Definition
A regulatory time period measured as 24 full calendar months, ending on the last day of the 24th month after the event being timed. The count is not based on the exact day-to-day date but on the month itself, so any portion of the starting month is disregarded for counting purposes.
Plain English
A two-year deadline that runs to the end of the month, not to the exact same date two years later. If something was done in March, it stays valid through the end of March two years from then.
Context Anchor
Seen in pilot currency and continuing education requirements, especially when checking whether a flight review or similar requirement is still current.
Derivation
Calendar month' refers to a named month on the calendar (January, February, etc.) rather than a 30-day period. Pairing it with '24' means counting whole named months, which is why the deadline always lands on the last day of a month.
Why Pilots Care
It fixes the precise expiration date for regulatory currency items, so pilots know exactly when an action such as a flight review must be repeated.
Intuition Check
Do not read 24 calendar months as exactly 24 months to the same day, or as a fixed number of days. In FAA use, calendar-month timing usually runs to the end of the applicable month.
Example Sentence 1
A flight review completed on March 12, 2025 remains valid through March 31, 2027 -- the end of the 24th calendar month.
Example Sentence 2
For a pilot under age 40, the third-class medical certificate is valid for 24 calendar months from the date of the examination.