Definition
A required check of the static pressure system, altimeter, and automatic altitude reporting equipment, performed by an appropriately certified person, that must be completed within the preceding 24 calendar months for the aircraft to be operated under instrument flight rules in controlled airspace. The inspection verifies the system holds pressure correctly, the altimeter reads accurately within tolerances, and the encoding altimeter reports the correct altitude to air traffic control.
Plain English
A test done at least every two years to make sure the aircraft's altitude-measuring equipment is leak-free and reading correctly, including the part that automatically sends the altitude to controllers.
Context Anchor
Pilots encounter this in aircraft maintenance records before instrument flight, especially when checking whether the aircraft is legal to fly in controlled airspace using instruments.
Derivation
“Altimeter” combines “altitude,” meaning height, with “meter,” meaning a measuring device. “Inspection” comes from a word meaning to look into or examine. Together, the phrase means an official examination of the equipment that measures the aircraft’s height.
Why Pilots Care
Accurate altitude information prevents controlled flight into terrain and satisfies regulatory requirements for legal IFR flight.
Intuition Check
Do not read “inspection” here as a quick pilot look at the instrument before takeoff. In this context, it means a required maintenance test and record entry, normally due every 24 calendar months for instrument flight in controlled airspace.
Example Sentence 1
Before filing IFR, the pilot checked the logbook to confirm the altimeter system inspection was within the last 24 calendar months.
Example Sentence 2
Before the checkride, the owner scheduled the altimeter system inspection to keep the aircraft legal for instrument approaches.