The altimeter is a diagram that expands and retracts as the ambient air pressure changes. It compares the pressure difference of the currently measured air pressure to a reference pressure set with an adjustment knob. The altimeter doesn't show the altitude above sea level or above ground correct...
This article focuses on taking you through all of the basics for the six instruments in a Cessna 172, one of the most common aircraft. The Cessna 172 is illustrative of all similar types of aircraft. Moreover, if needed, you will be able...