Final answer:
The requirement to have an aircraft's altimeter certified is addressed in FAR Part 91, which deals with general operating and flight rules for aircraft.
Step-by-step explanation:
The requirement to have an aircraft's altimeter certified can be found in FAR Part 91. FAR stands for Federal Aviation Regulations and Part 91 specifically addresses general operating and flight rules for aircraft. In Section 91.411, it states that the altimeter must be tested and inspected within certain intervals by an approved facility and the aircraft must have an appropriate maintenance record.