Definition
An ATC phrase used when a hold or delay cannot be assigned a specific length. ATC tells the pilot to expect an indefinite delay, gives the reason if it is known, and provides an Expect Further Clearance (EFC) time at which further instructions or a release can be anticipated.
Plain English
Controllers are saying: we don't know how long you'll be held up, here's why if we know, and here's the time to expect us to talk to you again with a new clearance.
Context Anchor
Heard on the radio when air traffic control cannot immediately let an aircraft continue as planned, such as during traffic, weather, runway, or route delays.
Derivation
Delay means to put something off until later. Indefinite means not fixed or not clearly known. Clearance means an official approval or instruction to proceed. Together, the phrase means the wait is not yet fixed, but a later time is being given for the next expected instruction.
Why Pilots Care
Enables accurate fuel planning and workload management when the length of a hold cannot yet be predicted.
Grounding Statement
The key point is that the delay is open-ended, but the pilot is still given a time to expect the next clearance or update.
Intuition Check
Do not read “expect further clearance” as permission to continue at that time. It only means that another clearance or update is expected then; the pilot must wait for the actual instruction.
Example Sentence 1
Center advised, 'Cessna 24X, hold as published, delay indefinite due to traffic volume, expect further clearance at 1545 Zulu.'
Example Sentence 2
The pilot responded to the indefinite delay instruction by reporting a known mechanical reason.