Definition
A specified interval between two points in time, used in aviation regulations and maintenance documents to define how long an action, condition, or authorization remains in effect.
Plain English
A set length of time with a clear start and end, such as 30 days, 100 flight hours, or until a specific date.
Context Anchor
Seen in regulations, operating instructions, maintenance requirements, and pilot currency rules when something must be done within a certain time window.
Why Pilots Care
Many privileges, inspections, and authorizations are valid only for a defined period of time. Knowing exactly when that period starts and ends is what keeps a pilot or aircraft legal.
Intuition Check
Do not treat period of time as a loose phrase meaning “for a while.” In aviation use, it usually points to a specific time window that must be counted correctly.
Example Sentence 1
The medical certificate is valid for a period of time defined by the holder's age and class of certificate.
Example Sentence 2
All training records must be kept for a period of time of at least two years after the pilot's last flight.