or “you have been forgotten.” It means the controller cannot yet give a definite delay length. Also, the Expect Further Clearance time is not automatic permission to proceed; it is the time to expect the next clearance or instruction.
Example Sentence 1
Center advised, 'November Three Two Alpha, delay indefinite due to traffic volume, expect further clearance at one seven three zero Zulu.'
Example Sentence 2
After the ground controller said 'Delay indefinite, reason if known, expect further clearance at 45 past the hour,' the pilot updated the fuel log and briefed the crew on the expected timeline.