What does the NOTAM duration 'Until Cancelled' mean for flight operations?

What does the NOTAM duration 'Until Cancelled' mean for flight operations?

• A. It expires after 24 hours
• B. It is valid only during daylight
• C. It remains in effect until explicitly canceled
• D. It is canceled automatically after a fixed date

Answer: (C)

In NOTAMs, a duration of “Until Cancelled” means there is no fixed end date or time. The NOTAM stays in effect until someone explicitly cancels it, typically by issuing a cancellation NOTAM or a new NOTAM that supersedes it. This makes the NOTAM live for as long as the condition it describes persists, and it requires ongoing monitoring to catch when it is finally cancelled. That’s why this is the best answer: the other options imply a time limit or automatic expiration that does not apply to a NOTAM labeled as “Until Cancelled.” It does not expire after 24 hours, it isn’t tied to daylight or any other daily cycle, and it isn’t canceled automatically after a fixed date.

In NOTAMs, a duration of “Until Cancelled” means there is no fixed end date or time. The NOTAM stays in effect until someone explicitly cancels it, typically by issuing a cancellation NOTAM or a new NOTAM that supersedes it. This makes the NOTAM live for as long as the condition it describes persists, and it requires ongoing monitoring to catch when it is finally cancelled.

That’s why this is the best answer: the other options imply a time limit or automatic expiration that does not apply to a NOTAM labeled as “Until Cancelled.” It does not expire after 24 hours, it isn’t tied to daylight or any other daily cycle, and it isn’t canceled automatically after a fixed date.