Final answer:
The Third Class Medical Certificate Privileges for a pilot under 40 last 60 calendar months. It's crucial for pilots to maintain a valid certificate to comply with FAA regulations and ensure safety.
Step-by-step explanation:
The duration of Third Class Medical Certificate Privileges for a pilot who is under 40 years old is 60 calendar months (5 years). The Federal Aviation Administration (FAA) specifies this duration to ensure that pilots meet the medical fitness requirements needed for the safe operation of an aircraft. It is important for the pilot to keep track of the expiration date, as flying with an expired medical certificate can have legal and safety implications.