Plain English Meaning
A set length of time with a clear start and end, such as 30 days, 100 flight hours, or until a specific date.
Full 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.
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.