G-meters

Also called accelerometers, indicate the instant acceleration the aircraft is supporting. Taking acceleration of gravity (which is 9.8 m/s2) as a reference, and designated with the letter 'G ' in the International Metric System.
Therefore when we are only subjected to the acceleration of gravity (standing on the ground or flying straight and even) the instrument reads G = 1. When starting to climb the instrument reads G> 1 and when starting to descend the instrument reads G